linux-kernel - Re: [PATCH v4 3/7] drm/msm: adreno: dynamically generate GMU bw table

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Message-ID: <93ed4511-55b5-42a9-a3fe-32f29bd01bab@quicinc.com>
Date: Mon, 9 Dec 2024 17:41:24 +0530
From: Akhil P Oommen <quic_akhilpo@...cinc.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>
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 v4 3/7] drm/msm: adreno: dynamically generate GMU bw table

On 12/5/2024 8:31 PM, 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 entries will then be used by the GMU when passing the
> 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 | 41 ++++++++++++++++++++++++++++++++++-
>  1 file changed, 40 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_hfi.c b/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> index cb8844ed46b29c4569d05eb7a24f7b27e173190f..fc4bfad51de9a3b6617fbbd03471a5851d43ce88 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> @@ -5,7 +5,10 @@
>  #include <linux/circ_buf.h>
>  #include <linux/list.h>
>  
> +#include <dt-bindings/interconnect/qcom,icc.h>
> +
>  #include <soc/qcom/cmd-db.h>
> +#include <soc/qcom/tcs.h>
>  
>  #include "a6xx_gmu.h"
>  #include "a6xx_gmu.xml.h"
> @@ -259,6 +262,39 @@ static int a6xx_hfi_send_perf_table(struct a6xx_gmu *gmu)
>  		NULL, 0);
>  }
>  
> +static void a6xx_generate_bw_table(const struct a6xx_info *info, struct a6xx_gmu *gmu,
> +				   struct a6xx_hfi_msg_bw_table *msg)
> +{
> +	unsigned int i, j;
> +
> +	msg->ddr_wait_bitmask = QCOM_ICC_TAG_ALWAYS;

Why this is QCOM_ICC_TAG_ALWAYS?

IIRC, this bitmask informs RPMH whether it should wait for previous BCM
vote to complete. Can we implement the same logic from kgsl to create
this bitmask?


> +
> +	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);
> +	}
> +	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;
> +
> +	/*
> +	 * These are the CX (CNOC) votes - these are used by the GMU
> +	 * The 'CN0' BCM is used on all targets, and votes are basically
> +	 * 'off' and 'on' states with first bit to enable the path.
> +	 */
> +
> +	msg->cnoc_cmds_num = 1;
> +	msg->cnoc_wait_bitmask = QCOM_ICC_TAG_AMC;

Same here.

Rest looks fine to me.

-Akhil

> +
> +	msg->cnoc_cmds_addrs[0] = cmd_db_read_addr("CN0");
> +	msg->cnoc_cmds_data[0][0] = BCM_TCS_CMD(true, false, 0, 0);
> +	msg->cnoc_cmds_data[1][0] = BCM_TCS_CMD(true, true, 0, BIT(0));
> +}
> +
>  static void a618_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
>  {
>  	/* Send a single "off" entry since the 618 GMU doesn't do bus scaling */
> @@ -664,6 +700,7 @@ 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;
> @@ -672,7 +709,9 @@ static int a6xx_hfi_send_bw_table(struct a6xx_gmu *gmu)
>  	if (!msg)
>  		return -ENOMEM;
>  
> -	if (adreno_is_a618(adreno_gpu))
> +	if (info->bcms && gmu->nr_gpu_bws > 1)
> +		a6xx_generate_bw_table(info, gmu, msg);
> +	else if (adreno_is_a618(adreno_gpu))
>  		a618_build_bw_table(msg);
>  	else if (adreno_is_a619(adreno_gpu))
>  		a619_build_bw_table(msg);
>