Commit cecab0bb authored by Andi Shyti's avatar Andi Shyti
Browse files

drm/i915/gem: Improve pfn calculation readability in vm_fault_gtt() 



By moving the pfn calculation to the set_address_limits()
function we improve code readability. This way,
set_address_limits() is responsible for calculating all memory
mapping paramenters: "start", "end" and "pfn".

This suggestion from Jonathan was made during the review of
commit 8bdd9ef7 ("drm/i915/gem: Fix Virtual Memory mapping
boundaries calculation"), which I liked, but it got lost on the
way.

Suggested-by: default avatarJonathan Cavitt <Jonathan.cavitt@intel.com>
Signed-off-by: default avatarAndi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: default avatarKrzysztof Niemiec <krzysztof.niemiec@intel.com>
Reviewed-by: default avatarJonathan Cavitt <jonathan.cavitt@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240807104553.481763-1-andi.shyti@linux.intel.com
parent 0829b5bc

drivers/gpu/drm/i915/gem/i915_gem_mman.c

+14 −6
Original line number Diff line number Diff line
@@ -293,8 +293,10 @@ static vm_fault_t vm_fault_cpu(struct vm_fault *vmf) 
static void set_address_limits(struct vm_area_struct *area,

			       struct i915_vma *vma,

			       unsigned long obj_offset,

			       resource_size_t gmadr_start,

			       unsigned long *start_vaddr,

			       unsigned long *end_vaddr)

			       unsigned long *end_vaddr,

			       unsigned long *pfn)

{

	unsigned long vm_start, vm_end, vma_size; /* user's memory parameters */

	long start, end; /* memory boundaries */
@@ -323,6 +325,10 @@ static void set_address_limits(struct vm_area_struct *area, 
	/* Let's move back into the "<< PAGE_SHIFT" domain */

	*start_vaddr = (unsigned long)start << PAGE_SHIFT;

	*end_vaddr = (unsigned long)end << PAGE_SHIFT;



	*pfn = (gmadr_start + i915_ggtt_offset(vma)) >> PAGE_SHIFT;

	*pfn += (*start_vaddr - area->vm_start) >> PAGE_SHIFT;

	*pfn += obj_offset - vma->gtt_view.partial.offset;

}



static vm_fault_t vm_fault_gtt(struct vm_fault *vmf)
@@ -441,11 +447,13 @@ static vm_fault_t vm_fault_gtt(struct vm_fault *vmf) 
	if (ret)

		goto err_unpin;



	set_address_limits(area, vma, obj_offset, &start, &end);



	pfn = (ggtt->gmadr.start + i915_ggtt_offset(vma)) >> PAGE_SHIFT;

	pfn += (start - area->vm_start) >> PAGE_SHIFT;

	pfn += obj_offset - vma->gtt_view.partial.offset;

	/*

	 * Dump all the necessary parameters in this function to perform the

	 * arithmetic calculation for the virtual address start and end and

	 * the PFN (Page Frame Number).

	 */

	set_address_limits(area, vma, obj_offset, ggtt->gmadr.start,

			   &start, &end, &pfn);



	/* Finally, remap it using the new GTT offset */

	ret = remap_io_mapping(area, start, pfn, end - start, &ggtt->iomap);