[Intel-gfx] [PATCH] drm/i915: Allow control of PSR at runtime through debugfs.

[Maarten Lankhorst]

Op 14-03-18 om 17:07 schreef Chris Wilson:
> Quoting Maarten Lankhorst (2018-03-14 15:58:32)
>> Currently tests modify i915.enable_psr and then do a modeset cycle
>> to change PSR. We can write a value to i915_edp_psr_status to force
>> a certain value without a modeset.
>>
>> To retain compatibility with older userspace, we also still allow
>> the override through the module parameter, and add some tracking
>> to check whether a debugfs mode is specified.
> Is it possible for you to mandate that the process holds the file open
> for as long as it wants its value to hold. Then we can automatically
> clean up if the process dies; without requiring userspace to dig itself
> out of a hole.
> -Chris

For testing PSR someone might directly echo values to the debugfs file, so I didn't want to keep the fd handle as reference count..