[PATCH] ARM: dts: remove display power domain for exynos5420

Hi Rahul,

On 07.07.2014 15:37, Rahul Sharma wrote:

Hi Andrej, Inki,

On 18 June 2014 12:06, Rahul Sharma [off-list ref] wrote:

quoted

Hi Andrej,

On 18 June 2014 11:46, Andrzej Hajda [off-list ref] wrote:

quoted

On 06/17/2014 07:49 AM, Rahul Sharma wrote:

quoted

Hi All,

Please review this patch.

Regards,
Rahul Sharma

On 9 June 2014 16:58, Rahul Sharma [off-list ref] wrote:

quoted

Display domain is removed due to instability issues. Explaining
the problem below:

exynos_init_late triggers the pm_genpd_poweroff_unused which
powers off the unused power domains. This call hits before
the trigger to deferred probes.

DRM DP Panel defers the probe due to supply get failure. By the
time, deferred probe is scheduled again, Display Power Domain is
powered off by pm_genpd_poweroff_unused.

FIMD and DP drivers are accessing registers during Probe and Bind
callbacks. If display domain is enabled/disabled around register
accesses, display domain gets unstable and we are getting Power
Domain Disable fail notification. Increasing the Timeout also
didn't help.

As I understand the problem is that fimd and dp drivers access hw
registers without enabling power domain. So the proper solution is to
fix these drivers.

That is also a problem but I fixed those accesses in my local kernel before
hitting this issue. If we do register accesses in FIMD/DP probe/bind we
observes "Prefetch abort" exception. But here the problem is that 'DP
domain disable' starts failing if we enable/disable multiple times.

quoted

Btw. there are already patches removing hw access from probe/bind of
fimd. I guess removing also hw access from dp probe/bind could be a good
solution.

Please let me know the links for posted patches. I will test with those patches.

Is there any update on this? Please share the patches which fixes the
above issue or avoid the above scenario of multiple PM Domain enable/disable.
I will test them for exynos5 based boards. Otherwise we should get this change
merged else display will remain broken for exynos5 based boards.

Andrzej is on holidays right now, so he won't be able to reply in this
thread until he's back. Here are two patches I was able to find on the
related MLs that might be fixing the cause of your issues:

[PATCH] drm/exynos: remove hardware overlays disable from fimd probe
(https://www.mail-archive.com/linux-samsung-soc at vger.kernel.org/msg31629.html)

[PATCH] drm/exynos: fimd: Keep power enabled during fimd_bind
(https://lkml.org/lkml/2014/7/4/188)

Best regards,
Tomasz