Re: [PATCH 5/6] drm/msm/a6xx: Fix IRQ storm during msm_recovery test

[Rob Clark]

On Thu, Jun 4, 2026 at 1:10 PM Akhil P Oommen <akhilpo@xxxxxxxxxxxxxxxx> wrote:
>
> From: Jie Zhang <jie.zhang@xxxxxxxxxxxxxxxx>
>
> Once a hang is triggered by the msm_recovery test, the gpu error irq
> remains asserted and triggers an interrupt storm. In the worst case,
> this IRQ storm lands on the CPU core where the hangcheck timer is
> scheduled, blocking it from running. This eventually leads to CPU
> watchdog timeouts.
>
> To fix this, mask the gpu error irqs during msm_recovery test and
> enable them back during the recovery.
>
> Fixes: 5edf2750d998 ("drm/msm: Add debugfs to disable hw err handling")
> Signed-off-by: Jie Zhang <jie.zhang@xxxxxxxxxxxxxxxx>
> Signed-off-by: Akhil P Oommen <akhilpo@xxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/adreno/a5xx_gpu.c | 5 +++++
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 5 ++++-
>  drivers/gpu/drm/msm/adreno/a8xx_gpu.c | 5 ++++-
>  drivers/gpu/drm/msm/msm_gpu.c         | 2 ++
>  4 files changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> index 2c0bbac43c52..f1df2514c613 100644
> --- a/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a5xx_gpu.c
> @@ -1275,6 +1275,11 @@ static irqreturn_t a5xx_irq(struct msm_gpu *gpu)
>                 status & ~A5XX_RBBM_INT_0_MASK_RBBM_AHB_ERROR);
>
>         if (priv->disable_err_irq) {
> +               /* Turn off interrupts to avoid interrupt storm */
> +               gpu_write(gpu, REG_A5XX_RBBM_INT_0_MASK,
> +                              A5XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS |
> +                              A5XX_RBBM_INT_0_MASK_CP_SW);
> +
>                 status &= A5XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS |
>                           A5XX_RBBM_INT_0_MASK_CP_SW;
>         }
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index 8b3bb2fd433b..9a4f9d0e1780 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -1911,8 +1911,11 @@ static irqreturn_t a6xx_irq(struct msm_gpu *gpu)
>
>         gpu_write(gpu, REG_A6XX_RBBM_INT_CLEAR_CMD, status);
>
> -       if (priv->disable_err_irq)
> +       if (priv->disable_err_irq) {
> +               /* Turn off interrupts to avoid interrupt storm */
> +               gpu_write(gpu, REG_A6XX_RBBM_INT_0_MASK, A6XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS);
>                 status &= A6XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS;
> +       }
>
>         if (status & A6XX_RBBM_INT_0_MASK_RBBM_HANG_DETECT)
>                 a6xx_fault_detect_irq(gpu);
> diff --git a/drivers/gpu/drm/msm/adreno/a8xx_gpu.c b/drivers/gpu/drm/msm/adreno/a8xx_gpu.c
> index 9e44fd1ae634..0f6fd35bd587 100644
> --- a/drivers/gpu/drm/msm/adreno/a8xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a8xx_gpu.c
> @@ -1211,8 +1211,11 @@ irqreturn_t a8xx_irq(struct msm_gpu *gpu)
>
>         gpu_write(gpu, REG_A8XX_RBBM_INT_CLEAR_CMD, status);
>
> -       if (priv->disable_err_irq)
> +       if (priv->disable_err_irq) {
> +               /* Turn off interrupts to avoid interrupt storm */
> +               gpu_write(gpu, REG_A8XX_RBBM_INT_0_MASK, A6XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS);
>                 status &= A6XX_RBBM_INT_0_MASK_CP_CACHE_FLUSH_TS;
> +       }
>
>         if (status & A6XX_RBBM_INT_0_MASK_RBBM_HANG_DETECT)
>                 a8xx_fault_detect_irq(gpu);
> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
> index 9ac7740a87f0..48ac51f4119b 100644
> --- a/drivers/gpu/drm/msm/msm_gpu.c
> +++ b/drivers/gpu/drm/msm/msm_gpu.c
> @@ -552,6 +552,8 @@ static void recover_worker(struct kthread_work *work)
>                 msm_update_fence(ring->fctx, fence);
>         }
>
> +       priv->disable_err_irq = false;

Ok, so we rely on recovery to re-enable the error irqs..  that is
probably ok, given the intended purpose of the debugfs file.  And,
well, it is debugfs.  But why do we clear disable_err_irq here?

BR,
-R

> +
>         gpu->funcs->recover(gpu);
>
>         /* retire completed submits, plus the one that hung: */
>
> --
> 2.51.0
>