Re: [PATCH v2 5/6] drm/i915: Don't back up pinned LMEM context images and rings during suspend

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

On Wed, 2021-09-08 at 12:07 +0100, Matthew Auld wrote:
> On 06/09/2021 17:55, Thomas Hellström wrote:
> > Pinned context images are now reset during resume. Don't back them
> > up,
> > and assuming that rings can be assumed empty at suspend, don't back
> > them
> > up either.
> > 
> > Introduce a new object flag, I915_BO_ALLOC_PM_VOLATILE meaning that
> > an
> > object is allowed to lose its content on suspend.
> > 
> > Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> > ---
> >   .../gpu/drm/i915/gem/i915_gem_object_types.h    | 17 ++++++++++--
> > -----
> >   drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c      |  3 +++
> >   drivers/gpu/drm/i915/gt/intel_lrc.c             |  3 ++-
> >   drivers/gpu/drm/i915/gt/intel_ring.c            |  3 ++-
> >   4 files changed, 17 insertions(+), 9 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> > b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> > index 734cc8e16481..66123ba46247 100644
> > --- a/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> > +++ b/drivers/gpu/drm/i915/gem/i915_gem_object_types.h
> > @@ -288,16 +288,19 @@ struct drm_i915_gem_object {
> >         I915_SELFTEST_DECLARE(struct list_head st_link);
> >   
> >         unsigned long flags;
> > -#define I915_BO_ALLOC_CONTIGUOUS BIT(0)
> > -#define I915_BO_ALLOC_VOLATILE   BIT(1)
> > -#define I915_BO_ALLOC_CPU_CLEAR  BIT(2)
> > -#define I915_BO_ALLOC_USER       BIT(3)
> > +#define I915_BO_ALLOC_CONTIGUOUS  BIT(0)
> > +#define I915_BO_ALLOC_VOLATILE    BIT(1)
> > +#define I915_BO_ALLOC_CPU_CLEAR   BIT(2)
> > +#define I915_BO_ALLOC_USER        BIT(3)
> > +/* Object may lose its contents on suspend / resume */
> > +#define I915_BO_ALLOC_PM_VOLATILE BIT(4)

> 
> PM_SKIP_PINNED? Not sure if that is better.

I think we could update the comment to say "object is allowed to
lose..", I think we could keep PM_VOLATILE to keep it consistent with
the ALLOC_VOLATILE flag?

/Thomas