[coreboot] Patch merged into coreboot/master: 4412bc4 OT200: reset MFGTP7 (backlight pwm)
gerrit at coreboot.org
gerrit at coreboot.org
Thu Mar 14 16:32:46 CET 2013
the following patch was just integrated into master:
Author: Christian Gmeiner <christian.gmeiner at gmail.com>
Date: Tue Mar 12 11:07:07 2013 +0100
OT200: reset MFGTP7 (backlight pwm)
The CS5536 companion device has three different power domains.
* working domain
* standby domain
* RTC domain
When the system is "off" only the standby domain is powered.
MFGPT[7:6] are member of the standby power domain.
MFGPT7 is used to control the backlight of the device and so the
timer gets used and configured during system boot. If the system
does a reboot the timer stays configured and the Linux driver
can not use it:
"ot200-backlight: ot200-backlight.0: MFGPT 7 not availale"
The cs5535-mfgpt has a function to hard-reset all MFGPTs but the
system hangs after the first access to a MFGPT register - cause
* This is a sledgehammer that resets all MFGPT timers. This is required by
* some broken BIOSes which leave the system in an unstable state
* (TinyBIOS 0.98, for example; fixed in 0.99). It's uncertain as to
* whether or not this secret MSR can be used to release individual timers.
* Jordan tells me that he and Mitch once played w/ it, but it's unclear
* what the results of that were (and they experienced some instability).
static void reset_all_timers(void)
uint32_t val, dummy;
/* The following undocumented bit resets the MFGPT timers */
val = 0xFF; dummy = 0;
wrmsr(MSR_MFGPT_SETUP, val, dummy);
After playing around with this undocumented MSR it looks like I only
need to set bit 7 to free the MFGPT7.
BTW, all MFGPT[0:5] will be reset during pll_reset().
Signed-off-by: Christian Gmeiner <christian.gmeiner at gmail.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Jens Rottmann <JRottmann at LiPPERTembedded.de>
Reviewed-by: Paul Menzel <paulepanter at users.sourceforge.net>
Reviewed-by: Marc Jones <marc.jones at se-eng.com>
Build-Tested: build bot (Jenkins) at Tue Mar 12 10:56:37 2013, giving +1
Reviewed-By: Marc Jones <marc.jones at se-eng.com> at Thu Mar 14 16:32:45 2013, giving +2
See http://review.coreboot.org/2527 for details.
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