On 2022-05-13 at 14:06:11 -0700, Jordan Justen wrote:
> On 2022-05-13 05:31:00, Lionel Landwerlin wrote:
> > On 02/05/2022 17:15, Ramalingam C wrote:
> > > Capture the impact of memory region preference list of the objects, on
> > > their memory residency and Flat-CCS capability.
> > >
> > > v2:
> > > Fix the Flat-CCS capability of an obj with {lmem, smem} preference
> > > list [Thomas]
> > > v3:
> > > Reworded the doc [Matt]
> > >
> > > Signed-off-by: Ramalingam C <[email protected]>
> > > cc: Matthew Auld <[email protected]>
> > > cc: Thomas Hellstrom <[email protected]>
> > > cc: Daniel Vetter <[email protected]>
> > > cc: Jon Bloomfield <[email protected]>
> > > cc: Lionel Landwerlin <[email protected]>
> > > cc: Kenneth Graunke <[email protected]>
> > > cc: [email protected]
> > > cc: Jordan Justen <[email protected]>
> > > cc: Tony Ye <[email protected]>
> > > Reviewed-by: Matthew Auld <[email protected]>
> > > ---
> > > include/uapi/drm/i915_drm.h | 16 ++++++++++++++++
> > > 1 file changed, 16 insertions(+)
> > >
> > > diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> > > index a2def7b27009..b7e1c2fe08dc 100644
> > > --- a/include/uapi/drm/i915_drm.h
> > > +++ b/include/uapi/drm/i915_drm.h
> > > @@ -3443,6 +3443,22 @@ struct drm_i915_gem_create_ext {
> > > * At which point we get the object handle in
> > > &drm_i915_gem_create_ext.handle,
> > > * along with the final object size in &drm_i915_gem_create_ext.size,
> > > which
> > > * should account for any rounding up, if required.
> > > + *
> > > + * Note that userspace has no means of knowing the current backing region
> > > + * for objects where @num_regions is larger than one. The kernel will
> > > only
> > > + * ensure that the priority order of the @regions array is honoured,
> > > either
> > > + * when initially placing the object, or when moving memory around due to
> > > + * memory pressure
> > > + *
> > > + * On Flat-CCS capable HW, compression is supported for the objects
> > > residing
> > > + * in I915_MEMORY_CLASS_DEVICE. When such objects (compressed) has other
> > > + * memory class in @regions and migrated (by I915, due to memory
> > > + * constrain) to the non I915_MEMORY_CLASS_DEVICE region, then I915
> > > needs to
> > > + * decompress the content. But I915 dosen't have the required
> > > information to
> > > + * decompress the userspace compressed objects.
> > > + *
> > > + * So I915 supports Flat-CCS, only on the objects which can reside only
> > > on
> > > + * I915_MEMORY_CLASS_DEVICE regions.
> >
> > I think it's fine to assume Flat-CSS surface will always be in lmem.
> >
> > I see no issue for the Anv Vulkan driver.
> >
> > Maybe Nanley or Ken can speak for the Iris GL driver?
> >
>
> Acked-by: Jordan Justen <[email protected]>
Thank you Jordan for the Ack!
Ram
>
> I think Nanley has accounted for this on iris with:
>
> https://gitlab.freedesktop.org/mesa/mesa/-/commit/42a865730ef72574e179b56a314f30fdccc6cba8
>
> -Jordan
