[Intel-gfx] [PATCH v5 04/18] drm/i915/tdr: Modify error handler for per engine hang recovery

[Chris Wilson]

On Fri, Mar 24, 2017 at 06:29:56PM -0700, Michel Thierry wrote:
> From: Arun Siluvery <arun.siluvery at linux.intel.com>
> 
> This is a preparatory patch which modifies error handler to do per engine
> hang recovery. The actual patch which implements this sequence follows
> later in the series. The aim is to prepare existing recovery function to
> adapt to this new function where applicable (which fails at this point
> because core implementation is lacking) and continue recovery using legacy
> full gpu reset.
> 
> A helper function is also added to query the availability of engine
> reset.
> 
> The error events behaviour that are used to notify user of reset are
> adapted to engine reset such that it doesn't break users listening to these
> events. In legacy we report an error event, a reset event before resetting
> the gpu and a reset done event marking the completion of reset. The same
> behaviour is adapted but reset event is only dispatched once even when
> multiple engines are hung. Finally once reset is complete we send reset
> done event as usual.
> 
> Note that this implementation of engine reset is for i915 directly
> submitting to the ELSP, where the driver manages the hang detection,
> recovery and resubmission. With GuC submission these tasks are shared
> between driver and firmware; i915 will still responsible for detecting a
> hang, and when it does it will have to request GuC to reset that Engine and
> remind the firmware about the outstanding submissions. This will be
> added in different patch.
> 
> v2: rebase, advertise engine reset availability in platform definition,
> add note about GuC submission.
> v3: s/*engine_reset*/*reset_engine*/. (Chris)
> Handle reset as 2 level resets, by first going to engine only and fall
> backing to full/chip reset as needed, i.e. reset_engine will need the
> struct_mutex.
> v4: Pass the engine mask to i915_reset. (Chris)
> v5: Rebase, update selftests.
> 
> Cc: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> Signed-off-by: Ian Lister <ian.lister at intel.com>
> Signed-off-by: Tomas Elf <tomas.elf at intel.com>
> Signed-off-by: Arun Siluvery <arun.siluvery at linux.intel.com>
> Signed-off-by: Michel Thierry <michel.thierry at intel.com>

4 authors in and this patch is still trying to do reset_engine until the
mutex, requiring the handoff. Why? We should be ready now to be able to
do the first pass of resets before the mutex - we don't need to even
prepare the display for the per-engine resets and should be able to do
it much lighter. We can land the per-engine struct_mutex resets for
hangcheck as soon as it is ready as it would see immediate testing.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre