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

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Message-ID: <8e2ebc97-f455-4f41-81da-af56263e6cf6@linaro.org>
Date: Tue, 16 Jul 2024 13:56:43 +0200
From: Konrad Dybcio <konrad.dybcio@...aro.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
Subject: Re: [PATCH v5 1/5] drm/msm/adreno: Implement SMEM-based speed bin

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..

Konrad