[PATCH v6 1/4] drm: Introduce device wedged event

[Raag Jadav]

On Tue, Sep 24, 2024 at 01:23:13PM +0200, Simona Vetter wrote:
> On Mon, Sep 23, 2024 at 09:28:23AM +0530, Raag Jadav wrote:
> > Introduce device wedged event, which will notify userspace of wedged
> > (hanged/unusable) state of the DRM device through a uevent. This is
> > useful especially in cases where the device is no longer operating as
> > expected and has become unrecoverable from driver context.
> > 
> > Purpose of this implementation is to provide drivers a way to recover
> > through userspace intervention. Different drivers may have different
> > ideas of a "wedged device" depending on their hardware implementation,
> > and hence the vendor agnostic nature of the event. It is up to the drivers
> > to decide when they see the need for recovery and how they want to recover
> > from the available methods.
> > 
> > Current implementation defines three recovery methods, out of which,
> > drivers can choose to support any one or multiple of them. Preferred
> > recovery method will be sent in the uevent environment as WEDGED=<method>.
> > Userspace consumers (sysadmin) can define udev rules to parse this event
> > and take respective action to recover the device.
> > 
> >  Method    | Consumer expectations
> > -----------|-----------------------------------
> >  rebind    | unbind + rebind driver
> >  bus-reset | unbind + reset bus device + rebind
> >  reboot    | reboot system
> > 
> > v4: s/drm_dev_wedged/drm_dev_wedged_event
> >     Use drm_info() (Jani)
> >     Kernel doc adjustment (Aravind)
> > v5: Send recovery method with uevent (Lina)
> > v6: Access wedge_recovery_opts[] using helper function (Jani)
> >     Use snprintf() (Jani)
> > 
> > Signed-off-by: Raag Jadav <raag.jadav at intel.com>
> 
> Finally caught up on mail, so dropping this here again: Please also add a
> small section to drm-uapi.rst, pointing at these functions. Just the
> kerneldoc for developers is kinda not enough I think.

Would you prefer a new section or have the existing one (Device reset which
looks somewhat similar but not entirely) modified?

Raag