viafb: don't touch clock state on OLPC XO-1.5
commit012a1211845eab69a5488d59eb87d24cc518c627
authorDaniel Drake <dsd@laptop.org>
Tue, 4 Sep 2012 15:45:32 +0000 (4 11:45 -0400)
committerFlorian Tobias Schandinat <FlorianSchandinat@gmx.de>
Sat, 22 Sep 2012 21:31:01 +0000 (22 21:31 +0000)
treee2ffa1174de8dd91da1dd71bb108096545fb6c72
parente75478bbd79f4d1694522f1dec7a6cb60c90d3b1
viafb: don't touch clock state on OLPC XO-1.5

As detailed in the thread titled "viafb PLL/clock tweaking causes XO-1.5
instability," enabling or disabling the IGA1/IGA2 clocks causes occasional
stability problems during suspend/resume cycles on this platform.

This is rather odd, as the documentation suggests that clocks have two
states (on/off) and the default (stable) configuration is configured to
enable the clock only when it is needed. However, explicitly enabling *or*
disabling the clock triggers this system instability, suggesting that there
is a 3rd state at play here.

Leaving the clock enable/disable registers alone solves this problem.
This fixes spurious reboots during suspend/resume behaviour introduced by
commit b692a63a.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Cc: stable@vger.kernel.org
drivers/video/via/via_clock.c