Re: [PATCH 1/2] dt-bindings: display/msm/gpu: Narrow reg and reg-names for Adreno 610.0 and alike

[Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>]

On 12/29/25 8:23 AM, Krzysztof Kozlowski wrote:
> On 28/12/2025 15:59, Rob Clark wrote:
>> On Sat, Dec 27, 2025 at 11:56 PM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>>>
>>> On 27/12/2025 23:01, Rob Clark wrote:
>>>> On Sat, Dec 27, 2025 at 3:05 AM Krzysztof Kozlowski
>>>> <krzysztof.kozlowski@oss.qualcomm.com> wrote:
>>>>>
>>>>> DTS files for qcom,adreno-610.0 and qcom,adreno-07000200 contain only one
>>>>> "reg" entry, not two, and the binding defines the second entry in
>>>>> "reg-names" differently than top-level part, so just simplify it and
>>>>> narrow to only one entry.
>>>>
>>>> I'll defer to Akhil about whether this is actually needed (vs just
>>>> incomplete gpu devcoredump support for certain GPUs).  In general
>>>> cx_dbgc is needed to capture state for gpu devcoredump state
>>>> snapshots, but not directly used in normal operations.  It seems
>>>> similar to the situation with mapping gpucc as part of gmu, ie. not
>>>> something the CPU normally deals with directly, but necessary to
>>>> capture crash state.
>>>
>>> I don't get why binding was added with cx_dbgc, but DTS not. Neither
>>> binding nor DTS depends on actual usage, so I assume someone
>>> intentionally did not want DTS to contain cx_dbgc and binding should
>>> follow. Otherwise we should make the DTS complete and make the binding
>>> strict (leading to warnings if DTS is not updated).
>>
>> I'm not sure about the history.. but I can say that cx_dbgc is only
>> used for gpu state snapshot / devcoredump.  So it would be easy to not
>> notice if it were missing.
>>
>> We have a similar slightly ugly thing where gpucc is included in the
>> gmu map.. only for devcoredump.  Maybe we need a different way to
>> handle these things that are only mapped for state capture?
> 
> No. Either hardware has it or not. If hardware has it, then both DTS and
> binding should have it. If people decided that DTS should not have it
> (for whatever reason), then apparently that's the desired hardware
> description and let's remove it from the binding to match the ABI.

I don't recall why it was never added. It's

<0x0 0x05961000 0x0 0x800>

for both 6115 and 2290 though. I'll send a patch to fix that up.
It seems like (at a glance) that there shouldn't be much of an issue
with the crashdumper, but I'm not super sure either..

Konrad