linux-kernel - Re: [PATCH v3 3/7] drm/msm: adreno: dynamically generate GMU bw table

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Message-ID: <00941d91-7366-4836-9d3a-7e505528a4e8@oss.qualcomm.com>
Date: Fri, 29 Nov 2024 17:56:09 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Neil Armstrong <neil.armstrong@...aro.org>,
        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>,
        Bjorn Andersson <andersson@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>,
        Akhil P Oommen <quic_akhilpo@...cinc.com>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org
Subject: Re: [PATCH v3 3/7] drm/msm: adreno: dynamically generate GMU bw table

On 28.11.2024 11:25 AM, Neil Armstrong wrote:
> The Adreno GPU Management Unit (GMU) can also scale the ddr
> bandwidth along the frequency and power domain level, but for
> now we statically fill the bw_table with values from the
> downstream driver.
> 
> Only the first entry is used, which is a disable vote, so we
> currently rely on scaling via the linux interconnect paths.
> 
> Let's dynamically generate the bw_table with the vote values
> previously calculated from the OPPs.
> 
> Those entried will then be used by the GMU when passing the

entries

> appropriate bandwidth level while voting for a gpu frequency.
> 
> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>
> ---

[...]

>  drivers/gpu/drm/msm/adreno/a6xx_hfi.c | 39 ++++++++++++++++++++++++++++++++---
>  1 file changed, 36 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_hfi.c b/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> index cb8844ed46b29c4569d05eb7a24f7b27e173190f..fe1946650425b749bad483dad1e630bc8be83abc 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> @@ -621,6 +621,35 @@ static void a740_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
>  	msg->cnoc_cmds_data[1][0] = 0x60000001;
>  }
>  
> +static void a740_generate_bw_table(const struct a6xx_info *info, struct a6xx_gmu *gmu,
> +				   struct a6xx_hfi_msg_bw_table *msg)

This should work for all targets

> +{
> +	unsigned int i, j;
> +
> +	msg->ddr_wait_bitmask = 0x7;

GENMASK; also should be generated based on BCM data dynamically, there's
logic for it in bcm-voter.c : tcs_list_gen()

> +
> +	for (i = 0; i < GMU_MAX_BCMS; i++) {
> +		if (!info->bcms[i].name)
> +			break;
> +		msg->ddr_cmds_addrs[i] = cmd_db_read_addr(info->bcms[i].name);

A7xx share a common list of BCMs, the buswidth may differ per soc and it's
something already stored in ICC drivers

> +	}
> +	msg->ddr_cmds_num = i;
> +
> +	for (i = 0; i < gmu->nr_gpu_bws; ++i)
> +		for (j = 0; j < msg->ddr_cmds_num; j++)
> +			msg->ddr_cmds_data[i][j] = gmu->gpu_ib_votes[i][j];
> +	msg->bw_level_num = gmu->nr_gpu_bws;
> +
> +	/* TODO also generate CNOC commands */

We only do on/off (0/100 units - kbps?), it seems

> +
> +	msg->cnoc_cmds_num = 1;
> +	msg->cnoc_wait_bitmask = 0x1;
> +
> +	msg->cnoc_cmds_addrs[0] = cmd_db_read_addr("CN0");
> +	msg->cnoc_cmds_data[0][0] = 0x40000000;
> +	msg->cnoc_cmds_data[1][0] = 0x60000001;
> +}
> +
>  static void a6xx_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
>  {
>  	/* Send a single "off" entry since the 630 GMU doesn't do bus scaling */
> @@ -664,6 +693,7 @@ static int a6xx_hfi_send_bw_table(struct a6xx_gmu *gmu)
>  	struct a6xx_hfi_msg_bw_table *msg;
>  	struct a6xx_gpu *a6xx_gpu = container_of(gmu, struct a6xx_gpu, gmu);
>  	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
> +	const struct a6xx_info *info = adreno_gpu->info->a6xx;
>  
>  	if (gmu->bw_table)
>  		goto send;
> @@ -690,9 +720,12 @@ static int a6xx_hfi_send_bw_table(struct a6xx_gmu *gmu)
>  		a690_build_bw_table(msg);
>  	else if (adreno_is_a730(adreno_gpu))
>  		a730_build_bw_table(msg);
> -	else if (adreno_is_a740_family(adreno_gpu))
> -		a740_build_bw_table(msg);
> -	else
> +	else if (adreno_is_a740_family(adreno_gpu)) {
> +		if (info->bcms && gmu->nr_gpu_bws > 1)
> +			a740_generate_bw_table(info, gmu, msg);

This if should come before the hardcoded if-else chain, as it
applies to all platforms

Konrad