drm/gma500: Rewrite GTT page insert/remove without struct gtt_range

struct gtt_range represents a GEM object and should not be used for GTT
setup. Change psb_gtt_insert() and psb_gtt_remove() to receive all
necessary parameters from their caller. This also eliminates possible
failure from psb_gtt_insert().

There's one exception in psb_gtt_restore(), which requires an upcast
from struct resource to struct gtt_range when restoring the GTT after
hibernation. A possible solution would track the GEM objects that need
restoration separately from the GTT resource.

Rename the functions to psb_gtt_insert_pages() and psb_gtt_remove_pages()
to reflect their similarity to MMU interfaces.

v3:
	* restore the comments about locking rules (Patrik)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Patrik Jakobsson <patrik.r.jakobsson@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211015084053.13708-10-tzimmermann@suse.de

drivers/gpu/drm/gma500/gem.c

@@ -23,12 +23,12 @@
 
 int psb_gem_pin(struct gtt_range *gt)
 {
-	int ret = 0;
 	struct drm_device *dev = gt->gem.dev;
 	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
 	u32 gpu_base = dev_priv->gtt.gatt_start;
 	struct page **pages;
 	unsigned int npages;
+	int ret;
 
 	mutex_lock(&dev_priv->gtt_mutex);
 
@@ -45,10 +45,7 @@ int psb_gem_pin(struct gtt_range *gt)
 
 	set_pages_array_wc(pages, npages);
 
-	ret = psb_gtt_insert(dev, gt);
-	if (ret)
-		goto err_drm_gem_put_pages;
-
+	psb_gtt_insert_pages(dev_priv, &gt->resource, pages);
 	psb_mmu_insert_pages(psb_mmu_get_default_pd(dev_priv->mmu), pages,
 			     (gpu_base + gt->offset), npages, 0, 0,
 			     PSB_MMU_CACHED_MEMORY);
@@ -62,8 +59,6 @@ int psb_gem_pin(struct gtt_range *gt)
 
 	return 0;
 
-err_drm_gem_put_pages:
-	drm_gem_put_pages(&gt->gem, pages, true, false);
 err_mutex_unlock:
 	mutex_unlock(&dev_priv->gtt_mutex);
 	return ret;
@@ -86,13 +81,14 @@ void psb_gem_unpin(struct gtt_range *gt)
 
 	psb_mmu_remove_pages(psb_mmu_get_default_pd(dev_priv->mmu),
 				     (gpu_base + gt->offset), gt->npage, 0, 0);
-	psb_gtt_remove(dev, gt);
+	psb_gtt_remove_pages(dev_priv, &gt->resource);
 
 	/* Reset caching flags */
 	set_pages_array_wb(gt->pages, gt->npage);
 
 	drm_gem_put_pages(&gt->gem, gt->pages, true, false);
 	gt->pages = NULL;
+	gt->npage = 0;
 
 out:
 	mutex_unlock(&dev_priv->gtt_mutex);

drivers/gpu/drm/gma500/gtt.c

@@ -66,85 +66,61 @@ static inline uint32_t psb_gtt_mask_pte(uint32_t pfn, int type)
 	return (pfn << PAGE_SHIFT) | mask;
 }
 
-/**
- *	psb_gtt_entry		-	find the GTT entries for a gtt_range
- *	@dev: our DRM device
- *	@r: our GTT range
- *
- *	Given a gtt_range object return the GTT offset of the page table
- *	entries for this gtt_range
- */
-static u32 __iomem *psb_gtt_entry(struct drm_device *dev, struct gtt_range *r)
+static u32 __iomem *psb_gtt_entry(struct drm_psb_private *pdev, const struct resource *res)
 {
-	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
-	unsigned long offset;
-
-	offset = r->resource.start - dev_priv->gtt_mem->start;
+	unsigned long offset = res->start - pdev->gtt_mem->start;
 
-	return dev_priv->gtt_map + (offset >> PAGE_SHIFT);
+	return pdev->gtt_map + (offset >> PAGE_SHIFT);
 }
 
-/**
- *	psb_gtt_insert	-	put an object into the GTT
- *	@dev: our DRM device
- *	@r: our GTT range
- *
+/*
  * Take our preallocated GTT range and insert the GEM object into
  * the GTT. This is protected via the gtt mutex which the caller
  * must hold.
  */
-int psb_gtt_insert(struct drm_device *dev, struct gtt_range *r)
+void psb_gtt_insert_pages(struct drm_psb_private *pdev, const struct resource *res,
+			  struct page **pages)
 {
+	resource_size_t npages, i;
 	u32 __iomem *gtt_slot;
 	u32 pte;
-	int i;
-
-	if (r->pages == NULL) {
-		WARN_ON(1);
-		return -EINVAL;
-	}
 
-	WARN_ON(r->stolen);	/* refcount these maybe ? */
+	/* Write our page entries into the GTT itself */
 
-	gtt_slot = psb_gtt_entry(dev, r);
+	npages = resource_size(res) >> PAGE_SHIFT;
+	gtt_slot = psb_gtt_entry(pdev, res);
 
-	/* Write our page entries into the GTT itself */
-	for (i = 0; i < r->npage; i++) {
-		pte = psb_gtt_mask_pte(page_to_pfn(r->pages[i]),
-				       PSB_MMU_CACHED_MEMORY);
-		iowrite32(pte, gtt_slot++);
+	for (i = 0; i < npages; ++i, ++gtt_slot) {
+		pte = psb_gtt_mask_pte(page_to_pfn(pages[i]), PSB_MMU_CACHED_MEMORY);
+		iowrite32(pte, gtt_slot);
 	}
 
 	/* Make sure all the entries are set before we return */
 	ioread32(gtt_slot - 1);
-
-	return 0;
 }
 
-/**
- *	psb_gtt_remove	-	remove an object from the GTT
- *	@dev: our DRM device
- *	@r: our GTT range
- *
+/*
  * Remove a preallocated GTT range from the GTT. Overwrite all the
  * page table entries with the dummy page. This is protected via the gtt
  * mutex which the caller must hold.
  */
-void psb_gtt_remove(struct drm_device *dev, struct gtt_range *r)
+void psb_gtt_remove_pages(struct drm_psb_private *pdev, const struct resource *res)
 {
-	struct drm_psb_private *dev_priv = to_drm_psb_private(dev);
+	resource_size_t npages, i;
 	u32 __iomem *gtt_slot;
 	u32 pte;
-	int i;
 
-	WARN_ON(r->stolen);
+	/* Install scratch page for the resource */
 
-	gtt_slot = psb_gtt_entry(dev, r);
-	pte = psb_gtt_mask_pte(page_to_pfn(dev_priv->scratch_page),
-			       PSB_MMU_CACHED_MEMORY);
+	pte = psb_gtt_mask_pte(page_to_pfn(pdev->scratch_page), PSB_MMU_CACHED_MEMORY);
 
-	for (i = 0; i < r->npage; i++)
-		iowrite32(pte, gtt_slot++);
+	npages = resource_size(res) >> PAGE_SHIFT;
+	gtt_slot = psb_gtt_entry(pdev, res);
+
+	for (i = 0; i < npages; ++i, ++gtt_slot)
+		iowrite32(pte, gtt_slot);
+
+	/* Make sure all the entries are set before we return */
 	ioread32(gtt_slot - 1);
 }
 
@@ -334,9 +310,14 @@ int psb_gtt_restore(struct drm_device *dev)
 	psb_gtt_init(dev, 1);
 
 	while (r != NULL) {
+		/*
+		 * TODO: GTT restoration needs a refactoring, so that we don't have to touch
+		 *       struct gtt_range here. The type represents a GEM object and is not
+		 *       related to the GTT itself.
+		 */
 		range = container_of(r, struct gtt_range, resource);
 		if (range->pages) {
-			psb_gtt_insert(dev, range);
+			psb_gtt_insert_pages(dev_priv, &range->resource, range->pages);
 			size += range->resource.end - range->resource.start;
 			restored++;
 		}

drivers/gpu/drm/gma500/gtt.h

@@ -49,7 +49,8 @@ int psb_gtt_allocate_resource(struct drm_psb_private *pdev, struct resource *res
 			      const char *name, resource_size_t size, resource_size_t align,
 			      bool stolen, u32 *offset);
 
-int psb_gtt_insert(struct drm_device *dev, struct gtt_range *r);
-void psb_gtt_remove(struct drm_device *dev, struct gtt_range *r);
+void psb_gtt_insert_pages(struct drm_psb_private *pdev, const struct resource *res,
+			  struct page **pages);
+void psb_gtt_remove_pages(struct drm_psb_private *pdev, const struct resource *res);
 
 #endif