linux-kernel - Re: [PATCH v2 3/6] drm/msm/a2xx: Implement .gpu

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Date:   Thu, 23 Feb 2023 04:09:19 +0200
From:   Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To:     Konrad Dybcio <konrad.dybcio@...aro.org>
Cc:     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>, linux-arm-msm@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, freedreno@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/6] drm/msm/a2xx: Implement .gpu_busy

On Thu, 23 Feb 2023 at 03:47, Konrad Dybcio <konrad.dybcio@...aro.org> wrote:
>
> Implement gpu_busy based on the downstream msm-3.4 code [1]. This
> allows us to use devfreq on this old old old hardware!
>
> [1] https://github.com/LineageOS/android_kernel_sony_apq8064/blob/lineage-16.0/drivers/gpu/msm/adreno_a2xx.c#L1975
>
> Signed-off-by: Konrad Dybcio <konrad.dybcio@...aro.org>

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>

Small nit below

> ---
>  drivers/gpu/drm/msm/adreno/a2xx_gpu.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a2xx_gpu.c b/drivers/gpu/drm/msm/adreno/a2xx_gpu.c
> index c67089a7ebc1..6f9876b37db5 100644
> --- a/drivers/gpu/drm/msm/adreno/a2xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a2xx_gpu.c
> @@ -481,6 +481,29 @@ a2xx_create_address_space(struct msm_gpu *gpu, struct platform_device *pdev)
>         return aspace;
>  }
>
> +/* While the precise size of this field is unknown, it holds at least these three values.. */
> +static u64 a2xx_gpu_busy(struct msm_gpu *gpu, unsigned long *out_sample_rate)
> +{
> +       u64 busy_cycles;
> +
> +       /* Freeze the counter */
> +       gpu_write(gpu, REG_A2XX_CP_PERFMON_CNTL, PERF_STATE_FREEZE);
> +
> +       busy_cycles = gpu_read64(gpu, REG_A2XX_RBBM_PERFCOUNTER1_LO);
> +
> +       /* Reset the counter */
> +       gpu_write(gpu, REG_A2XX_CP_PERFMON_CNTL, PERF_STATE_RESET);
> +
> +       /* Re-enable the performance monitors */
> +       gpu_rmw(gpu, REG_A2XX_RBBM_PM_OVERRIDE2, BIT(6), BIT(6));

It's DEBUG_PERF_SCLK_PM_OVERRIDE

See https://github.com/genesi/linux-legacy/blob/master/drivers/mxc/amd-gpu/include/reg/yamato/10/yamato_mask.h#L4428

> +       gpu_write(gpu, REG_A2XX_RBBM_PERFCOUNTER1_SELECT, 1);
> +       gpu_write(gpu, REG_A2XX_CP_PERFMON_CNTL, PERF_STATE_ENABLE);
> +
> +       *out_sample_rate = clk_get_rate(gpu->core_clk);
> +
> +       return busy_cycles;
> +}
> +
>  static u32 a2xx_get_rptr(struct msm_gpu *gpu, struct msm_ringbuffer *ring)
>  {
>         ring->memptrs->rptr = gpu_read(gpu, REG_AXXX_CP_RB_RPTR);
> @@ -502,6 +525,7 @@ static const struct adreno_gpu_funcs funcs = {
>  #if defined(CONFIG_DEBUG_FS) || defined(CONFIG_DEV_COREDUMP)
>                 .show = adreno_show,
>  #endif
> +               .gpu_busy = a2xx_gpu_busy,
>                 .gpu_state_get = a2xx_gpu_state_get,
>                 .gpu_state_put = adreno_gpu_state_put,
>                 .create_address_space = a2xx_create_address_space,
>
> --
> 2.39.2
>


-- 
With best wishes
Dmitry