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

["Christian König" <christian.koenig@amd.com>]

On 09.07.25 15:41, Simona Vetter wrote:
> 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 recovery method for this particular case is to flash in a new firmware.

> 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.

That is exactly the opposite of what we discussed so far.

The original idea was to add a firmware-flush recovery method which looked a bit wage since it didn't give any information on what to do exactly.

That's why I suggested to add a more generic vendor-specific event with refers to the documentation and system log to see what actually needs to be done.

Otherwise we would end up with events like firmware-flash, update FW image A, update FW image B, FW version mismatch etc....

Regards,
Christian.

> 
> 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
>>
>