1 /* SPDX-License-Identifier: MIT */
3 /* this is a pretty robust parser for EDID, and we're tasked with parsing
4 * an arbitrary panel. We will pass it a raw EDID block and a struct which
5 * it must fill in with values. The set of values we need is pretty limited
10 #include <commonlib/helpers.h>
12 #include <console/console.h>
20 int claims_one_point_oh
;
21 int claims_one_point_two
;
22 int claims_one_point_three
;
23 int claims_one_point_four
;
24 int nonconformant_digital_display
;
25 int nonconformant_extension
;
26 int did_detailed_timing
;
27 int has_name_descriptor
;
28 int has_range_descriptor
;
29 int has_preferred_timing
;
30 int has_valid_checksum
;
32 int has_valid_dummy_block
;
35 int has_valid_detailed_blocks
;
36 int has_valid_extension_count
;
37 int has_valid_descriptor_ordering
;
38 int has_valid_descriptor_pad
;
39 int has_valid_range_descriptor
;
40 int has_valid_max_dotclock
;
41 int has_valid_string_termination
;
42 int manufacturer_name_well_formed
;
43 int seen_non_detailed_descriptor
;
44 int warning_excessive_dotclock_correction
;
45 int warning_zero_preferred_refresh
;
46 enum edid_status conformant
;
49 /* Stuff that isn't used anywhere but is nice to pretty-print while
50 we're decoding everything else. */
56 unsigned int version
[2];
57 unsigned int nonconformant
;
66 const char *syncmethod
;
67 const char *range_class
;
71 static struct edid tmp_edid
;
73 static int manufacturer_name(unsigned char *x
, char *output
)
75 output
[0] = ((x
[0] & 0x7C) >> 2) + '@';
76 output
[1] = ((x
[0] & 0x03) << 3) + ((x
[1] & 0xE0) >> 5) + '@';
77 output
[2] = (x
[1] & 0x1F) + '@';
80 if (isupper(output
[0]) &&
90 detailed_cvt_descriptor(unsigned char *x
, int first
)
92 const unsigned char empty
[3] = { 0, 0, 0 };
93 static const char *names
[] = { "50", "60", "75", "85" };
94 int width
= 0, height
= 0;
96 int fifty
= 0, sixty
= 0, seventyfive
= 0, eightyfive
= 0, reduced
= 0;
98 if (!first
&& !memcmp(x
, empty
, 3))
102 height
|= (x
[1] & 0xf0) << 4;
106 switch (x
[1] & 0x0c) {
108 width
= (height
* 4) / 3; break;
110 width
= (height
* 16) / 9; break;
112 width
= (height
* 16) / 10; break;
114 width
= (height
* 15) / 9; break;
124 fifty
= (x
[2] & 0x10);
125 sixty
= (x
[2] & 0x08);
126 seventyfive
= (x
[2] & 0x04);
127 eightyfive
= (x
[2] & 0x02);
128 reduced
= (x
[2] & 0x01);
131 printk(BIOS_SPEW
, " (broken)\n");
134 " %dx%d @ (%s%s%s%s%s) Hz (%s%s preferred)\n",
138 seventyfive
? "75 " : "",
139 eightyfive
? "85 " : "",
140 reduced
? "60RB " : "",
141 names
[(x
[2] & 0x60) >> 5],
142 (((x
[2] & 0x60) == 0x20) && reduced
) ? "RB" : "");
148 /* extract a CP437 string from a detailed subblock, checking for termination (if
149 * less than len of bytes) with LF and padded with SP.
152 extract_string(unsigned char *x
, int *valid_termination
, int len
)
154 static char ret
[EDID_ASCII_STRING_LENGTH
+ 1];
155 int i
, seen_newline
= 0;
157 memset(ret
, 0, sizeof(ret
));
159 for (i
= 0; i
< MIN(len
, EDID_ASCII_STRING_LENGTH
); i
++) {
162 *valid_termination
= 0;
165 } else if (x
[i
] == 0x0a) {
168 /* normal characters */
176 /* 1 means valid data */
178 detailed_block(struct edid
*result_edid
, unsigned char *x
, int in_extension
,
179 struct edid_context
*c
)
181 struct edid
*out
= &tmp_edid
;
184 if (console_log_level(BIOS_SPEW
)) {
185 printk(BIOS_SPEW
, "Hex of detail: ");
186 for (i
= 0; i
< 18; i
++)
187 printk(BIOS_SPEW
, "%02x", x
[i
]);
188 printk(BIOS_SPEW
, "\n");
191 /* Result might already have some valid fields like mode_is_supported */
194 if (x
[0] == 0 && x
[1] == 0) {
195 /* Monitor descriptor block, not detailed timing descriptor. */
199 "Monitor descriptor block has byte 2 nonzero (0x%02x)\n",
201 c
->has_valid_descriptor_pad
= 0;
203 if (x
[3] != 0xfd && x
[4] != 0x00) {
206 "Monitor descriptor block has byte 4 nonzero (0x%02x)\n",
208 c
->has_valid_descriptor_pad
= 0;
211 c
->seen_non_detailed_descriptor
= 1;
214 * in principle we can decode these, if we know what
216 * 0x0f seems to be common in laptop panels.
217 * 0x0e is used by EPI: http://www.epi-standard.org/
220 "Manufacturer-specified data, tag %d\n", x
[3]);
225 printk(BIOS_SPEW
, "Dummy block\n");
226 for (i
= 5; i
< 18; i
++)
228 c
->has_valid_dummy_block
= 0;
232 printk(BIOS_SPEW
, "Established timings III\n");
236 int valid_cvt
= 1; /* just this block */
237 printk(BIOS_SPEW
, "CVT 3-byte code descriptor:\n");
239 c
->has_valid_cvt
= 0;
242 for (i
= 0; i
< 4; i
++)
243 valid_cvt
&= detailed_cvt_descriptor(x
+ 6
244 + (i
* 3), (i
== 0));
245 c
->has_valid_cvt
&= valid_cvt
;
250 printk(BIOS_SPEW
, "Color management data\n");
254 printk(BIOS_SPEW
, "More standard timings\n");
258 printk(BIOS_SPEW
, "Color point\n");
261 printk(BIOS_SPEW
, "Monitor name: %s\n",
262 extract_string(x
+ 5,
263 &c
->has_valid_string_termination
,
264 EDID_ASCII_STRING_LENGTH
));
268 int h_max_offset
= 0, h_min_offset
= 0;
269 int v_max_offset
= 0, v_min_offset
= 0;
271 c
->has_range_descriptor
= 1;
272 extra_info
.range_class
= "";
274 * XXX todo: implement feature flags, vtd blocks
275 * XXX check: ranges are well-formed; block termination
278 if (c
->claims_one_point_four
) {
290 c
->has_valid_range_descriptor
= 0;
294 * despite the values, this is not a bitfield.
297 case 0x00: /* default gtf */
298 extra_info
.range_class
= "GTF";
300 case 0x01: /* range limits only */
301 extra_info
.range_class
= "bare limits";
302 if (!c
->claims_one_point_four
)
303 c
->has_valid_range_descriptor
= 0;
305 case 0x02: /* secondary gtf curve */
306 extra_info
.range_class
= "GTF with icing";
309 extra_info
.range_class
= "CVT";
311 if (!c
->claims_one_point_four
)
312 c
->has_valid_range_descriptor
= 0;
314 default: /* invalid */
315 c
->has_valid_range_descriptor
= 0;
316 extra_info
.range_class
= "invalid";
320 if (x
[5] + v_min_offset
> x
[6] + v_max_offset
)
321 c
->has_valid_range_descriptor
= 0;
322 if (x
[7] + h_min_offset
> x
[8] + h_max_offset
)
323 c
->has_valid_range_descriptor
= 0;
325 "Monitor ranges (%s): %d-%dHz V, %d-%dkHz H",
326 extra_info
.range_class
,
327 x
[5] + v_min_offset
, x
[6] + v_max_offset
,
328 x
[7] + h_min_offset
, x
[8] + h_max_offset
);
331 ", max dotclock %dMHz\n", x
[9] * 10);
333 if (c
->claims_one_point_four
)
334 c
->has_valid_max_dotclock
= 0;
335 printk(BIOS_SPEW
, "\n");
339 int max_h_pixels
= 0;
341 printk(BIOS_SPEW
, "CVT version %d.%d\n",
342 x
[11] & 0xf0 >> 4, x
[11] & 0x0f);
345 int raw_offset
= (x
[12] & 0xfc) >> 2;
347 "Real max dotclock: %dKHz\n",
349 - (raw_offset
* 250));
350 if (raw_offset
>= 40)
351 c
->warning_excessive_dotclock_correction
= 1;
354 max_h_pixels
= x
[12] & 0x03;
356 max_h_pixels
|= x
[13];
360 "Max active pixels per line: %d\n",
364 "Supported aspect ratios: %s %s %s %s %s\n",
365 x
[14] & 0x80 ? "4:3" : "",
366 x
[14] & 0x40 ? "16:9" : "",
367 x
[14] & 0x20 ? "16:10" : "",
368 x
[14] & 0x10 ? "5:4" : "",
369 x
[14] & 0x08 ? "15:9" : "");
371 c
->has_valid_range_descriptor
= 0;
373 printk(BIOS_SPEW
, "Preferred aspect ratio: ");
374 switch ((x
[15] & 0xe0) >> 5) {
376 printk(BIOS_SPEW
, "4:3");
379 printk(BIOS_SPEW
, "16:9");
382 printk(BIOS_SPEW
, "16:10");
385 printk(BIOS_SPEW
, "5:4");
388 printk(BIOS_SPEW
, "15:9");
391 printk(BIOS_SPEW
, "(broken)");
394 printk(BIOS_SPEW
, "\n");
398 "Supports CVT standard blanking\n");
401 "Supports CVT reduced blanking\n");
404 c
->has_valid_range_descriptor
= 0;
408 "Supported display scaling:\n");
411 " Horizontal shrink\n");
414 " Horizontal stretch\n");
417 " Vertical shrink\n");
420 " Vertical stretch\n");
424 c
->has_valid_range_descriptor
= 0;
428 "Preferred vertical refresh: %d Hz\n",
431 c
->warning_zero_preferred_refresh
= 1;
435 * Slightly weird to return a global, but I've never
436 * seen any EDID block wth two range descriptors, so
443 * TODO: Two of these in a row, in the third and fourth
444 * slots, seems to be specified by SPWG:
445 * http://www.spwg.org/
447 strcpy(result_edid
->ascii_string
, extract_string(x
+ 5,
448 &c
->has_valid_string_termination
,
449 EDID_ASCII_STRING_LENGTH
));
450 printk(BIOS_SPEW
, "ASCII string: %s\n",
451 result_edid
->ascii_string
);
454 printk(BIOS_SPEW
, "Serial number: %s\n",
455 extract_string(x
+ 5,
456 &c
->has_valid_string_termination
,
457 EDID_ASCII_STRING_LENGTH
));
461 "Unknown monitor description type %d\n",
467 if (c
->seen_non_detailed_descriptor
&& !in_extension
)
468 c
->has_valid_descriptor_ordering
= 0;
470 /* Edid contains pixel clock in terms of 10KHz */
471 out
->mode
.pixel_clock
= (x
[0] + (x
[1] << 8)) * 10;
473 LVDS supports following pixel clocks
474 25000...112000 kHz: single channel
475 80000...224000 kHz: dual channel
476 There is some overlap in theoretically supported
477 pixel clock between single-channel and dual-channel.
478 In practice with current panels all panels
479 <= 75200 kHz: single channel
480 >= 97750 kHz: dual channel
481 We have no samples between those values, so put a
482 threshold at 95000 kHz. If we get anything over
483 95000 kHz with single channel, we can make this
484 more sofisticated but it's currently not needed.
486 out
->mode
.lvds_dual_channel
= (out
->mode
.pixel_clock
>= 95000);
487 extra_info
.x_mm
= (x
[12] + ((x
[14] & 0xF0) << 4));
488 extra_info
.y_mm
= (x
[13] + ((x
[14] & 0x0F) << 8));
489 out
->mode
.ha
= (x
[2] + ((x
[4] & 0xF0) << 4));
490 out
->mode
.hbl
= (x
[3] + ((x
[4] & 0x0F) << 8));
491 out
->mode
.hso
= (x
[8] + ((x
[11] & 0xC0) << 2));
492 out
->mode
.hspw
= (x
[9] + ((x
[11] & 0x30) << 4));
493 out
->mode
.hborder
= x
[15];
494 out
->mode
.va
= (x
[5] + ((x
[7] & 0xF0) << 4));
495 out
->mode
.vbl
= (x
[6] + ((x
[7] & 0x0F) << 8));
496 out
->mode
.vso
= ((x
[10] >> 4) + ((x
[11] & 0x0C) << 2));
497 out
->mode
.vspw
= ((x
[10] & 0x0F) + ((x
[11] & 0x03) << 4));
498 out
->mode
.vborder
= x
[16];
500 /* We assume rgb888 (32 bits per pixel) framebuffers by default.
501 * Chipsets that want something else will need to override this with
502 * another call to edid_set_framebuffer_bits_per_pixel(). As a cheap
503 * heuristic, assume that X86 systems require a 64-byte row alignment
504 * (since that seems to be true for most Intel chipsets). */
505 if (CONFIG(ARCH_X86
))
506 edid_set_framebuffer_bits_per_pixel(out
, 32, 64);
508 edid_set_framebuffer_bits_per_pixel(out
, 32, 0);
510 switch ((x
[17] & 0x18) >> 3) {
512 extra_info
.syncmethod
= " analog composite";
515 extra_info
.syncmethod
= " bipolar analog composite";
518 extra_info
.syncmethod
= " digital composite";
521 extra_info
.syncmethod
= "";
524 out
->mode
.pvsync
= (x
[17] & (1 << 2)) ? '+' : '-';
525 out
->mode
.phsync
= (x
[17] & (1 << 1)) ? '+' : '-';
526 switch (x
[17] & 0x61) {
528 extra_info
.stereo
= "field sequential L/R";
531 extra_info
.stereo
= "field sequential R/L";
534 extra_info
.stereo
= "interleaved right even";
537 extra_info
.stereo
= "interleaved left even";
540 extra_info
.stereo
= "four way interleaved";
543 extra_info
.stereo
= "side by side interleaved";
546 extra_info
.stereo
= "";
551 "Detailed mode (IN HEX): Clock %d KHz, %x mm x %x mm\n"
552 " %04x %04x %04x %04x hborder %x\n"
553 " %04x %04x %04x %04x vborder %x\n"
554 " %chsync %cvsync%s%s%s\n",
555 out
->mode
.pixel_clock
,
558 out
->mode
.ha
, out
->mode
.ha
+ out
->mode
.hso
,
559 out
->mode
.ha
+ out
->mode
.hso
+ out
->mode
.hspw
,
560 out
->mode
.ha
+ out
->mode
.hbl
, out
->mode
.hborder
,
561 out
->mode
.va
, out
->mode
.va
+ out
->mode
.vso
,
562 out
->mode
.va
+ out
->mode
.vso
+ out
->mode
.vspw
,
563 out
->mode
.va
+ out
->mode
.vbl
, out
->mode
.vborder
,
564 out
->mode
.phsync
, out
->mode
.pvsync
,
565 extra_info
.syncmethod
, x
[17] & 0x80 ? " interlaced" : "",
568 if (!c
->did_detailed_timing
) {
569 printk(BIOS_SPEW
, "Did detailed timing\n");
570 c
->did_detailed_timing
= 1;
578 do_checksum(unsigned char *x
)
581 printk(BIOS_SPEW
, "Checksum: 0x%hhx", x
[0x7f]);
583 unsigned char sum
= 0;
585 for (i
= 0; i
< 128; i
++)
588 printk(BIOS_SPEW
, " (should be 0x%hhx)",
589 (unsigned char)(x
[0x7f] - sum
));
592 printk(BIOS_SPEW
, " (valid)");
595 printk(BIOS_SPEW
, "\n");
602 audio_format(unsigned char x
)
605 case 0: return "RESERVED";
606 case 1: return "Linear PCM";
607 case 2: return "AC-3";
608 case 3: return "MPEG 1 (Layers 1 & 2)";
609 case 4: return "MPEG 1 Layer 3 (MP3)";
610 case 5: return "MPEG2 (multichannel)";
611 case 6: return "AAC";
612 case 7: return "DTS";
613 case 8: return "ATRAC";
614 case 9: return "One Bit Audio";
615 case 10: return "Dolby Digital+";
616 case 11: return "DTS-HD";
617 case 12: return "MAT (MLP)";
618 case 13: return "DST";
619 case 14: return "WMA Pro";
620 case 15: return "RESERVED";
622 return "BROKEN"; /* can't happen */
626 cea_audio_block(unsigned char *x
)
629 int length
= x
[0] & 0x1f;
632 printk(BIOS_SPEW
, "Broken CEA audio block length %d\n", length
);
633 /* XXX non-conformant */
637 for (i
= 1; i
< length
; i
+= 3) {
638 format
= (x
[i
] & 0x78) >> 3;
639 printk(BIOS_SPEW
, " %s, max channels %d\n",
640 audio_format(format
), x
[i
] & 0x07);
642 " Supported sample rates (kHz):%s%s%s%s%s%s%s\n",
643 (x
[i
+1] & 0x40) ? " 192" : "",
644 (x
[i
+1] & 0x20) ? " 176.4" : "",
645 (x
[i
+1] & 0x10) ? " 96" : "",
646 (x
[i
+1] & 0x08) ? " 88.2" : "",
647 (x
[i
+1] & 0x04) ? " 48" : "",
648 (x
[i
+1] & 0x02) ? " 44.1" : "",
649 (x
[i
+1] & 0x01) ? " 32" : "");
652 " Supported sample sizes (bits):%s%s%s\n",
653 (x
[2] & 0x04) ? " 24" : "",
654 (x
[2] & 0x02) ? " 20" : "",
655 (x
[2] & 0x01) ? " 16" : "");
656 } else if (format
<= 8) {
658 " Maximum bit rate: %d kHz\n", x
[2] * 8);
664 cea_video_block(unsigned char *x
)
667 int length
= x
[0] & 0x1f;
669 for (i
= 1; i
< length
; i
++)
670 printk(BIOS_SPEW
, " VIC %02d %s\n", x
[i
] & 0x7f,
671 x
[i
] & 0x80 ? "(native)" : "");
675 cea_hdmi_block(struct edid
*out
, unsigned char *x
)
677 int length
= x
[0] & 0x1f;
679 out
->hdmi_monitor_detected
= 1;
681 printk(BIOS_SPEW
, " (HDMI)\n");
683 " Source physical address %d.%d.%d.%d\n",
684 x
[4] >> 4, x
[4] & 0x0f, x
[5] >> 4, x
[5] & 0x0f);
688 printk(BIOS_SPEW
, " Supports_AI\n");
690 printk(BIOS_SPEW
, " DC_48bit\n");
692 printk(BIOS_SPEW
, " DC_36bit\n");
694 printk(BIOS_SPEW
, " DC_30bit\n");
696 printk(BIOS_SPEW
, " DC_Y444\n");
699 printk(BIOS_SPEW
, " DVI_Dual\n");
703 printk(BIOS_SPEW
, " Maximum TMDS clock: %dMHz\n", x
[7] * 5);
705 /* XXX the walk here is really ugly, and needs to be length-checked */
710 printk(BIOS_SPEW
, " Video latency: %d\n", x
[9 + b
]);
711 printk(BIOS_SPEW
, " Audio latency: %d\n", x
[10 + b
]);
717 " Interlaced video latency: %d\n", x
[9 + b
]);
719 " Interlaced audio latency: %d\n",
725 int mask
= 0, formats
= 0;
727 printk(BIOS_SPEW
, " Extended HDMI video details:\n");
729 printk(BIOS_SPEW
, " 3D present\n");
730 if ((x
[9 + b
] & 0x60) == 0x20) {
732 " All advertised VICs are 3D-capable\n");
735 if ((x
[9 + b
] & 0x60) == 0x40) {
737 " 3D-capable-VIC mask present\n");
741 switch (x
[9 + b
] & 0x18) {
745 printk(BIOS_SPEW
, " Base EDID image size is aspect ratio\n");
748 printk(BIOS_SPEW
, " Base EDID image size is in units of 1cm\n");
751 printk(BIOS_SPEW
, " Base EDID image size is in units of 5cm\n");
754 len_xx
= (x
[10 + b
] & 0xe0) >> 5;
755 len_3d
= (x
[10 + b
] & 0x1f) >> 0;
759 printk(BIOS_SPEW
, " Skipping %d bytes that HDMI refuses to publicly"
760 " document\n", len_xx
);
767 printk(BIOS_SPEW
, " Side-by-side 3D supported\n");
768 if (x
[10 + b
] & 0x40)
769 printk(BIOS_SPEW
, " Top-and-bottom 3D supported\n");
770 if (x
[10 + b
] & 0x01)
771 printk(BIOS_SPEW
, " Frame-packing 3D supported\n");
778 /* worst bit ordering ever */
779 for (i
= 0; i
< 8; i
++)
780 if (x
[10 + b
] & (1 << i
))
783 for (i
= 0; i
< 8; i
++)
784 if (x
[9 + b
] & (1 << i
))
787 printk(BIOS_SPEW
, "\n");
792 * XXX list of nibbles:
795 * (optionally: 3D_Detail_X and reserved)
799 /* Tell static analysis we know index b is left unused. */
805 cea_block(struct edid
*out
, unsigned char *x
)
809 switch ((x
[0] & 0xe0) >> 5) {
811 printk(BIOS_SPEW
, " Audio data block\n");
815 printk(BIOS_SPEW
, " Video data block\n");
819 /* yes really, endianness lols */
820 oui
= (x
[3] << 16) + (x
[2] << 8) + x
[1];
821 printk(BIOS_SPEW
, " Vendor-specific data block, OUI %06x",
824 cea_hdmi_block(out
, x
);
826 printk(BIOS_SPEW
, "\n");
829 printk(BIOS_SPEW
, " Speaker allocation data block\n");
832 printk(BIOS_SPEW
, " VESA DTC data block\n");
835 printk(BIOS_SPEW
, " Extended tag: ");
838 printk(BIOS_SPEW
, "video capability data block\n");
841 printk(BIOS_SPEW
, "vendor-specific video data block\n");
845 "VESA video display device information data block\n");
848 printk(BIOS_SPEW
, "VESA video data block\n");
851 printk(BIOS_SPEW
, "HDMI video data block\n");
854 printk(BIOS_SPEW
, "Colorimetry data block\n");
857 printk(BIOS_SPEW
, "CEA miscellaneous audio fields\n");
860 printk(BIOS_SPEW
, "Vendor-specific audio data block\n");
863 printk(BIOS_SPEW
, "HDMI audio data block\n");
866 if (x
[1] >= 6 && x
[1] <= 15)
868 "Reserved video block (%02x)\n", x
[1]);
869 else if (x
[1] >= 19 && x
[1] <= 31)
871 "Reserved audio block (%02x)\n", x
[1]);
873 printk(BIOS_SPEW
, "Unknown (%02x)\n", x
[1]);
879 int tag
= (*x
& 0xe0) >> 5;
880 int length
= *x
& 0x1f;
882 " Unknown tag %d, length %d (raw %02x)\n",
890 parse_cea(struct edid
*out
, unsigned char *x
, struct edid_context
*c
)
895 unsigned char *detailed
;
899 if (version
== 1 && x
[3] != 0)
907 "%d 8-byte timing descriptors\n",
909 else if (version
== 3) {
912 "%d bytes of CEA data\n", offset
- 4);
913 for (i
= 4; i
< offset
; i
+= (x
[i
] & 0x1f) + 1)
914 cea_block(out
, x
+ i
);
920 "Underscans PC formats by default\n");
923 "Basic audio support\n");
926 "Supports YCbCr 4:4:4\n");
929 "Supports YCbCr 4:2:2\n");
931 "%d native detailed modes\n",
935 for (detailed
= x
+ offset
; detailed
+ 18 < x
+ 127;
938 detailed_block(out
, detailed
, 1, c
);
941 c
->has_valid_checksum
&= do_checksum(x
);
945 /* generic extension code */
948 extension_version(struct edid
*out
, unsigned char *x
)
950 printk(BIOS_SPEW
, "Extension version: %d\n", x
[1]);
954 parse_extension(struct edid
*out
, unsigned char *x
, struct edid_context
*c
)
956 int conformant_extension
= 0;
957 printk(BIOS_SPEW
, "\n");
961 printk(BIOS_SPEW
, "CEA extension block\n");
962 extension_version(out
, x
);
963 conformant_extension
= parse_cea(out
, x
, c
);
966 printk(BIOS_SPEW
, "VTB extension block\n");
969 printk(BIOS_SPEW
, "DI extension block\n");
972 printk(BIOS_SPEW
, "LS extension block\n");
975 printk(BIOS_SPEW
, "DPVL extension block\n");
978 printk(BIOS_SPEW
, "Block map\n");
981 printk(BIOS_SPEW
, "Manufacturer-specific extension block\n");
984 printk(BIOS_SPEW
, "Unknown extension block\n");
988 printk(BIOS_SPEW
, "\n");
990 return conformant_extension
;
993 static const struct {
995 } established_timings
[] = {
1005 /* 0x24 bit 7 - 0 */
1018 static void print_subsection(const char *name
, unsigned char *edid
, int start
,
1023 printk(BIOS_SPEW
, "%s:", name
);
1024 for (i
= strlen(name
); i
< 15; i
++)
1025 printk(BIOS_SPEW
, " ");
1026 for (i
= start
; i
<= end
; i
++)
1027 printk(BIOS_SPEW
, " %02x", edid
[i
]);
1028 printk(BIOS_SPEW
, "\n");
1031 static void dump_breakdown(unsigned char *edid
)
1033 printk(BIOS_SPEW
, "Extracted contents:\n");
1034 print_subsection("header", edid
, 0, 7);
1035 print_subsection("serial number", edid
, 8, 17);
1036 print_subsection("version", edid
, 18, 19);
1037 print_subsection("basic params", edid
, 20, 24);
1038 print_subsection("chroma info", edid
, 25, 34);
1039 print_subsection("established", edid
, 35, 37);
1040 print_subsection("standard", edid
, 38, 53);
1041 print_subsection("descriptor 1", edid
, 54, 71);
1042 print_subsection("descriptor 2", edid
, 72, 89);
1043 print_subsection("descriptor 3", edid
, 90, 107);
1044 print_subsection("descriptor 4", edid
, 108, 125);
1045 print_subsection("extensions", edid
, 126, 126);
1046 print_subsection("checksum", edid
, 127, 127);
1047 printk(BIOS_SPEW
, "\n");
1051 * Lookup table of some well-known modes that can be useful in case the
1052 * auto-detected mode is unsuitable.
1053 * ha = hdisplay; va = vdisplay;
1054 * hbl = htotal - hdisplay; vbl = vtotal - vdisplay;
1055 * hso = hsync_start - hdsiplay; vso = vsync_start - vdisplay;
1056 * hspw = hsync_end - hsync_start; vspw = vsync_end - vsync_start;
1058 static struct edid_mode known_modes
[NUM_KNOWN_MODES
] = {
1059 [EDID_MODE_640x480_60Hz
] = {
1060 .name
= "640x480@60Hz", .pixel_clock
= 25200, .refresh
= 60,
1061 .ha
= 640, .hbl
= 160, .hso
= 16, .hspw
= 96,
1062 .va
= 480, .vbl
= 45, .vso
= 10, .vspw
= 2,
1063 .phsync
= '-', .pvsync
= '-' },
1064 [EDID_MODE_720x480_60Hz
] = {
1065 .name
= "720x480@60Hz", .pixel_clock
= 27000, .refresh
= 60,
1066 .ha
= 720, .hbl
= 138, .hso
= 16, .hspw
= 62,
1067 .va
= 480, .vbl
= 45, .vso
= 9, .vspw
= 6,
1068 .phsync
= '-', .pvsync
= '-' },
1069 [EDID_MODE_1280x720_60Hz
] = {
1070 .name
= "1280x720@60Hz", .pixel_clock
= 74250, .refresh
= 60,
1071 .ha
= 1280, .hbl
= 370, .hso
= 110, .hspw
= 40,
1072 .va
= 720, .vbl
= 30, .vso
= 5, .vspw
= 20,
1073 .phsync
= '+', .pvsync
= '+' },
1074 [EDID_MODE_1920x1080_60Hz
] = {
1075 .name
= "1920x1080@60Hz", .pixel_clock
= 148500, .refresh
= 60,
1076 .ha
= 1920, .hbl
= 280, .hso
= 88, .hspw
= 44,
1077 .va
= 1080, .vbl
= 45, .vso
= 4, .vspw
= 5,
1078 .phsync
= '+', .pvsync
= '+' },
1081 int set_display_mode(struct edid
*edid
, enum edid_modes mode
)
1083 if (mode
== EDID_MODE_AUTO
)
1086 if (edid
->mode_is_supported
[mode
]) {
1087 printk(BIOS_DEBUG
, "Forcing mode %s\n", known_modes
[mode
].name
);
1088 edid
->mode
= known_modes
[mode
];
1092 printk(BIOS_ERR
, "Requested display mode not supported.\n");
1097 * Given a raw edid bloc, decode it into a form
1098 * that other parts of coreboot can use -- mainly
1099 * graphics bringup functions. The raw block is
1100 * required to be 128 bytes long, per the standard,
1101 * but we have no way of checking this minimum length.
1102 * We accept what we are given.
1104 int decode_edid(unsigned char *edid
, int size
, struct edid
*out
)
1107 struct edid_context c
= {
1109 .has_valid_dummy_block
= 1,
1110 .has_valid_descriptor_ordering
= 1,
1111 .has_valid_detailed_blocks
= 1,
1112 .has_valid_descriptor_pad
= 1,
1113 .has_valid_range_descriptor
= 1,
1114 .has_valid_max_dotclock
= 1,
1115 .has_valid_string_termination
= 1,
1116 .conformant
= EDID_CONFORMANT
,
1120 printk(BIOS_ERR
, "No EDID found\n");
1124 dump_breakdown(edid
);
1126 if (memcmp(edid
, "\x00\xFF\xFF\xFF\xFF\xFF\xFF\x00", 8)) {
1127 printk(BIOS_ERR
, "No header found\n");
1131 memset(out
, 0, sizeof(*out
));
1133 if (manufacturer_name(edid
+ 0x08, out
->manufacturer_name
))
1134 c
.manufacturer_name_well_formed
= 1;
1136 extra_info
.model
= (unsigned short)(edid
[0x0A] + (edid
[0x0B] << 8));
1137 extra_info
.serial
= (unsigned int)(edid
[0x0C] + (edid
[0x0D] << 8)
1138 + (edid
[0x0E] << 16) + (edid
[0x0F] << 24));
1140 printk(BIOS_SPEW
, "Manufacturer: %s Model %x Serial Number %u\n",
1141 out
->manufacturer_name
,
1142 (unsigned short)(edid
[0x0A] + (edid
[0x0B] << 8)),
1143 (unsigned int)(edid
[0x0C] + (edid
[0x0D] << 8)
1144 + (edid
[0x0E] << 16) + (edid
[0x0F] << 24)));
1145 /* XXX need manufacturer ID table */
1147 if (edid
[0x10] < 55 || edid
[0x10] == 0xff) {
1148 c
.has_valid_week
= 1;
1149 if (edid
[0x11] > 0x0f) {
1150 if (edid
[0x10] == 0xff) {
1151 c
.has_valid_year
= 1;
1153 "Made week %hhd of model year %hhd\n",
1154 edid
[0x10], edid
[0x11]);
1155 extra_info
.week
= edid
[0x10];
1156 extra_info
.year
= edid
[0x11];
1158 /* we know it's at least 2013, when this code
1161 if (edid
[0x11] + 90 <= 2013) {
1162 c
.has_valid_year
= 1;
1164 "Made week %hhd of %d\n",
1165 edid
[0x10], edid
[0x11] + 1990);
1166 extra_info
.week
= edid
[0x10];
1167 extra_info
.year
= edid
[0x11] + 1990;
1173 printk(BIOS_SPEW
, "EDID version: %hhd.%hhd\n", edid
[0x12], edid
[0x13]);
1174 extra_info
.version
[0] = edid
[0x12];
1175 extra_info
.version
[1] = edid
[0x13];
1177 if (edid
[0x12] == 1) {
1178 if (edid
[0x13] > 4) {
1180 "Claims > 1.4, assuming 1.4 conformance\n");
1183 switch (edid
[0x13]) {
1185 c
.claims_one_point_four
= 1;
1188 c
.claims_one_point_three
= 1;
1191 c
.claims_one_point_two
= 1;
1194 c
.claims_one_point_oh
= 1;
1198 /* display section */
1199 if (edid
[0x14] & 0x80) {
1200 int conformance_mask
;
1202 printk(BIOS_SPEW
, "Digital display\n");
1203 if (c
.claims_one_point_four
) {
1204 conformance_mask
= 0;
1205 if ((edid
[0x14] & 0x70) == 0x00)
1206 printk(BIOS_SPEW
, "Color depth is undefined\n");
1207 else if ((edid
[0x14] & 0x70) == 0x70)
1208 c
.nonconformant_digital_display
= 1;
1211 "%d bits per primary color channel\n",
1212 ((edid
[0x14] & 0x70) >> 3) + 4);
1213 out
->panel_bits_per_color
= ((edid
[0x14] & 0x70) >> 3)
1215 out
->panel_bits_per_pixel
= 3*out
->panel_bits_per_color
;
1217 switch (edid
[0x14] & 0x0f) {
1220 "Digital interface is not defined\n");
1223 printk(BIOS_SPEW
, "DVI interface\n");
1226 printk(BIOS_SPEW
, "HDMI-a interface\n");
1229 printk(BIOS_SPEW
, "HDMI-b interface\n");
1232 printk(BIOS_SPEW
, "MDDI interface\n");
1235 printk(BIOS_SPEW
, "DisplayPort interface\n");
1238 c
.nonconformant_digital_display
= 1;
1241 extra_info
.type
= edid
[0x14] & 0x0f;
1242 } else if (c
.claims_one_point_two
) {
1243 conformance_mask
= 0x7E;
1244 if (edid
[0x14] & 0x01)
1245 printk(BIOS_SPEW
, "DFP 1.x compatible TMDS\n");
1247 conformance_mask
= 0x7F;
1249 if (!c
.nonconformant_digital_display
)
1250 c
.nonconformant_digital_display
= edid
[0x14]
1252 extra_info
.nonconformant
= c
.nonconformant_digital_display
;
1255 int voltage
= (edid
[0x14] & 0x60) >> 5;
1256 int sync
= (edid
[0x14] & 0x0F);
1257 extra_info
.voltage
= voltage
;
1258 extra_info
.sync
= sync
;
1260 printk(BIOS_SPEW
, "Analog display, Input voltage level: %s V\n",
1261 voltage
== 3 ? "0.7/0.7" :
1262 voltage
== 2 ? "1.0/0.4" :
1263 voltage
== 1 ? "0.714/0.286" :
1266 if (c
.claims_one_point_four
) {
1267 if (edid
[0x14] & 0x10)
1269 "Blank-to-black setup/pedestal\n");
1272 "Blank level equals black level\n");
1273 } else if (edid
[0x14] & 0x10) {
1275 * XXX this is just the X text. 1.3 says "if set,
1276 * display expects a blank-to-black setup or pedestal
1277 * per appropriate Signal Level Standard". Whatever
1280 printk(BIOS_SPEW
, "Configurable signal levels\n");
1283 printk(BIOS_SPEW
, "Sync: %s%s%s%s\n",
1284 sync
& 0x08 ? "Separate " : "",
1285 sync
& 0x04 ? "Composite " : "",
1286 sync
& 0x02 ? "SyncOnGreen " : "",
1287 sync
& 0x01 ? "Serration " : "");
1291 if (edid
[0x15] && edid
[0x16]) {
1292 printk(BIOS_SPEW
, "Maximum image size: %d cm x %d cm\n",
1293 edid
[0x15], edid
[0x16]);
1294 } else if (c
.claims_one_point_four
&& (edid
[0x15] || edid
[0x16])) {
1295 if (edid
[0x15]) { /* edid[0x15] != 0 && edid[0x16] == 0 */
1296 unsigned int ratio
= 100000/(edid
[0x15] + 99);
1298 "Aspect ratio is %u.%03u (landscape)\n",
1299 ratio
/ 1000, ratio
% 1000);
1300 } else { /* edid[0x15] == 0 && edid[0x16] != 0 */
1301 unsigned int ratio
= 100000/(edid
[0x16] + 99);
1303 "Aspect ratio is %u.%03u (portrait)\n",
1304 ratio
/ 1000, ratio
% 1000);
1307 /* Either or both can be zero for 1.3 and before */
1308 printk(BIOS_SPEW
, "Image size is variable\n");
1311 if (edid
[0x17] == 0xff) {
1312 if (c
.claims_one_point_four
)
1314 "Gamma is defined in an extension block\n");
1316 /* XXX Technically 1.3 doesn't say this... */
1317 printk(BIOS_SPEW
, "Gamma: 1.0\n");
1319 printk(BIOS_SPEW
, "Gamma: %d%%\n", ((edid
[0x17] + 100)));
1320 printk(BIOS_SPEW
, "Check DPMS levels\n");
1321 if (edid
[0x18] & 0xE0) {
1322 printk(BIOS_SPEW
, "DPMS levels:");
1323 if (edid
[0x18] & 0x80)
1324 printk(BIOS_SPEW
, " Standby");
1325 if (edid
[0x18] & 0x40)
1326 printk(BIOS_SPEW
, " Suspend");
1327 if (edid
[0x18] & 0x20)
1328 printk(BIOS_SPEW
, " Off");
1329 printk(BIOS_SPEW
, "\n");
1332 /* FIXME: this is from 1.4 spec, check earlier */
1334 switch (edid
[0x18] & 0x18) {
1336 printk(BIOS_SPEW
, "Monochrome or grayscale display\n");
1339 printk(BIOS_SPEW
, "RGB color display\n");
1342 printk(BIOS_SPEW
, "Non-RGB color display\n");
1345 printk(BIOS_SPEW
, "Undefined display color type\n");
1349 printk(BIOS_SPEW
, "Supported color formats: RGB 4:4:4");
1350 if (edid
[0x18] & 0x10)
1351 printk(BIOS_SPEW
, ", YCrCb 4:4:4");
1352 if (edid
[0x18] & 0x08)
1353 printk(BIOS_SPEW
, ", YCrCb 4:2:2");
1354 printk(BIOS_SPEW
, "\n");
1357 if (edid
[0x18] & 0x04)
1359 "Default (sRGB) color space is primary color space\n");
1360 if (edid
[0x18] & 0x02) {
1362 "First detailed timing is preferred timing\n");
1363 c
.has_preferred_timing
= 1;
1365 if (edid
[0x18] & 0x01)
1367 "Supports GTF timings within operating range\n");
1369 /* XXX color section */
1371 printk(BIOS_SPEW
, "Established timings supported:\n");
1372 /* it's not yet clear we want all this stuff in the edid struct.
1375 for (i
= 0; i
< 17; i
++) {
1376 if (edid
[0x23 + i
/ 8] & (1 << (7 - i
% 8))) {
1377 printk(BIOS_SPEW
, " %dx%d@%dHz\n",
1378 established_timings
[i
].x
,
1379 established_timings
[i
].y
,
1380 established_timings
[i
].refresh
);
1382 for (j
= 0; j
< NUM_KNOWN_MODES
; j
++) {
1383 if (known_modes
[j
].ha
==
1384 established_timings
[i
].x
1385 && known_modes
[j
].va
==
1386 established_timings
[i
].y
1387 && known_modes
[j
].refresh
==
1388 established_timings
[i
].refresh
)
1389 out
->mode_is_supported
[j
] = 1;
1395 printk(BIOS_SPEW
, "Standard timings supported:\n");
1396 for (i
= 0; i
< 8; i
++) {
1397 uint8_t b1
= edid
[0x26 + i
* 2], b2
= edid
[0x26 + i
* 2 + 1];
1398 unsigned int x
, y
= 0, refresh
;
1400 if (b1
== 0x01 && b2
== 0x01)
1405 "non-conformant standard timing (0 horiz)\n");
1409 switch ((b2
>> 6) & 0x3) {
1411 if (c
.claims_one_point_three
)
1426 refresh
= 60 + (b2
& 0x3f);
1428 printk(BIOS_SPEW
, " %dx%d@%dHz\n", x
, y
, refresh
);
1429 for (j
= 0; j
< NUM_KNOWN_MODES
; j
++) {
1430 if (known_modes
[j
].ha
== x
&& known_modes
[j
].va
== y
&&
1431 known_modes
[j
].refresh
== refresh
)
1432 out
->mode_is_supported
[j
] = 1;
1436 /* detailed timings */
1437 printk(BIOS_SPEW
, "Detailed timings\n");
1438 for (i
= 0; i
< 4; i
++) {
1439 c
.has_valid_detailed_blocks
&= detailed_block(
1440 out
, edid
+ 0x36 + i
* 18, 0, &c
);
1441 if (i
== 0 && c
.has_preferred_timing
1442 && !c
.did_detailed_timing
) {
1443 /* not really accurate... */
1444 c
.has_preferred_timing
= 0;
1448 /* check this, 1.4 verification guide says otherwise */
1450 printk(BIOS_SPEW
, "Has %d extension blocks\n", edid
[0x7e]);
1451 /* 2 is impossible because of the block map */
1452 if (edid
[0x7e] != 2)
1453 c
.has_valid_extension_count
= 1;
1455 c
.has_valid_extension_count
= 1;
1458 printk(BIOS_SPEW
, "Checksum\n");
1459 c
.has_valid_checksum
= do_checksum(edid
);
1461 /* EDID v2.0 has a larger blob (256 bytes) and may have some problem in
1462 * the extension parsing loop below. Since v2.0 was quickly deprecated
1463 * by v1.3 and we are unlikely to use any EDID 2.0 panels, we ignore
1464 * that case now and can fix it when we need to use a real 2.0 panel.
1466 for (i
= 128; i
< size
; i
+= 128)
1467 c
.nonconformant_extension
+=
1468 parse_extension(out
, &edid
[i
], &c
);
1470 if (c
.claims_one_point_four
) {
1471 if (c
.nonconformant_digital_display
||
1472 !c
.has_valid_string_termination
||
1473 !c
.has_valid_descriptor_pad
||
1474 !c
.has_preferred_timing
) {
1475 c
.conformant
= EDID_NOT_CONFORMANT
;
1477 "EDID block does NOT conform to EDID 1.4!\n");
1480 if (c
.nonconformant_digital_display
)
1482 "\tDigital display field contains garbage: %x\n",
1483 c
.nonconformant_digital_display
);
1484 if (!c
.has_valid_string_termination
)
1486 "\tDetailed block string not properly terminated\n");
1487 if (!c
.has_valid_descriptor_pad
)
1489 "\tInvalid descriptor block padding\n");
1490 if (!c
.has_preferred_timing
)
1491 printk(BIOS_ERR
, "\tMissing preferred timing\n");
1492 } else if (c
.claims_one_point_three
) {
1493 if (c
.nonconformant_digital_display
||
1494 !c
.has_valid_string_termination
||
1495 !c
.has_valid_descriptor_pad
||
1496 !c
.has_preferred_timing
) {
1497 c
.conformant
= EDID_NOT_CONFORMANT
;
1500 * According to E-EDID (EDIDv1.3), has_name_descriptor and
1501 * has_range_descriptor are both required. These fields are
1502 * optional in v1.4. However some v1.3 panels (Ex, B133XTN01.3)
1503 * don't have them. As a workaround, we only print warning
1506 if (c
.conformant
== EDID_NOT_CONFORMANT
)
1508 "EDID block does NOT conform to EDID 1.3!\n");
1509 else if (!c
.has_name_descriptor
|| !c
.has_range_descriptor
)
1510 printk(BIOS_WARNING
, "WARNING: EDID block does NOT "
1511 "fully conform to EDID 1.3.\n");
1513 if (c
.nonconformant_digital_display
)
1515 "\tDigital display field contains garbage: %x\n",
1516 c
.nonconformant_digital_display
);
1517 if (!c
.has_name_descriptor
)
1518 printk(BIOS_ERR
, "\tMissing name descriptor\n");
1519 if (!c
.has_preferred_timing
)
1520 printk(BIOS_ERR
, "\tMissing preferred timing\n");
1521 if (!c
.has_range_descriptor
)
1522 printk(BIOS_ERR
, "\tMissing monitor ranges\n");
1523 /* Might be more than just 1.3 */
1524 if (!c
.has_valid_descriptor_pad
)
1526 "\tInvalid descriptor block padding\n");
1527 if (!c
.has_valid_string_termination
) /* Likewise */
1529 "\tDetailed block string not properly terminated\n");
1530 } else if (c
.claims_one_point_two
) {
1531 if (c
.nonconformant_digital_display
||
1532 !c
.has_valid_string_termination
) {
1533 c
.conformant
= EDID_NOT_CONFORMANT
;
1535 "EDID block does NOT conform to EDID 1.2!\n");
1537 if (c
.nonconformant_digital_display
)
1539 "\tDigital display field contains garbage: %x\n",
1540 c
.nonconformant_digital_display
);
1541 if (!c
.has_valid_string_termination
)
1543 "\tDetailed block string not properly terminated\n");
1544 } else if (c
.claims_one_point_oh
) {
1545 if (c
.seen_non_detailed_descriptor
) {
1546 c
.conformant
= EDID_NOT_CONFORMANT
;
1548 "EDID block does NOT conform to EDID 1.0!\n");
1550 if (c
.seen_non_detailed_descriptor
)
1552 "\tHas descriptor blocks other than detailed timings\n");
1555 if (c
.nonconformant_extension
||
1556 !c
.has_valid_checksum
||
1558 !c
.has_valid_year
||
1559 !c
.has_valid_week
||
1560 !c
.has_valid_detailed_blocks
||
1561 !c
.has_valid_dummy_block
||
1562 !c
.has_valid_extension_count
||
1563 !c
.has_valid_descriptor_ordering
||
1564 !c
.has_valid_range_descriptor
||
1565 !c
.manufacturer_name_well_formed
) {
1566 c
.conformant
= EDID_NOT_CONFORMANT
;
1567 printk(BIOS_ERR
, "EDID block does not conform at all!\n");
1568 if (c
.nonconformant_extension
)
1570 "\tHas %d nonconformant extension block(s)\n",
1571 c
.nonconformant_extension
);
1572 if (!c
.has_valid_checksum
)
1573 printk(BIOS_ERR
, "\tBlock has broken checksum\n");
1574 if (!c
.has_valid_cvt
)
1575 printk(BIOS_ERR
, "\tBroken 3-byte CVT blocks\n");
1576 if (!c
.has_valid_year
)
1577 printk(BIOS_ERR
, "\tBad year of manufacture\n");
1578 if (!c
.has_valid_week
)
1579 printk(BIOS_ERR
, "\tBad week of manufacture\n");
1580 if (!c
.has_valid_detailed_blocks
)
1582 "\tDetailed blocks filled with garbage\n");
1583 if (!c
.has_valid_dummy_block
)
1584 printk(BIOS_ERR
, "\tDummy block filled with garbage\n");
1585 if (!c
.has_valid_extension_count
)
1587 "\tImpossible extension block count\n");
1588 if (!c
.manufacturer_name_well_formed
)
1590 "\tManufacturer name field contains garbage\n");
1591 if (!c
.has_valid_descriptor_ordering
)
1593 "\tInvalid detailed timing descriptor ordering\n");
1594 if (!c
.has_valid_range_descriptor
)
1596 "\tRange descriptor contains garbage\n");
1597 if (!c
.has_valid_max_dotclock
)
1599 "\tEDID 1.4 block does not set max dotclock\n");
1602 if (c
.warning_excessive_dotclock_correction
)
1604 "Warning: CVT block corrects dotclock by more than 9.75MHz\n");
1605 if (c
.warning_zero_preferred_refresh
)
1607 "Warning: CVT block does not set preferred refresh rate\n");
1608 return c
.conformant
;
1612 * Notes on panel extensions: (TODO, implement me in the code)
1614 * EPI: http://www.epi-standard.org/fileadmin/spec/EPI_Specification1.0.pdf
1615 * at offset 0x6c (fourth detailed block): (all other bits reserved)
1616 * 0x6c: 00 00 00 0e 00
1617 * 0x71: bit 6-5: data color mapping (00 conventional/fpdi/vesa, 01 openldi)
1618 * bit 4-3: pixels per clock (00 1, 01 2, 10 4, 11 reserved)
1619 * bit 2-0: bits per pixel (000 18, 001 24, 010 30, else reserved)
1620 * 0x72: bit 5: FPSCLK polarity (0 normal 1 inverted)
1621 * bit 4: DE polarity (0 high active 1 low active)
1622 * bit 3-0: interface (0000 LVDS TFT
1623 * 0001 mono STN 4/8bit
1624 * 0010 color STN 8/16 bit
1629 * 0x73: bit 1: horizontal display mode (0 normal 1 right/left reverse)
1630 * bit 0: vertical display mode (0 normal 1 up/down reverse)
1631 * 0x74: bit 7-4: total poweroff seq delay (0000 vga controller default
1632 * else time in 10ms (10ms to 150ms))
1633 * bit 3-0: total poweron seq delay (as above)
1634 * 0x75: contrast power on/off seq delay, same as 0x74
1635 * 0x76: bit 7: backlight control enable (1 means this field is valid)
1636 * bit 6: backlight enabled at boot (0 on 1 off)
1637 * bit 5-0: backlight brightness control steps (0..63)
1638 * 0x77: bit 7: contrast control, same bit pattern as 0x76 except bit 6 resvd
1639 * 0x78 - 0x7c: reserved
1640 * 0x7d: bit 7-4: EPI descriptor major version (1)
1641 * bit 3-0: EPI descriptor minor version (0)
1645 * SPWG: http://www.spwg.org/spwg_spec_version3.8_3-14-2007.pdf
1647 * Since these are "dummy" blocks, terminate with 0a 20 20 20 ... as usual
1649 * detailed descriptor 3:
1650 * 0x5a - 0x5e: 00 00 00 fe 00
1651 * 0x5f - 0x63: PC maker part number
1652 * 0x64: LCD supplier revision #
1653 * 0x65 - 0x6b: manufacturer part number
1655 * detailed descriptor 4:
1656 * 0x6c - 0x70: 00 00 00 fe 00
1657 * 0x71 - 0x78: smbus nits values (whut)
1658 * 0x79: number of lvds channels (1 or 2)
1659 * 0x7A: panel self test (1 if present)
1660 * and then dummy terminator
1662 * SPWG also says something strange about the LSB of detailed descriptor 1:
1663 * "LSB is set to "1" if panel is DE-timing only. H/V can be ignored."
1666 /* Set the framebuffer bits-per-pixel, recalculating all dependent values. */
1667 void edid_set_framebuffer_bits_per_pixel(struct edid
*edid
, int fb_bpp
,
1668 int row_byte_alignment
)
1670 /* Caller should pass a supported value, everything else is BUG(). */
1671 assert(fb_bpp
== 32 || fb_bpp
== 24 || fb_bpp
== 16);
1672 row_byte_alignment
= MAX(row_byte_alignment
, 1);
1674 edid
->framebuffer_bits_per_pixel
= fb_bpp
;
1675 edid
->bytes_per_line
= ALIGN_UP(edid
->mode
.ha
*
1676 DIV_ROUND_UP(fb_bpp
, 8), row_byte_alignment
);
1677 edid
->x_resolution
= edid
->bytes_per_line
/ (fb_bpp
/ 8);
1678 edid
->y_resolution
= edid
->mode
.va
;