linux-kernel - Re: [PATCH RFC 1/3] drm/msm/adreno: Add support for ACD

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Message-ID: <4aeec9f1-720b-400c-9582-d02847db2ac7@linaro.org>
Date: Mon, 4 Nov 2024 16:44:56 +0100
From: neil.armstrong@...aro.org
To: Akhil P Oommen <quic_akhilpo@...cinc.com>, Rob Clark
 <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
 Konrad Dybcio <konradybcio@...nel.org>,
 Abhinav Kumar <quic_abhinavk@...cinc.com>,
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
 Marijn Suijten <marijn.suijten@...ainline.org>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
 Stephen Boyd <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Bjorn Andersson <andersson@...nel.org>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
 linux-pm@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH RFC 1/3] drm/msm/adreno: Add support for ACD

On 11/10/2024 22:29, Akhil P Oommen wrote:
> ACD a.k.a Adaptive Clock Distribution is a feature which helps to reduce
> the power consumption. In some chipsets, it is also a requirement to
> support higher GPU frequencies. This patch adds support for GPU ACD by
> sending necessary data to GMU and AOSS. The feature support for the
> chipset is detected based on devicetree data.
> 
> Signed-off-by: Akhil P Oommen <quic_akhilpo@...cinc.com>
> ---
>   drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 81 ++++++++++++++++++++++++++++-------
>   drivers/gpu/drm/msm/adreno/a6xx_gmu.h |  1 +
>   drivers/gpu/drm/msm/adreno/a6xx_hfi.c | 36 ++++++++++++++++
>   drivers/gpu/drm/msm/adreno/a6xx_hfi.h | 21 +++++++++
>   4 files changed, 124 insertions(+), 15 deletions(-)
> 

<snip>

> +
> +static int a6xx_hfi_enable_acd(struct a6xx_gmu *gmu)
> +{
> +	struct a6xx_hfi_acd_table *acd_table = &gmu->acd_table;
> +	struct a6xx_hfi_msg_feature_ctrl msg = {
> +		.feature = HFI_FEATURE_ACD,
> +		.enable = 1,
> +		.data = 0,
> +	};
> +	int ret;
> +
> +	if (!acd_table->enable_by_level)
> +		return 0;
> +
> +	/* Enable ACD feature at GMU */
> +	ret = a6xx_hfi_send_msg(gmu, HFI_H2F_FEATURE_CTRL, &msg, sizeof(msg), NULL, 0);
> +	if (ret) {
> +		DRM_DEV_ERROR(gmu->dev, "Unable to enable ACD (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	/* Send ACD table to GMU */
> +	ret = a6xx_hfi_send_msg(gmu, HFI_H2F_MSG_ACD, &msg, sizeof(msg), NULL, 0);

This looks wrong, in this exact code, you never use the acd_table... perhaps it should be acd_table here

> +	if (ret) {
> +		DRM_DEV_ERROR(gmu->dev, "Unable to ACD table (%d)\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
>   static int a6xx_hfi_send_test(struct a6xx_gmu *gmu)
>   {
>   	struct a6xx_hfi_msg_test msg = { 0 };
> @@ -756,6 +788,10 @@ int a6xx_hfi_start(struct a6xx_gmu *gmu, int boot_state)
>   	if (ret)
>   		return ret;
>   
> +	ret = a6xx_hfi_enable_acd(gmu);
> +	if (ret)
> +		return ret;
> +
>   	ret = a6xx_hfi_send_core_fw_start(gmu);
>   	if (ret)
>   		return ret;
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_hfi.h b/drivers/gpu/drm/msm/adreno/a6xx_hfi.h
> index 528110169398..51864c8ad0e6 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_hfi.h
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_hfi.h
> @@ -151,12 +151,33 @@ struct a6xx_hfi_msg_test {
>   	u32 header;
>   };
>   
> +#define HFI_H2F_MSG_ACD 7
> +#define MAX_ACD_STRIDE 2
> +
> +struct a6xx_hfi_acd_table {
> +	u32 header;
> +	u32 version;
> +	u32 enable_by_level;
> +	u32 stride;
> +	u32 num_levels;
> +	u32 data[16 * MAX_ACD_STRIDE];
> +};
> +
>   #define HFI_H2F_MSG_START 10
>   
>   struct a6xx_hfi_msg_start {
>   	u32 header;
>   };
>   
> +#define HFI_H2F_FEATURE_CTRL 11
> +
> +struct a6xx_hfi_msg_feature_ctrl {
> +	u32 header;
> +	u32 feature;
> +	u32 enable;
> +	u32 data;
> +};
> +
>   #define HFI_H2F_MSG_CORE_FW_START 14
>   
>   struct a6xx_hfi_msg_core_fw_start {
> 

Thanks,
Neil