[PATCH RFC 10/13] drm/msm: initialize LPAC ring

[Konrad Dybcio]

On 7/6/26 1:07 PM, Anna Maniscalco wrote:
> On 7/6/26 10:44 AM, Konrad Dybcio wrote:
>> On 7/5/26 9:13 PM, Anna Maniscalco wrote:
>>> Program all the register needed to start up LPAC and send initialization
>>> sequence.
>>>
>>> Additionally, now that the LPAC ring is live, make the code aware of it.
>>>
>>> Signed-off-by: Anna Maniscalco <anna.maniscalco2000 at gmail.com>
>>> ---
>> I believe some/all of these writes need to be guarded by if (has_lpac),
>> as many GPUs lack these registers and there may be side effects on
>> others
> 
> That's correct yeah. I'm not sure what has_lpac should be though.
> 
> Something we add to catalog? Or checking if it is a gen that has LPAC?

'Generation' is very much an umbrella term that we can't put too
much trust in in the feature department, kgsl defines it in the
catalog, per-GPU. I think that's the right thing to do.

> 
>>
>>
>> [...]
>>
>>>           a6xx_gpu->shadow = msm_gem_kernel_new(gpu->dev,
>>> -                              sizeof(u32) * gpu->nr_rings,
>>> +                              sizeof(u32) * (gpu->nr_rings + !!gpu->lpac_rb),
>> Should we rename nr_rings to something like nr_XXX_rings
>> where XXX is some uarch-generic (i.e. not SQE because we also
>> support pre-a6xx) name for the main number cruncher?
> Qualcom calls it GC so nr_gc_rings perhaps?

I'm not in the right part of Qualcomm to know, I'll let others comment

Konrad