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

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Date: Thu, 18 Apr 2024 14:48:13 +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, 18 Apr 2024 at 14:31, Konrad Dybcio <konrad.dybcio@...aro.org> wrote:
>
> On 18.04.2024 1:07 PM, Dmitry Baryshkov wrote:
> > 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?
>
> I don't think that's right. The SoC "product code" may actually mean something
> (again, not necessarily for Adreno specifically), and with Adreno in mind, it
> being only meaningful for engineering samples may change in the future.

Ack


-- 
With best wishes
Dmitry