linux-kernel - Re: [PATCH v2 13/14] drm/msm/a6xx: Add A619

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Message-ID: <5fdb7416-4764-1bae-08b4-31fc2cdd7860@linaro.org>
Date:   Fri, 17 Feb 2023 23:25:10 +0200
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>,
        linux-arm-msm@...r.kernel.org, andersson@...nel.org,
        agross@...nel.org
Cc:     marijn.suijten@...ainline.org, Rob Clark <robdclark@...il.com>,
        Abhinav Kumar <quic_abhinavk@...cinc.com>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>,
        Chia-I Wu <olvaffe@...il.com>,
        Douglas Anderson <dianders@...omium.org>,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 13/14] drm/msm/a6xx: Add A619_holi speedbin support

On 14/02/2023 19:31, Konrad Dybcio wrote:
> A619_holi is implemented on at least two SoCs: SM4350 (holi) and SM6375
> (blair). This is what seems to be a first occurrence of this happening,
> but it's easy to overcome by guarding the SoC-specific fuse values with
> of_machine_is_compatible(). Do just that to enable frequency limiting
> on these SoCs.
> 
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>
> ---
>   drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 31 +++++++++++++++++++++++++++
>   1 file changed, 31 insertions(+)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index ffe0fd431a76..94b4d93619ed 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -2094,6 +2094,34 @@ static u32 a618_get_speed_bin(u32 fuse)
>   	return UINT_MAX;
>   }
>   
> +static u32 a619_holi_get_speed_bin(u32 fuse)
> +{
> +	/*
> +	 * There are (at least) two SoCs implementing A619_holi: SM4350 (holi)
> +	 * and SM6375 (blair). Limit the fuse matching to the corresponding
> +	 * SoC to prevent bogus frequency setting (as improbable as it may be,
> +	 * given unexpected fuse values are.. unexpected! But still possible.)
> +	 */
> +
> +	if (fuse == 0)
> +		return 0;
> +
> +	if (of_machine_is_compatible("qcom,sm4350")) {
> +		if (fuse == 138)
> +			return 1;
> +		else if (fuse == 92)
> +			return 2;
> +	} else if (of_machine_is_compatible("qcom,sm6375")) {
> +		if (fuse == 190)
> +			return 1;
> +		else if (fuse == 177)
> +			return 2;

Ugh.

> +	} else
> +		pr_warn("Unknown SoC implementing A619_holi!\n");
> +
> +	return UINT_MAX;
> +}
> +
>   static u32 a619_get_speed_bin(u32 fuse)
>   {
>   	if (fuse == 0)
> @@ -2153,6 +2181,9 @@ static u32 fuse_to_supp_hw(struct device *dev, struct adreno_rev rev, u32 fuse)
>   	if (adreno_cmp_rev(ADRENO_REV(6, 1, 8, ANY_ID), rev))
>   		val = a618_get_speed_bin(fuse);
>   
> +	else if (adreno_cmp_rev(ADRENO_REV(6, 1, 9, 1), rev))

I really think it begs to have && !of_find_property(dev->of_node, 
"qcom,gmu") here.

> +		val = a619_holi_get_speed_bin(fuse);
> +
>   	else if (adreno_cmp_rev(ADRENO_REV(6, 1, 9, ANY_ID), rev))
>   		val = a619_get_speed_bin(fuse);
>   

-- 
With best wishes
Dmitry