[Intel-gfx] [PATCH v2 4/7] drm/i915/uc: Don't use -EIO to report missing firmware

[Chris Wilson]

Quoting Michal Wajdeczko (2017-12-01 10:33:14)
> -EIO has special meaning and is used when we want to allow
> engine initialization to fail and mark GPU as wedged.
> Missing firmware does not fit into this scenario as this is
> permanent error not related to GPU condition.
> 
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Sagar Arun Kamble <sagar.a.kamble at intel.com>

Ok, keeping -EIO to mean something special is a good idea. So if upload
now fails, we abort loading of the driver with ENOEXEC.

Is that sensible? Let's say due to fs corruption, or other error, we
aren't able to upload a fw, what should we do? If we abort the driver
load at this point, the user is likely left with a blank screen. If we
use -EIO, at least KMS is still functional and the user can still
interact with the system. (If we just fell back to execlists, then the
system remains very usable.)

What is the plan for HW initialisation failure?
-Chris