[Intel-gfx] [PATCH] drm/i915: add psr toggle to debugfs

[Rodrigo Vivi]

I'm not sure that that property will be accepted...
if so it can be changed to toggle, but for now it is informative only
(DRM_MODE_PROP_IMMUTABLE).


On Wed, Apr 15, 2015 at 2:51 PM, Eric Caruso <ejcaruso at chromium.org> wrote:
> On Wed, Apr 15, 2015 at 2:39 PM, Rodrigo Vivi <rodrigo.vivi at gmail.com> wrote:
>> On Fri, Mar 13, 2015 at 1:46 PM, Eric Caruso <ejcaruso at chromium.org> wrote:
>>> On Fri, Mar 13, 2015 at 1:14 PM, Paulo Zanoni <przanoni at gmail.com> wrote:
>>>> 2015-03-13 16:01 GMT-03:00 Daniel Vetter <daniel at ffwll.ch>:
>>>>> On Fri, Mar 13, 2015 at 7:10 PM, Eric Caruso <ejcaruso at chromium.org> wrote:
>>>>>> This patch allows userspace to toggle PSR through a debugfs interface.
>>>>>> It adds functionality to write 0 or 1 to the existing
>>>>>> i915_edp_psr_status file in order to change the relevant module
>>>>>> parameter and enable/disable PSR.
>>>>>>
>>>>>> Previous upstream feedback did not like making it a connector property
>>>>>> or putting it in sysfs because that would require API stability going
>>>>>> forward. debugfs interfaces do not have this restriction.
>>>>>>
>>>>>> Signed-off-by: Eric Caruso <ejcaruso at chromium.org>
>>>>>
>>>>> What do we need this for? debugfs is generally for debugging (where
>>>>> the module option should be enough) and for testcases (which doesn't
>>>>> seem to be the case here).
>>>>
>>>> What is wrong with "echo 1 > /sys/module/i915/parameters/enable_psr"?
>>>>
>>>>> -Daniel
>>>>> --
>>>>> Daniel Vetter
>>>>> Software Engineer, Intel Corporation
>>>>> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
>>>>> _______________________________________________
>>>>> Intel-gfx mailing list
>>>>> Intel-gfx at lists.freedesktop.org
>>>>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>>>
>>>>
>>>>
>>>> --
>>>> Paulo Zanoni
>>>
>>> Forgive me if this is wrong, but updating the module parameter doesn't
>>> change whether or not PSR is enabled immediately. You need to go through
>>> intel_enable_ddi for this to take effect.
>>
>> indeed.
>>
>>>
>>> We were using something like this for testing on Chromium OS, because
>>> PSR would sometimes cause issues. This allows us to change the module
>>> parameter and enable/disable PSR in one step.
>>
>> I like the idea. But I'd prefer a sysfs toggle interface though...
>
> Aren't you adding a connector property at this point? If so, it seems like both
> this debugfs knob and a hypothetical sysfs interface would both be unnecessary.
> (see: http://lists.freedesktop.org/archives/intel-gfx/2015-March/063074.html)
>
>>
>>>
>>> The upstream feedback I mentioned was done about a year ago:
>>> http://lists.freedesktop.org/archives/intel-gfx/2014-March/041896.html
>>> It seemed to favor a debugfs knob for this.
>>> _______________________________________________
>>> Intel-gfx mailing list
>>> Intel-gfx at lists.freedesktop.org
>>> http://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>
>>
>>
>> --
>> Rodrigo Vivi
>> Blog: http://blog.vivi.eng.br



-- 
Rodrigo Vivi
Blog: http://blog.vivi.eng.br