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

[Eric Caruso]

On Thu, Apr 16, 2015 at 8:58 AM, Rodrigo Vivi <rodrigo.vivi at gmail.com> wrote:
> 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).
>

Okay, that changes things somewhat. There'll have to be some discussion over
what the sysfs interface would be, then. It's supposed to be stable, if I
understand correctly.

>
> 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