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SubjectRe: [PATCH v3 5/8] drm/msm/a6xx: Ensure CX collapse during gpu recovery
From
On 30/07/2022 12:40, Akhil P Oommen wrote:
> Because there could be transient votes from other drivers/tz/hyp which
> may keep the cx gdsc enabled, we should poll until cx gdsc collapses.
> We can use the reset framework to poll for cx gdsc collapse from gpucc
> clk driver.
>
> This feature requires support from the platform's gpucc driver.
>
> Signed-off-by: Akhil P Oommen <quic_akhilpo@quicinc.com>
> ---
>
> Changes in v3:
> - Use reset interface from gpucc driver to poll for cx gdsc collapse
> https://patchwork.freedesktop.org/series/106860/
>
> drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 4 ++++
> drivers/gpu/drm/msm/msm_gpu.c | 4 ++++
> drivers/gpu/drm/msm/msm_gpu.h | 4 ++++
> 3 files changed, 12 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 1b049c5..721d5e6 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -10,6 +10,7 @@
>
> #include <linux/bitfield.h>
> #include <linux/devfreq.h>
> +#include <linux/reset.h>
> #include <linux/soc/qcom/llcc-qcom.h>
>
> #define GPU_PAS_ID 13
> @@ -1224,6 +1225,9 @@ static void a6xx_recover(struct msm_gpu *gpu)
> /* And the final one from recover worker */
> pm_runtime_put_sync(&gpu->pdev->dev);
>
> + /* Call into gpucc driver to poll for cx gdsc collapse */
> + reset_control_reset(gpu->cx_collapse);

Do we have a race between the last pm_runtime_put_sync(), this polling
and other voters removing their votes beforehand?

> +
> pm_runtime_use_autosuspend(&gpu->pdev->dev);
>
> if (active_submits)
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index 07e55a6..4a57627 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -14,6 +14,7 @@
> #include <generated/utsrelease.h>
> #include <linux/string_helpers.h>
> #include <linux/devcoredump.h>
> +#include <linux/reset.h>
> #include <linux/sched/task.h>
>
> /*
> @@ -903,6 +904,9 @@ int msm_gpu_init(struct drm_device *drm, struct platform_device *pdev,
> if (IS_ERR(gpu->gpu_cx))
> gpu->gpu_cx = NULL;
>
> + gpu->cx_collapse = devm_reset_control_get_optional(&pdev->dev,
> + "cx_collapse");
> +
> gpu->pdev = pdev;
> platform_set_drvdata(pdev, &gpu->adreno_smmu);
>
> diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h
> index 6def008..ab59fd2 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.h
> +++ b/drivers/gpu/drm/msm/msm_gpu.h
> @@ -13,6 +13,7 @@
> #include <linux/interconnect.h>
> #include <linux/pm_opp.h>
> #include <linux/regulator/consumer.h>
> +#include <linux/reset.h>
>
> #include "msm_drv.h"
> #include "msm_fence.h"
> @@ -268,6 +269,9 @@ struct msm_gpu {
> bool hw_apriv;
>
> struct thermal_cooling_device *cooling;
> +
> + /* To poll for cx gdsc collapse during gpu recovery */
> + struct reset_control *cx_collapse;
> };
>
> static inline struct msm_gpu *dev_to_gpu(struct device *dev)


--
With best wishes
Dmitry

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