releases/upstream/2.6.26-rc1/0006-ACPI-thinkpad-acpi-fix-brightness-dimming-control.patch

   1 From e11aecf1379e7c4a0293182096e38e5a336696b2 Mon Sep 17 00:00:00 2001
   2 From: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
   3 Date: Sat, 26 Apr 2008 01:02:21 -0300
   4 Subject: ACPI: thinkpad-acpi: fix brightness dimming control bug
   5
   6 ibm-acpi and thinkpad-acpi did not know about bit 5 of the EC backlight
   7 level control register (EC 0x31), so it was always forced to zero on
   8 any writes.
   9
  10 This would disable the BIOS option to *not* use a dimmer backlight level
  11 scale while on battery, and who knows what else (there are two other
  12 control bits of unknown function).
  13
  14 Bit 5 controls the "reduce backlight levels when on battery" optional
  15 functionality (active low).  Bits 6 and 7 are better left alone as well,
  16 instead of being forced to zero.
  17
  18 Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
  19 Signed-off-by: Len Brown <len.brown@intel.com>
  20 ---
  21  drivers/misc/thinkpad_acpi.c |   64 ++++++++++++++++++++++++++++++++----------
  22  1 files changed, 49 insertions(+), 15 deletions(-)
  23
  24 diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
  25 index 7dc6b73..5e25abc 100644
  26 --- a/drivers/misc/thinkpad_acpi.c
  27 +++ b/drivers/misc/thinkpad_acpi.c
  28 @@ -4295,8 +4295,16 @@ static struct ibm_struct ecdump_driver_data = {
  29
  30  #define TPACPI_BACKLIGHT_DEV_NAME "thinkpad_screen"
  31
  32 +enum {
  33 +       TP_EC_BACKLIGHT = 0x31,
  34 +
  35 +       /* TP_EC_BACKLIGHT bitmasks */
  36 +       TP_EC_BACKLIGHT_LVLMSK = 0x1F,
  37 +       TP_EC_BACKLIGHT_CMDMSK = 0xE0,
  38 +       TP_EC_BACKLIGHT_MAPSW = 0x20,
  39 +};
  40 +
  41  static struct backlight_device *ibm_backlight_device;
  42 -static int brightness_offset = 0x31;
  43  static int brightness_mode;
  44  static unsigned int brightness_enable = 2; /* 2 = auto, 0 = no, 1 = yes */
  45
  46 @@ -4305,16 +4313,24 @@ static struct mutex brightness_mutex;
  47  /*
  48   * ThinkPads can read brightness from two places: EC 0x31, or
  49   * CMOS NVRAM byte 0x5E, bits 0-3.
  50 + *
  51 + * EC 0x31 has the following layout
  52 + *   Bit 7: unknown function
  53 + *   Bit 6: unknown function
  54 + *   Bit 5: Z: honour scale changes, NZ: ignore scale changes
  55 + *   Bit 4: must be set to zero to avoid problems
  56 + *   Bit 3-0: backlight brightness level
  57 + *
  58 + * brightness_get_raw returns status data in the EC 0x31 layout
  59   */
  60 -static int brightness_get(struct backlight_device *bd)
  61 +static int brightness_get_raw(int *status)
  62  {
  63         u8 lec = 0, lcmos = 0, level = 0;
  64
  65         if (brightness_mode & 1) {
  66 -               if (!acpi_ec_read(brightness_offset, &lec))
  67 +               if (!acpi_ec_read(TP_EC_BACKLIGHT, &lec))
  68                         return -EIO;
  69 -               lec &= (tp_features.bright_16levels)? 0x0f : 0x07;
  70 -               level = lec;
  71 +               level = lec & TP_EC_BACKLIGHT_LVLMSK;
  72         };
  73         if (brightness_mode & 2) {
  74                 lcmos = (nvram_read_byte(TP_NVRAM_ADDR_BRIGHTNESS)
  75 @@ -4325,6 +4341,8 @@ static int brightness_get(struct backlight_device *bd)
  76         }
  77
  78         if (brightness_mode == 3) {
  79 +               *status = lec;  /* Prefer EC, CMOS is just a backing store */
  80 +               lec &= TP_EC_BACKLIGHT_LVLMSK;
  81                 if (lec == lcmos)
  82                         tp_warned.bright_cmos_ec_unsync = 0;
  83                 else {
  84 @@ -4338,9 +4356,11 @@ static int brightness_get(struct backlight_device *bd)
  85                         }
  86                         return -EIO;
  87                 }
  88 +       } else {
  89 +               *status = level;
  90         }
  91
  92 -       return level;
  93 +       return 0;
  94  }
  95
  96  /* May return EINTR which can always be mapped to ERESTARTSYS */
  97 @@ -4348,19 +4368,22 @@ static int brightness_set(int value)
  98  {
  99         int cmos_cmd, inc, i, res;
 100         int current_value;
 101 +       int command_bits;
 102
 103 -       if (value > ((tp_features.bright_16levels)? 15 : 7))
 104 +       if (value > ((tp_features.bright_16levels)? 15 : 7) ||
 105 +           value < 0)
 106                 return -EINVAL;
 107
 108         res = mutex_lock_interruptible(&brightness_mutex);
 109         if (res < 0)
 110                 return res;
 111
 112 -       current_value = brightness_get(NULL);
 113 -       if (current_value < 0) {
 114 -               res = current_value;
 115 +       res = brightness_get_raw(&current_value);
 116 +       if (res < 0)
 117                 goto errout;
 118 -       }
 119 +
 120 +       command_bits = current_value & TP_EC_BACKLIGHT_CMDMSK;
 121 +       current_value &= TP_EC_BACKLIGHT_LVLMSK;
 122
 123         cmos_cmd = value > current_value ?
 124                         TP_CMOS_BRIGHTNESS_UP :
 125 @@ -4375,7 +4398,8 @@ static int brightness_set(int value)
 126                         goto errout;
 127                 }
 128                 if ((brightness_mode & 1) &&
 129 -                   !acpi_ec_write(brightness_offset, i + inc)) {
 130 +                   !acpi_ec_write(TP_EC_BACKLIGHT,
 131 +                                  (i + inc) | command_bits)) {
 132                         res = -EIO;
 133                         goto errout;;
 134                 }
 135 @@ -4398,6 +4422,17 @@ static int brightness_update_status(struct backlight_device *bd)
 136                                 bd->props.brightness : 0);
 137  }
 138
 139 +static int brightness_get(struct backlight_device *bd)
 140 +{
 141 +       int status, res;
 142 +
 143 +       res = brightness_get_raw(&status);
 144 +       if (res < 0)
 145 +               return 0; /* FIXME: teach backlight about error handling */
 146 +
 147 +       return status & TP_EC_BACKLIGHT_LVLMSK;
 148 +}
 149 +
 150  static struct backlight_ops ibm_backlight_data = {
 151         .get_brightness = brightness_get,
 152         .update_status  = brightness_update_status,
 153 @@ -4462,8 +4497,7 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 154         if (brightness_mode > 3)
 155                 return -EINVAL;
 156
 157 -       b = brightness_get(NULL);
 158 -       if (b < 0)
 159 +       if (brightness_get_raw(&b) < 0)
 160                 return 1;
 161
 162         if (tp_features.bright_16levels)
 163 @@ -4481,7 +4515,7 @@ static int __init brightness_init(struct ibm_init_struct *iibm)
 164
 165         ibm_backlight_device->props.max_brightness =
 166                                 (tp_features.bright_16levels)? 15 : 7;
 167 -       ibm_backlight_device->props.brightness = b;
 168 +       ibm_backlight_device->props.brightness = b & TP_EC_BACKLIGHT_LVLMSK;
 169         backlight_update_status(ibm_backlight_device);
 170
 171         return 0;
 172 --
 173 1.5.4.4
 174