linux-kernel - Re: [PATCH v4 1/5] drm/msm/adreno: Implement SMEM-based speed bin

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Message-ID: <5a622896-6ce3-4e73-9383-15793b2536bc@linaro.org>
Date: Tue, 9 Jul 2024 12:25:50 +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 v4 1/5] drm/msm/adreno: Implement SMEM-based speed bin

On 30.06.2024 12:25 PM, Akhil P Oommen wrote:
> On Tue, Jun 25, 2024 at 08:28:06PM +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>
>> ---

[...]

> 
> This value is exposed to userspace via MSM_PARAM_CHIP_ID. 16 bits are
> reserved for speedbin, so we should ensure somewhere that we don't
> accidently use more than that.

The "real" chip id is 32b, leaving the other 32 for speedbin, so it's fine

> 
> Also, what is the the max value of fcode? I think we should leave some
> space for pcode too. We never know for sure if that won't be required in
> future.

As of today it seems to be 0xff. Worst case scenario we'll add a new param,
but hopefully the people that are in charge won't randomly change things..

Konrad