Re: [PATCH v4 1/9] drm: Add a vendor-specific recovery method to device wedged uevent

[Simona Vetter <simona.vetter@ffwll.ch>]

On Wed, Jul 09, 2025 at 04:50:13PM +0530, Riana Tauro wrote:
> Certain errors can cause the device to be wedged and may
> require a vendor specific recovery method to restore normal
> operation.
> 
> Add a recovery method 'WEDGED=vendor-specific' for such errors. Vendors
> must provide additional recovery documentation if this method
> is used.
> 
> v2: fix documentation (Raag)
> 
> Cc: André Almeida <andrealmeid@igalia.com>
> Cc: Christian König <christian.koenig@amd.com>
> Cc: David Airlie <airlied@gmail.com>
> Cc: <dri-devel@lists.freedesktop.org>
> Suggested-by: Raag Jadav <raag.jadav@intel.com>
> Signed-off-by: Riana Tauro <riana.tauro@intel.com>

I'm not really understanding what this is useful for, maybe concrete
example in the form of driver code that uses this, and some tool or
documentation steps that should be taken for recovery?

The issues I'm seeing here is that eventually we'll get different
vendor-specific recovery steps, and maybe even on the same device, and
that leads us to an enumeration issue. Since it's just a string and an
enum I think it'd be better to just allocate a new one every time there's
a new strange recovery method instead of this opaque approach.

Cheers, Sima

> ---
>  Documentation/gpu/drm-uapi.rst | 9 +++++----
>  drivers/gpu/drm/drm_drv.c      | 2 ++
>  include/drm/drm_device.h       | 4 ++++
>  3 files changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst
> index 263e5a97c080..c33070bdb347 100644
> --- a/Documentation/gpu/drm-uapi.rst
> +++ b/Documentation/gpu/drm-uapi.rst
> @@ -421,10 +421,10 @@ Recovery
>  Current implementation defines three recovery methods, out of which, drivers
>  can use any one, multiple or none. Method(s) of choice will be sent in the
>  uevent environment as ``WEDGED=<method1>[,..,<methodN>]`` in order of less to
> -more side-effects. If driver is unsure about recovery or method is unknown
> -(like soft/hard system reboot, firmware flashing, physical device replacement
> -or any other procedure which can't be attempted on the fly), ``WEDGED=unknown``
> -will be sent instead.
> +more side-effects. If recovery method is specific to vendor
> +``WEDGED=vendor-specific`` will be sent and userspace should refer to vendor
> +specific documentation for further recovery steps. If driver is unsure about
> +recovery or method is unknown, ``WEDGED=unknown`` will be sent instead
>  
>  Userspace consumers can parse this event and attempt recovery as per the
>  following expectations.
> @@ -435,6 +435,7 @@ following expectations.
>      none            optional telemetry collection
>      rebind          unbind + bind driver
>      bus-reset       unbind + bus reset/re-enumeration + bind
> +    vendor-specific vendor specific recovery method
>      unknown         consumer policy
>      =============== ========================================
>  
> diff --git a/drivers/gpu/drm/drm_drv.c b/drivers/gpu/drm/drm_drv.c
> index cdd591b11488..0ac723a46a91 100644
> --- a/drivers/gpu/drm/drm_drv.c
> +++ b/drivers/gpu/drm/drm_drv.c
> @@ -532,6 +532,8 @@ static const char *drm_get_wedge_recovery(unsigned int opt)
>  		return "rebind";
>  	case DRM_WEDGE_RECOVERY_BUS_RESET:
>  		return "bus-reset";
> +	case DRM_WEDGE_RECOVERY_VENDOR:
> +		return "vendor-specific";
>  	default:
>  		return NULL;
>  	}
> diff --git a/include/drm/drm_device.h b/include/drm/drm_device.h
> index 08b3b2467c4c..08a087f149ff 100644
> --- a/include/drm/drm_device.h
> +++ b/include/drm/drm_device.h
> @@ -26,10 +26,14 @@ struct pci_controller;
>   * Recovery methods for wedged device in order of less to more side-effects.
>   * To be used with drm_dev_wedged_event() as recovery @method. Callers can
>   * use any one, multiple (or'd) or none depending on their needs.
> + *
> + * Refer to "Device Wedging" chapter in Documentation/gpu/drm-uapi.rst for more
> + * details.
>   */
>  #define DRM_WEDGE_RECOVERY_NONE		BIT(0)	/* optional telemetry collection */
>  #define DRM_WEDGE_RECOVERY_REBIND	BIT(1)	/* unbind + bind driver */
>  #define DRM_WEDGE_RECOVERY_BUS_RESET	BIT(2)	/* unbind + reset bus device + bind */
> +#define DRM_WEDGE_RECOVERY_VENDOR	BIT(3)	/* vendor specific recovery method */
>  
>  /**
>   * struct drm_wedge_task_info - information about the guilty task of a wedge dev
> -- 
> 2.47.1
> 

-- 
Simona Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch