Re: [PATCH] drm/imagination: Fix deadlock in soft reset sequence

[Matt Coster <Matt.Coster@imgtec.com>]

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On 09/03/2026 15:23, Alessio Belle wrote:
> The soft reset sequence is currently executed from the threaded IRQ
> handler, hence it cannot call disable_irq() which internally waits
> for IRQ handlers, i.e. itself, to complete.
> 
> Use disable_irq_nosync() during a soft reset instead.
> 
> Fixes: cc1aeedb98ad ("drm/imagination: Implement firmware infrastructure and META FW support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Alessio Belle <alessio.belle@imgtec.com>

Reviewed-by: Matt Coster <matt.coster@imgtec.com>

I'll apply to drm-misc-fixes tomorrow.

> ---
>  drivers/gpu/drm/imagination/pvr_power.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/imagination/pvr_power.c b/drivers/gpu/drm/imagination/pvr_power.c
> index 7a8765c0c1ed..046cce76498a 100644
> --- a/drivers/gpu/drm/imagination/pvr_power.c
> +++ b/drivers/gpu/drm/imagination/pvr_power.c
> @@ -510,7 +510,16 @@ pvr_power_reset(struct pvr_device *pvr_dev, bool hard_reset)
>         }
> 
>         /* Disable IRQs for the duration of the reset. */
> -       disable_irq(pvr_dev->irq);
> +       if (hard_reset) {
> +               disable_irq(pvr_dev->irq);
> +       } else {
> +               /*
> +                * Soft reset is triggered as a response to a FW command to the Host and is
> +                * processed from the threaded IRQ handler. This code cannot (nor needs to)
> +                * wait for any IRQ processing to complete.
> +                */
> +               disable_irq_nosync(pvr_dev->irq);
> +       }
> 
>         do {
>                 if (hard_reset) {
> 
> ---
> base-commit: d2e20c8951e4bb5f4a828aed39813599980353b6
> change-id: 20260309-fix-soft-reset-8f32c3783d3d
> 
> Best regards,
> --
> Alessio Belle <alessio.belle@imgtec.com>
> 


-- 
Matt Coster
E: matt.coster@imgtec.com

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