Re: [Intel-gfx] [PATCH v3 4/6] drm/i915/gt: Register the migrate contexts with their engines

[Matthew Auld <matthew.auld@intel.com>]

On 14/09/2021 20:31, Thomas Hellström wrote:
> Pinned contexts, like the migrate contexts need reset after resume
> since their context image may have been lost. Also the GuC needs to
> register pinned contexts.
> 
> Add a list to struct intel_engine_cs where we add all pinned contexts on
> creation, and traverse that list at resume time to reset the pinned
> contexts.
> 
> This fixes the kms_pipe_crc_basic@suspend-read-crc-pipe-a selftest for now,
> but proper LMEM backup / restore is needed for full suspend functionality.
> However, note that even with full LMEM backup / restore it may be
> desirable to keep the reset since backing up the migrate context images
> must happen using memcpy() after the migrate context has become inactive,
> and for performance- and other reasons we want to avoid memcpy() from
> LMEM.
> 
> Also traverse the list at guc_init_lrc_mapping() calling
> guc_kernel_context_pin() for the pinned contexts, like is already done
> for the kernel context.
> 
> v2:
> - Don't reset the contexts on each __engine_unpark() but rather at
>    resume time (Chris Wilson).
> v3:
> - Reset contexts in the engine sanitize callback. (Chris Wilson)
> 
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Brost Matthew <matthew.brost@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>