[PATCH 08/22] drm/tegra: dc: Drop the reset asserts to workaround a bug

Dmitry Osipenko digetx at gmail.com
Tue Jun 13 14:18:37 UTC 2017


On 13.06.2017 16:45, Thierry Reding wrote:
> On Tue, May 23, 2017 at 03:14:23AM +0300, Dmitry Osipenko wrote:
>> Commit 33a8eb8 ("Implement runtime PM") introduced HW reset control. It
>> causes a hang on Tegra20 if both display controllers are utilized (RGB
>> panel and HDMI). The TRM suggests that each display controller has its own
>> reset control, apparently it is not correct. Let's remove the interaction
>> with the resets for now as a workaround.
>>
>> Fixes: 33a8eb8d40ee ("drm/tegra: dc: Implement runtime PM")
>> Signed-off-by: Dmitry Osipenko <digetx at gmail.com>
>> ---
>>  drivers/gpu/drm/tegra/dc.c | 15 ---------------
>>  1 file changed, 15 deletions(-)
> 
> Do you mind if I parameterize this to restrict omission of the assert
> and deassert to Tegra20? I'm fairly sure that these resets are important
> on later chips in order to properly reset the display controllers.

I don't mind at all, I can parameterize it in the next rev myself if you wish.

> My proposal would be to add a field to struct tegra_dc_soc_info (maybe
> .broken_reset) that will be set only on Tegra20 to still allow the DC to
> be reset on later generations.

Sounds good.

-- 
Dmitry


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