linux-kernel - Re: [PATCH v2 3/7] drm/msm/adreno: Implement SMEM-based speed bin

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Message-ID: <7ynodjzjuxwwqkjgns5jtnkckw52qyldfpsqpjh7645swva4xk@7wucftyjyyy3>
Date: Thu, 18 Apr 2024 14:07:30 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Konrad Dybcio <konrad.dybcio@...aro.org>
Cc: Bjorn Andersson <andersson@...nel.org>, 
	Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>, 
	Sean Paul <sean@...rly.run>, Marijn Suijten <marijn.suijten@...ainline.org>, 
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org, 
	Neil Armstrong <neil.armstrong@...aro.org>
Subject: Re: [PATCH v2 3/7] drm/msm/adreno: Implement SMEM-based speed bin

On Thu, Apr 18, 2024 at 11:51:16AM +0200, Konrad Dybcio wrote:
> On 18.04.2024 1:43 AM, Dmitry Baryshkov wrote:
> > On Wed, Apr 17, 2024 at 10:02:55PM +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>
> >> ---
> 
> [...]
> 
> >> --- a/drivers/gpu/drm/msm/adreno/adreno_device.c
> >> +++ b/drivers/gpu/drm/msm/adreno/adreno_device.c
> >> @@ -6,6 +6,8 @@
> >>   * Copyright (c) 2014,2017 The Linux Foundation. All rights reserved.
> >>   */
> >>  
> >> +#include <linux/soc/qcom/socinfo.h>
> >> +
> > 
> > Stray leftover?
> 
> Looks like
> 
> [...]
> 
> >> +
> >> +#ifdef CONFIG_QCOM_SMEM
> > 
> > Please extract to a separate function and put the function under ifdef
> > (providing a stub otherwise). Having #ifndefs inside funciton body is
> > frowned upon.
> 
> Hm, this looked quite sparse and straightforward, but I can do that.
> 
> [...]
> 
> >> +/* As of SM8650, PCODE on production SoCs is meaningless wrt the GPU bin */
> >> +#define ADRENO_SKU_ID_FCODE		GENMASK(15, 0)
> >> +#define ADRENO_SKU_ID(fcode)	(SOCINFO_PC_UNKNOWN << 16 | fcode)
> > 
> > If we got rid of PCode matching, is there a need to actually use
> > SOCINFO_PC_UNKNOWN here? Or just 0 would be fine?
> 
> The IDs need to stay constant for mesa
> 
> I used the define here to:
> 
> a) define the SKU_ID structure so that it's clear what it's comprised of
> b) make it easy to add back Pcode in case it becomes useful with future SoCs
> c) avoid mistakes - PC_UNKNOWN happens to be zero, but that's a lucky
>    coincidence
> 
> We don't *match* based on PCODE, but still need to construct the ID properly
> 
> Another option would be to pass the real pcode and add some sort of
> "pcode_invalid" property that if found would ignore this part of the
> SKU_ID in mesa, but that sounds overly and unnecessarily complex.

It's fine, just add a comment please. Maybe we can rename PC_UNKNOWN to
PC_PRODUCTION?

> 
> Konrad
> 
> Konrad

-- 
With best wishes
Dmitry