[Intel-gfx] [PATCH] drm/i915/psr: Split sel fetch plane configuration into arm and noarm

[Tvrtko Ursulin]

On 26/01/2023 16:05, Jani Nikula wrote:
> On Thu, 26 Jan 2023, Luca Coelho <luca at coelho.fi> wrote:
>> On Thu, 2023-01-26 at 14:11 +0200, Luca Coelho wrote:
>>> On Thu, 2023-01-26 at 14:00 +0200, Jani Nikula wrote:
>>>> On Thu, 26 Jan 2023, Luca Coelho <luca at coelho.fi> wrote:
>>>>> On Wed, 2023-01-25 at 12:44 +0200, Jouni Högander wrote:
>>>>>>> diff --git a/drivers/gpu/drm/i915/display/intel_psr.c b/drivers/gpu/drm/i915/display/intel_psr.c
>>>>>>> index 7d4a15a283a0..63b79c611932 100644
>>>>>>> --- a/drivers/gpu/drm/i915/display/intel_psr.c
>>>>>>> +++ b/drivers/gpu/drm/i915/display/intel_psr.c
>>>>>>> @@ -1559,7 +1559,26 @@ void intel_psr2_disable_plane_sel_fetch(struct intel_plane *plane,
>>>>>>>   	intel_de_write_fw(dev_priv, PLANE_SEL_FETCH_CTL(pipe, plane->id), 0);
>>>>>>>   }
>>>>>>>   
>>>>>>> -void intel_psr2_program_plane_sel_fetch(struct intel_plane *plane,
>>>>>>> +void intel_psr2_program_plane_sel_fetch_arm(struct intel_plane *plane,
>>>>>>> +					const struct intel_crtc_state *crtc_state,
>>>>>>> +					const struct intel_plane_state *plane_state,
>>>>>>> +					int color_plane)
>>>>>>> +{
>>>>>>> +	struct drm_i915_private *dev_priv = to_i915(plane->base.dev);
>>>>>
>>>>> Should you use i915 instead of dev_priv? I've heard and read elsewhere
>>>>> that this is generally a desired change.  Much easier to use always the
>>>>> same local name for this kind of thing.  Though this file is already
>>>>> interspersed with both versions...
>>>>
>>>> Basically the only reason to use dev_priv for new code is to deal with
>>>> some register macros that still have implicit dev_priv in
>>>> them. Otherwise, i915 should be used, and when convenient, dev_priv
>>>> should be converted to i915 while touching the code anyway (in a
>>>> separate patch, but while you're there).
>>>
>>> Thanks for the clarification! In this case we're not using any of the
>>> macros, AFAICT, so I guess it's better to go with i915 already? And I
>>> think it should even be in this same patch, since it's a new function
>>> anyway.
>>>
>>>
>>>> The implicit dev_priv dependencies in the register macros are a bit
>>>> annoying to fix, and it's been going slow. In retrospect maybe the right
>>>> thing would have been to just sed the parameter to all of them
>>>> everywhere and be done with it for good. Not too late now, I guess, and
>>>> I'd take the patches in a heartbeat if someone were to step up and do
>>>> it.
>>>
>>> I see that there is a boatload of register macros using it... I won't
>>> promise, but I think it would be a good exercise for a n00b like me to
>>> make this patch, though I already foresee another boatload of conflicts
>>> with the internal trees and everything...
>>
>> There were actually 10 boatloads of places to change:
>>
>>   187 files changed, 12104 insertions(+), 12104 deletions(-)
>>
>> ...but it _does_ compile. 😄
>>
>> Do you think this is fine? Lots of shuffle, but if you think it's okay,
>> I can send the patch out now.
> 
> Heh, I said I'd take patchES, not everything together! ;)
> 
> Rodrigo, Tvrtko, Joonas, thoughts?

IMO if the elimination of implicit dev_priv is not included then I am 
not sure the churn is worth the effort.

I think one trap is that it is easy to assume solving those conflicts is 
easy because there is a script, somewhere, whatever, but one needs to be 
careful with assuming a random person hitting a merge conflict will 
realize there is a script, know where to find it, and know how to use it 
against a state where conflict markers are sitting in their local tree. 
That's a lot of assumed knowledge which my experience tells me is not 
universally there.

Having said all that, I looked at the occurrence histogram for the 
proposed churn and gut feel says conflicts wouldn't even be that bad 
since they seem heavily localized in a handful of files plus the display 
subdir.

Plus it is upstream.. so we are allowed not to care too much about 
backporting woes. I would still hope implicit dev_priv, albeit 
orthogonal, would be coming somewhat together with the rename. For that 
warm fuzzy feeling that the churn was really really worth it.

Regards,

Tvrtko