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* [PATCH v3] uapi/drm/i915: Document memory residency and Flat-CCS capability of obj
@ 2022-05-02 14:15 ` Ramalingam C
  0 siblings, 0 replies; 17+ messages in thread
From: Ramalingam C @ 2022-05-02 14:15 UTC (permalink / raw)
  To: intel-gfx, dri-devel
  Cc: Tony Ye, Thomas Hellstrom, Jordan Justen, Daniel Vetter,
	Lionel Landwerlin, Kenneth Graunke, Jon Bloomfield, Matthew Auld,
	mesa-dev

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 <ramalingam.c@intel.com>
cc: Matthew Auld <matthew.auld@intel.com>
cc: Thomas Hellstrom <thomas.hellstrom@linux.intel.com>
cc: Daniel Vetter <daniel.vetter@ffwll.ch>
cc: Jon Bloomfield <jon.bloomfield@intel.com>
cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
cc: Kenneth Graunke <kenneth@whitecape.org>
cc: mesa-dev@lists.freedesktop.org
cc: Jordan Justen <jordan.l.justen@intel.com>
cc: Tony Ye <tony.ye@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
---
 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.
  */
 struct drm_i915_gem_create_ext_memory_regions {
 	/** @base: Extension link. See struct i915_user_extension. */
-- 
2.20.1


^ permalink raw reply related	[flat|nested] 17+ messages in thread
end of thread, other threads:[~2022-05-18 18:44 UTC | newest]

Thread overview: 17+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-02 14:15 [PATCH v3] uapi/drm/i915: Document memory residency and Flat-CCS capability of obj Ramalingam C
2022-05-02 14:15 ` [Intel-gfx] " Ramalingam C
2022-05-02 14:29 ` [Intel-gfx] ✗ Fi.CI.SPARSE: warning for " Patchwork
2022-05-02 14:54 ` [Intel-gfx] ✓ Fi.CI.BAT: success " Patchwork
2022-05-02 17:46 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
2022-05-13 12:31 ` [PATCH v3] " Lionel Landwerlin
2022-05-13 12:31   ` [Intel-gfx] " Lionel Landwerlin
2022-05-13 21:06   ` Jordan Justen
2022-05-13 21:06     ` [Intel-gfx] " Jordan Justen
2022-05-16  7:47     ` Lionel Landwerlin
2022-05-16  7:47       ` [Intel-gfx] " Lionel Landwerlin
2022-05-16  8:07       ` Jordan Justen
2022-05-16  8:07         ` [Intel-gfx] " Jordan Justen
2022-05-18  6:52     ` Ramalingam C
2022-05-18  6:52       ` [Intel-gfx] " Ramalingam C
2022-05-18 18:41 ` Ye, Tony
2022-05-18 18:41   ` [Intel-gfx] " Ye, Tony

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