linux-kernel - Re: [PATCH 3/5] drm: msm: add support for A750 GPU

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Date: Mon, 12 Feb 2024 11:46:15 +0100
From: Konrad Dybcio <konrad.dybcio@...aro.org>
To: Neil Armstrong <neil.armstrong@...aro.org>,
 Rob Clark <robdclark@...il.com>, Abhinav Kumar <quic_abhinavk@...cinc.com>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, Sean Paul <sean@...rly.run>,
 Marijn Suijten <marijn.suijten@...ainline.org>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Conor Dooley <conor+dt@...nel.org>, Will Deacon <will@...nel.org>,
 Robin Murphy <robin.murphy@....com>, Joerg Roedel <joro@...tes.org>,
 Bjorn Andersson <andersson@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 iommu@...ts.linux.dev
Subject: Re: [PATCH 3/5] drm: msm: add support for A750 GPU

On 12.02.2024 11:37, Neil Armstrong wrote:
> Add support for the A750 GPU found on the SM8650 platform
> 
> Unlike the the very close A740 GPU on the SM8550 SoC, the A750 GPU
> doesn't have an HWCFG block but a separate register set.
> 
> The missing registers are added in the a6xx.xml.h file that would
> require a subsequent sync and the non-existent hwcfg is handled
> in a6xx_set_hwcg().

These should also be submitted to mesa to make sure the next header sync
doesn't wipe them

[...]

> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -958,10 +958,11 @@ static void a6xx_set_hwcg(struct msm_gpu *gpu, bool state)
>  	struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
>  	struct a6xx_gmu *gmu = &a6xx_gpu->gmu;
>  	const struct adreno_reglist *reg;
> +	bool skip_programming = !(adreno_gpu->info->hwcg || adreno_is_a7xx(adreno_gpu));

is_a750?

>  	unsigned int i;
>  	u32 val, clock_cntl_on, cgc_mode;
>  
> -	if (!adreno_gpu->info->hwcg)
> +	if (skip_programming)
>  		return;
>  
>  	if (adreno_is_a630(adreno_gpu))
> @@ -982,6 +983,25 @@ static void a6xx_set_hwcg(struct msm_gpu *gpu, bool state)
>  			  state ? 0x5555 : 0);
>  	}
>  
> +	if (!adreno_gpu->info->hwcg) {

I don't think this block of code is reachable now, no?

Maybe remove the skip_programming and if_a750 here?

> +		gpu_write(gpu, REG_A7XX_RBBM_CLOCK_CNTL_GLOBAL, 1);
> +		gpu_write(gpu, REG_A7XX_RBBM_CGC_GLOBAL_LOAD_CMD, state ? 1 : 0);
> +
> +		if (state) {
> +			gpu_write(gpu, REG_A7XX_RBBM_CGC_P2S_TRIG_CMD, 1);
> +
> +			if (gpu_poll_timeout(gpu, REG_A7XX_RBBM_CGC_P2S_STATUS, val,
> +					     val & BIT(0), 1, 10)) {

We should define that bit name (the err suggests it's
REG_A7XX_RBBM_GCC_P2S_STATUS_TXDONE or so)

[...]

> +static inline int adreno_is_a750(struct adreno_gpu *gpu)
> +{
> +	return gpu->info->chip_ids[0] == 0x43051401;
> +}
> +
>  /* Placeholder to make future diffs smaller */

Please also remove this comment now that it's invalid

Konrad