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

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Message-ID: <321aa524-ab64-458a-b4c0-70294cc5467d@linaro.org>
Date: Thu, 11 Apr 2024 23:35:43 +0200
From: Konrad Dybcio <konrad.dybcio@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...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 4/10/24 21:26, Dmitry Baryshkov wrote:
> 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'.

I'd rather keep the magic GPU LUTs inside the adreno driver, especially
since not all Snapdragons feature Adreno, but all Adrenos are on
Snapdragons (modulo a2xx but I refuse to make design decisions treating
these equally to e.g. a6xx)

> 
>>
>>>
>>>> +
>>>> +	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.

Right, but I don't believe it actually matters.. If that AND ever did
anything, this was a silent failure with garbage data passed in anyway.

If you really insist, I can remove it separately.

Konrad