linux-kernel - Re: [PATCH 4/6] drm/msm/adreno: Implement SMEM-based speed bin

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Date: Wed, 10 Apr 2024 22:26:37 +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 4/6] drm/msm/adreno: Implement SMEM-based speed bin

On Wed, Apr 10, 2024 at 01:42:33PM +0200, Konrad Dybcio wrote:
> 
> 
> On 4/6/24 05:23, Dmitry Baryshkov wrote:
> > On Fri, Apr 05, 2024 at 10:41:32AM +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.
> > > 
> > > Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> > > ---
> 
> [...]
> 
> > 
> > > +	}
> > > +
> > > +	ret = qcom_smem_get_product_code(&pcode);
> > > +	if (ret) {
> > > +		dev_err(dev, "Couldn't get product code from SMEM!\n");
> > > +		return ret;
> > > +	}
> > > +
> > > +	/* Don't consider fcode for external feature codes */
> > > +	if (fcode <= SOCINFO_FC_EXT_RESERVE)
> > > +		fcode = SOCINFO_FC_UNKNOWN;
> > > +
> > > +	*speedbin = FIELD_PREP(ADRENO_SKU_ID_PCODE, pcode) |
> > > +		    FIELD_PREP(ADRENO_SKU_ID_FCODE, fcode);
> > 
> > What about just asking the qcom_smem for the 'gpu_bin' and hiding gory
> > details there? It almost feels that handling raw PCODE / FCODE here is
> > too low-level and a subject to change depending on the socinfo format.
> 
> No, the FCODE & PCODE can be interpreted differently across consumers.

That's why I wrote about asking for 'gpu_bin'.

> 
> > 
> > > +
> > > +	return ret;
> > >   }
> > >   int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev,
> > > @@ -1098,9 +1129,9 @@ int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev,
> > >   			devm_pm_opp_set_clkname(dev, "core");
> > >   	}
> > > -	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);
> > 
> > the &= 0xffff should probably go to the adreno_read_speedbin / nvmem
> > case. WDYT?
> 
> Ok, I can keep it, though realistically if this ever does anything
> useful, it likely means the dt is wrong

Yes, but if DT is wrong, we should probably fail in a sensible way. I
just wanted to point out that previously we had this &0xffff, while your
patch silently removes it.

-- 
With best wishes
Dmitry