[Intel-gfx] [PATCH] drm/i915: decouple runtime PM enablement from DMC presence

[Tahvanainen, Jari]

" Do we have a bug about this at bugs.freedesktop.org?" I did quick query on fdo.bugzilla and did not find any matching item (afaik) from there (with i915_feature = GPU *hang*|*DMC*) so I would claim that bug is not filed. Stephane can correct my wrong sayings here. 

BR, Jari

-----Original Message-----
From: Jani Nikula [mailto:jani.nikula at linux.intel.com] 
Sent: Friday, August 18, 2017 12:08 PM
To: Stéphane Marchesin <marcheu at chromium.org>
Cc: Deak, Imre <imre.deak at intel.com>; Rodrigo Vivi <rodrigo.vivi at gmail.com>; intel-gfx at lists.freedesktop.org; Matt Atwood <matthew.s.atwood at intel.corp-partner.google.com>; Saarinen, Jani <jani.saarinen at intel.com>; Tahvanainen, Jari <jari.tahvanainen at intel.com>
Subject: Re: [Intel-gfx] [PATCH] drm/i915: decouple runtime PM enablement from DMC presence

On Thu, 17 Aug 2017, Stéphane Marchesin <marcheu at chromium.org> wrote:
> On Mon, Jun 19, 2017 at 11:45 AM, Jani Nikula 
> <jani.nikula at linux.intel.com> wrote:
>>
>> On Thu, 15 Jun 2017, Imre Deak <imre.deak at intel.com> wrote:
>> > On Thu, Jun 15, 2017 at 10:20:57AM -0700, Rodrigo Vivi wrote:
>> >> I believe it is worth allowing RPM to work without requiring DMC, no?!
>> >
>> > Not if there is no good reason for not using DMC. It was decided 
>> > early on that we won't support that configuration since if you care 
>> > about the power saving provided by partially disabling things you 
>> > probably also care about the bigger power saving provided by DMC. 
>> > So that is the current state of the driver, enabling runtime PM 
>> > without having DMC loaded is not supported. Proper support for that 
>> > would need to be added after a justification why not to use the firmware.
>>
>> Agreed. We already have too many configurations to support, and we 
>> already struggle with our testing coverage as-is. Adding new 
>> configurations to be tested is not to be taken lightly.
>>
>
> For context, we are seeing GPU hangs at suspend/resume with DMC 
> enabled (feel free to email me if you want to be added to the internal
> bug) which is the reason for this patch. If those GPU hangs can be 
> fixed instead, then that would be an even better solution, IMO. Is 
> there someone on your side who could help with these hangs?

We need to get the GPU hangs fixed, obviously. Is this reproducible with upstream code? Do we have a bug about this at bugs.freedesktop.org?
Jani, Jari?

BR,
Jani.


>
> Stéphane
>
>>
>> BR,
>> Jani.
>>
>> --
>> Jani Nikula, Intel Open Source Technology Center

--
Jani Nikula, Intel Open Source Technology Center