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SubjectRe: [PATCH v2 06/14] drm/msm/gpu: Use dev_pm_opp_set_rate for non-GMU GPUs
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On 14/02/2023 19:31, Konrad Dybcio wrote:
> Currently we only utilize the OPP table connected to the GPU for
> getting (available) frequencies. We do however need to scale the
> voltage rail(s) accordingly to ensure that we aren't trying to
> run the GPU at 1GHz with a VDD_LOW vote, as that would result in
> an otherwise inexplainable hang.
>
> Tell the OPP framework that we want to scale the "core" clock
> and swap out the clk_set_rate to a dev_pm_opp_set_rate in
> msm_devfreq_target() to enable usage of required-opps and by
> extension proper voltage level/corner scaling.
>
> Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
> ---
> drivers/gpu/drm/msm/adreno/adreno_gpu.c | 4 ++++
> drivers/gpu/drm/msm/msm_gpu_devfreq.c | 2 +-
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index ce6b76c45b6f..15e405e4f977 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -1047,6 +1047,10 @@ int adreno_gpu_init(struct drm_device *drm, struct platform_device *pdev,
> const char *gpu_name;
> u32 speedbin;
>
> + /* This can only be done here, or devm_pm_opp_set_supported_hw will WARN_ON() */
> + if (!IS_ERR(devm_clk_get(dev, "core")))
> + devm_pm_opp_set_clkname(dev, "core");

Can we instead move a call to a6xx_set_supported_hw() / check_speed_bin
after the adreno_gpu_init() ? It will call msm_gpu_init, which in turn
sets gpu->core_clk.

Ideally you can call devm_pm_opp_set_clkname() from that function. Or
maybe completely drop gpu->core_clk and always use
devm_pm_opp_set_clk_rate().

> +
> adreno_gpu->funcs = funcs;
> adreno_gpu->info = adreno_info(config->rev);
> adreno_gpu->gmem = adreno_gpu->info->gmem;
> diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> index e27dbf12b5e8..ea70c1c32d94 100644
> --- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> +++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
> @@ -48,7 +48,7 @@ static int msm_devfreq_target(struct device *dev, unsigned long *freq,
> gpu->funcs->gpu_set_freq(gpu, opp, df->suspended);
> mutex_unlock(&df->lock);
> } else {
> - clk_set_rate(gpu->core_clk, *freq);
> + dev_pm_opp_set_rate(dev, *freq);

This is not enough, there are calls to clk_set_rate(gpu->core_clk) in
msm_gpu.c which are called from the suspend/resume path.

> }
>
> dev_pm_opp_put(opp);

--
With best wishes
Dmitry

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