linux-kernel - Re: [PATCH v5 1/5] drm/msm/adreno: Implement SMEM-based speed bin

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Message-ID: <87607d2c-a4b1-4923-ba9f-9cfc56a0aa38@kernel.org>
Date: Mon, 29 Jul 2024 14:13:16 +0200
From: Konrad Dybcio <konradybcio@...nel.org>
To: Akhil P Oommen <quic_akhilpo@...cinc.com>
Cc: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
 Abhinav Kumar <quic_abhinavk@...cinc.com>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Bjorn Andersson <andersson@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Marijn Suijten <marijn.suijten@...ainline.org>,
 linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 devicetree@...r.kernel.org, Elliot Berman <quic_eberman@...cinc.com>
Subject: Re: [PATCH v5 1/5] drm/msm/adreno: Implement SMEM-based speed bin

On 16.07.2024 1:56 PM, Konrad Dybcio wrote:
> On 15.07.2024 10:04 PM, Akhil P Oommen wrote:
>> On Tue, Jul 09, 2024 at 12:45:29PM +0200, Konrad Dybcio wrote:
>>> On recent (SM8550+) Snapdragon platforms, the GPU speed bin data is
>>> abstracted through SMEM, instead of being directly available in a fuse.
>>>
>>> Add support for SMEM-based speed binning, which includes getting
>>> "feature code" and "product code" from said source and parsing them
>>> to form something that lets us match OPPs against.
>>>
>>> Due to the product code being ignored in the context of Adreno on
>>> production parts (as of SM8650), hardcode it to SOCINFO_PC_UNKNOWN.
>>>
>>> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
>>> ---
> 
> [...]
> 
>>>  
>>> -	if (adreno_read_speedbin(dev, &speedbin) || !speedbin)
>>> +	if (adreno_read_speedbin(adreno_gpu, dev, &speedbin) || !speedbin)
>>>  		speedbin = 0xffff;
>>> -	adreno_gpu->speedbin = (uint16_t) (0xffff & speedbin);
>>> +	adreno_gpu->speedbin = speedbin;
>>
>> There are some chipsets which uses both Speedbin and Socinfo data for
>> SKU detection [1].
> 
> 0_0
> 
> 
>> We don't need to worry about that logic for now. But
>> I am worried about mixing Speedbin and SKU_ID in the UABI with this patch.
>> It will be difficult when we have to expose both to userspace.
>>
>> I think we can use a separate bitfield to expose FCODE/PCODE. Currently,
>> the lower 32 bit is reserved for chipid and 33-48 is reserved for speedbin,
>> so I think we can use the rest of the 16 bits for SKU_ID. And within that
>> 16bits, 12 bits should be sufficient for FCODE and the rest 8 bits
>> reserved for future PCODE.
> 
> Right, sounds reasonable. Hopefully nothing overflows..

+CC Elliot

Would you know whether these sizes ^ are going to be sufficient for
the foreseeable future?

Konrad