Re: [Intel-gfx] [PATCH 12/19] drm/i915/lmem: Bypass aperture when lmem is available

On 12/04/2021 10:05, Matthew Auld wrote:

From: Anusha Srivatsa anusha.srivatsa@intel.com

In the scenario where local memory is available, we have rely on CPU access via lmem directly instead of aperture.

v2: gmch is only relevant for much older hw, therefore we can drop the has_aperture check since it should always be present on such platforms. (Chris)

Cc: Ville Syrjälä ville.syrjala@linux.intel.com Cc: Dhinakaran Pandiyan dhinakaran.pandiyan@intel.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Chris P Wilson chris.p.wilson@intel.com Cc: Daniel Vetter daniel.vetter@intel.com Cc: Joonas Lahtinen joonas.lahtinen@linux.intel.com Cc: Daniele Ceraolo Spurio daniele.ceraolospurio@intel.com Cc: CQ Tang cq.tang@intel.com Signed-off-by: Anusha Srivatsa anusha.srivatsa@intel.com

---

drivers/gpu/drm/i915/display/intel_fbdev.c | 22 +++++++++++++++------- drivers/gpu/drm/i915/gem/i915_gem_lmem.c | 15 +++++++++++++++ drivers/gpu/drm/i915/gem/i915_gem_lmem.h | 5 +++++ drivers/gpu/drm/i915/i915_vma.c | 19 +++++++++++++------ 4 files changed, 48 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fbdev.c b/drivers/gpu/drm/i915/display/intel_fbdev.c index 2b37959da747..4af40229f5ec 100644 --- a/drivers/gpu/drm/i915/display/intel_fbdev.c +++ b/drivers/gpu/drm/i915/display/intel_fbdev.c @@ -139,14 +139,22 @@ static int intelfb_alloc(struct drm_fb_helper *helper, size = mode_cmd.pitches[0] * mode_cmd.height; size = PAGE_ALIGN(size);

• /* If the FB is too big, just don't use it since fbdev is not very

• * important and we should probably use that space with FBC or other
  

• * features. */
  

  obj = ERR_PTR(-ENODEV);
• if (size * 2 < dev_priv->stolen_usable_size)

• obj = i915_gem_object_create_stolen(dev_priv, size);
  

• if (IS_ERR(obj))

• obj = i915_gem_object_create_shmem(dev_priv, size);
  

• if (HAS_LMEM(dev_priv)) {

• obj = i915_gem_object_create_lmem(dev_priv, size,
  

• 				  I915_BO_ALLOC_CONTIGUOUS);
  

Has to be contiguous? Question for display experts I guess.

[Comes back later.] Ah for iomap? Put a comment to that effect perhaps?

• } else {

• /*
  

•  * If the FB is too big, just don't use it since fbdev is not very
  

•  * important and we should probably use that space with FBC or other
  

•  * features.
  

•  */
  

• if (size * 2 < dev_priv->stolen_usable_size)
  

• 	obj = i915_gem_object_create_stolen(dev_priv, size);
  

• if (IS_ERR(obj))
  

• 	obj = i915_gem_object_create_shmem(dev_priv, size);
  

• }

Could we keep the IS_ERR ordered allocation order to save having to re-indent? Bike shed so optional..

• if (IS_ERR(obj)) { drm_err(&dev_priv->drm, "failed to allocate framebuffer\n"); return PTR_ERR(obj);

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c index 017db8f71130..f44bdd08f7cb 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_lmem.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_lmem.c @@ -17,6 +17,21 @@ const struct drm_i915_gem_object_ops i915_gem_lmem_obj_ops = { .release = i915_gem_object_release_memory_region, };

+void __iomem * +i915_gem_object_lmem_io_map(struct drm_i915_gem_object *obj,

• 	    unsigned long n,
  

• 	    unsigned long size)
  

+{

• resource_size_t offset;
• GEM_BUG_ON(!i915_gem_object_is_contiguous(obj));
• offset = i915_gem_object_get_dma_address(obj, n);
• offset -= obj->mm.region->region.start;
• return io_mapping_map_wc(&obj->mm.region->iomap, offset, size);

+}

• bool i915_gem_object_is_lmem(struct drm_i915_gem_object *obj) { struct intel_memory_region *mr = obj->mm.region;

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_lmem.h b/drivers/gpu/drm/i915/gem/i915_gem_lmem.h index 036d53c01de9..fac6bc5a5ebb 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_lmem.h +++ b/drivers/gpu/drm/i915/gem/i915_gem_lmem.h @@ -14,6 +14,11 @@ struct intel_memory_region;

extern const struct drm_i915_gem_object_ops i915_gem_lmem_obj_ops;

+void __iomem * +i915_gem_object_lmem_io_map(struct drm_i915_gem_object *obj,

• 	    unsigned long n,
  

• 	    unsigned long size);
  

• bool i915_gem_object_is_lmem(struct drm_i915_gem_object *obj);

  struct drm_i915_gem_object *

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c index 07490db51cdc..e24d33aecac4 100644 --- a/drivers/gpu/drm/i915/i915_vma.c +++ b/drivers/gpu/drm/i915/i915_vma.c @@ -27,6 +27,7 @@

#include "display/intel_frontbuffer.h"

+#include "gem/i915_gem_lmem.h" #include "gt/intel_engine.h" #include "gt/intel_engine_heartbeat.h" #include "gt/intel_gt.h" @@ -448,9 +449,11 @@ void __iomem *i915_vma_pin_iomap(struct i915_vma *vma) void __iomem *ptr; int err;

• if (GEM_WARN_ON(!i915_vma_is_map_and_fenceable(vma))) {

• err = -ENODEV;
  

• goto err;
  

• if (!i915_gem_object_is_lmem(vma->obj)) {

• if (GEM_WARN_ON(!i915_vma_is_map_and_fenceable(vma))) {
  

• 	err = -ENODEV;
  

• 	goto err;
  

• }
  

  }

  GEM_BUG_ON(!i915_vma_is_ggtt(vma));

@@ -458,9 +461,13 @@ void __iomem *i915_vma_pin_iomap(struct i915_vma *vma)

ptr = READ_ONCE(vma->iomap); if (ptr == NULL) {

• ptr = io_mapping_map_wc(&i915_vm_to_ggtt(vma->vm)->iomap,
  

• 			vma->node.start,
  

• 			vma->node.size);
  

• if (i915_gem_object_is_lmem(vma->obj))
  

• 	ptr = i915_gem_object_lmem_io_map(vma->obj, 0,
  

• 					  vma->obj->base.size);
  

Can the vma size be bigger than the object here? Given how below works of vma->node.size.

• else
  

• 	ptr = io_mapping_map_wc(&i915_vm_to_ggtt(vma->vm)->iomap,
  

• 				vma->node.start,
  

• 				vma->node.size);
  

Looks a bit odd that this calls the same io_mapping_map_wc as i915_gem_object_lmem_io_map ends up doing. Perhaps that suggests there should be a single helper here but I am not sure what would be elegant.

Regards,

Tvrtko

if (ptr == NULL) {
	err = -ENOMEM;
	goto err;