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

[Raag Jadav <raag.jadav@intel.com>]

On Fri, Jul 11, 2025 at 10:47:39AM +0530, Riana Tauro wrote:
> On 7/11/2025 3:16 AM, Raag Jadav wrote:
> > On Thu, Jul 10, 2025 at 03:00:06PM -0400, Rodrigo Vivi wrote:
> > > On Thu, Jul 10, 2025 at 01:24:52PM +0300, Raag Jadav wrote:
> > > > On Thu, Jul 10, 2025 at 11:37:14AM +0200, Christian König wrote:
> > > > > On 10.07.25 11:01, Simona Vetter wrote:
> > > > > > On Wed, Jul 09, 2025 at 12:52:05PM -0400, Rodrigo Vivi wrote:
> > > > > > > On Wed, Jul 09, 2025 at 05:18:54PM +0300, Raag Jadav wrote:
> > > > > > > > On Wed, Jul 09, 2025 at 04:09:20PM +0200, Christian König wrote:
> > > > > > > > > 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 case here is when FW underneath identified something badly corrupted on
> > > > > > > FW land and decided that only a firmware-flashing could solve the day and
> > > > > > > raise interrupt to the driver. At that point we want to wedge, but immediately
> > > > > > > hint the admin the recommended action.
> > > > > > > 
> > > > > > > > > 
> > > > > > > > > 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.
> > > > > > 
> > > > > > Sorry, I missed that context.
> > > > > > 
> > > > > > > > > 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....
> > > > > > 
> > > > > > Yeah, that's kinda what I expect to happen, and we have enough numbers for
> > > > > > this all to not be an issue.
> > > > > > 
> > > > > > > > Agree. Any newly allocated method that is specific to a vendor is going to
> > > > > > > > be opaque anyway, since it can't be generic for all drivers. This just helps
> > > > > > > > reduce the noise in DRM core.
> > > > > > > > 
> > > > > > > > And yes, there could be different vendor-specific cases for the same driver
> > > > > > > > and the driver should be able to provide the means to distinguish between
> > > > > > > > them.
> > > > > > > 
> > > > > > > Sim, what's your take on this then?
> > > > > > > 
> > > > > > > Should we get back to the original idea of firmware-flash?
> > > > > > 
> > > > > > Maybe intel-firmware-flash or something, meaning prefix with the vendor?
> > > > > > 
> > > > > > The reason I think it should be specific is because I'm assuming you want
> > > > > > to script this. And if you have a big fleet with different vendors, then
> > > > > > "vendor-specific" doesn't tell you enough. But if it's something like
> > > > > > $vendor-$magic_step then it does become scriptable, and we do have have a
> > > > > > place to put some documentation on what you should do instead.
> > > > > > 
> > > > > > If the point of this interface isn't that it's scriptable, then I'm not
> > > > > > sure why it needs to be an uevent?
> > > > > 
> > > > > You should probably read up on the previous discussion, cause that is exactly what I asked as well :)
> > > > > 
> > > > > And no, it should *not* be scripted. That would be a bit brave for a firmware update where you should absolutely not power down the system for example.
> > > 
> > > I also don't like the idea or even the thought of scripting something like
> > > a firmware-flash. But only to fail with a better pin point to make admin
> > > lives easier with a notification.
> > > 
> > > > > 
> > > > > In my understanding the new value "vendor-specific" basically means it is a known issue with a documented solution, while "unknown" means the driver has no idea how to solve it.
> > > 
> > > Exactly, the hardware and firmware are giving the indication of what should be
> > > done. It is not 'unknown'.
> > > 
> > > > 
> > > > Yes, and since the recovery procedure is defined and known to the consumer,
> > > > it can potentially be automated (atleast for non-firmware cases).
> > > > 
> > > > > > I guess if you all want to stick with vendor-specific then I think that's
> > > 
> > > Well, I would honestly prefer a direct firmware-flash, but if that is not
> > > usable by other vendors and there's a push back on that, let's go with
> > > the vendor-specific then.
> > 
> > I think the procedure for firmware-flash is vendor specific, so the wedged event
> > alone is not sufficient either way. The consumer will need more guidance from
> > vendor documentation.
> 
> Procedure of firmware-flash is vendor specific, but the term
> 'firmware-flash' is still generic. The patch doesn't mention any vendor
> specific firmware or procedure. The push back was for the number of macros
> that can be added for other operations.

A common procedure for the methods is what makes them agnostic and usable
for all drivers. Otherwise it's pretty much a chaos for the consumer.

> > With vendor-specific method, the driver has the opportunity to cover as many
> > cases as it wants without having to create a new method everytime, and face the
> > same dilemma of being vendor agnostic.
> > 
> > > > > > ok with me too, but the docs should at least explain how to figure out
> > > > > > from the uevent which vendor you're on with a small example. What I'm
> > > > > > worried is that if we have this on multiple drivers userspace will
> > > > > > otherwise make a complete mess and might want to run the wrong recovery
> > > > > > steps.
> > > > 
> > > > The device id along with driver can be identified from uevent (probably
> > > > available inside DEVPATH somewhere) to distinguish the vendor. So the consumer
> > > > already knows if the device fits the criteria for recovery.
> > > > 
> > > > > > I think ideally, no matter what, we'd have a concrete driver patch which
> > > > > > then also comes with the documentation for what exactly you're supposed to
> > > > > > do as something you can script. And not just this stand-alone patch here.
> > > > 
> > > > Perhaps the rest of the series didn't make it to dri-devel, which will answer
> > > > most of the above.
> > > 
> > > Riana, could you please try to provide a bit more documentation like Sima
> > > asked and re-send the entire series to dri-devel?
> 
> Sure will send the entire series to dri-devel. The documentation is present
> in the series.
> 
> > 
> > With the ideas in this thread also documented so that we don't end up repeating
> > the same discussion.
> It is mentioned in cover letter but i didn't send it to dri-devel. will add
> more details

Thank you.

Raag

> > > > > > > > > > > ---
> > > > > > > > > > >   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
> > > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > 
> > > > > > 
> > > > > 
> 
>