drm/i915: Use non-atomic kmap for slow copy paths

As we do not have a requirement to be atomic and avoid sleeping whilst
performing the slow copy for shmem based pread and pwrite, we can use
kmap instead, thus simplifying the code.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 30 insertions, 52 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 4590c78f4283..b8e351274493 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -167,7 +167,7 @@ static int i915_gem_object_needs_bit17_swizzle(struct drm_gem_object *obj)
                 obj_priv->tiling_mode != I915_TILING_NONE;
 }
 
-static inline int
+static inline void
 slow_shmem_copy(struct page *dst_page,
                 int dst_offset,
                 struct page *src_page,
@@ -176,25 +176,16 @@ slow_shmem_copy(struct page *dst_page,
 {
         char *dst_vaddr, *src_vaddr;
 
-        dst_vaddr = kmap_atomic(dst_page, KM_USER0);
-        if (dst_vaddr == NULL)
-                return -ENOMEM;
-
-        src_vaddr = kmap_atomic(src_page, KM_USER1);
-        if (src_vaddr == NULL) {
-                kunmap_atomic(dst_vaddr, KM_USER0);
-                return -ENOMEM;
-        }
+        dst_vaddr = kmap(dst_page);
+        src_vaddr = kmap(src_page);
 
         memcpy(dst_vaddr + dst_offset, src_vaddr + src_offset, length);
 
-        kunmap_atomic(src_vaddr, KM_USER1);
-        kunmap_atomic(dst_vaddr, KM_USER0);
-
-        return 0;
+        kunmap(src_page);
+        kunmap(dst_page);
 }
 
-static inline int
+static inline void
 slow_shmem_bit17_copy(struct page *gpu_page,
                       int gpu_offset,
                       struct page *cpu_page,
@@ -214,15 +205,8 @@ slow_shmem_bit17_copy(struct page *gpu_page,
                                                cpu_page, cpu_offset, length);
         }
 
-        gpu_vaddr = kmap_atomic(gpu_page, KM_USER0);
-        if (gpu_vaddr == NULL)
-                return -ENOMEM;
-
-        cpu_vaddr = kmap_atomic(cpu_page, KM_USER1);
-        if (cpu_vaddr == NULL) {
-                kunmap_atomic(gpu_vaddr, KM_USER0);
-                return -ENOMEM;
-        }
+        gpu_vaddr = kmap(gpu_page);
+        cpu_vaddr = kmap(cpu_page);
 
         /* Copy the data, XORing A6 with A17 (1). The user already knows he's
          * XORing with the other bits (A9 for Y, A9 and A10 for X)
@@ -246,10 +230,8 @@ slow_shmem_bit17_copy(struct page *gpu_page,
                 length -= this_length;
         }
 
-        kunmap_atomic(cpu_vaddr, KM_USER1);
-        kunmap_atomic(gpu_vaddr, KM_USER0);
-
-        return 0;
+        kunmap(cpu_page);
+        kunmap(gpu_page);
 }
 
 /**
@@ -425,21 +407,19 @@ i915_gem_shmem_pread_slow(struct drm_device *dev, struct drm_gem_object *obj,
                         page_length = PAGE_SIZE - data_page_offset;
 
                 if (do_bit17_swizzling) {
-                        ret = slow_shmem_bit17_copy(obj_priv->pages[shmem_page_index],
-                                                    shmem_page_offset,
-                                                    user_pages[data_page_index],
-                                                    data_page_offset,
-                                                    page_length,
-                                                    1);
-                } else {
-                        ret = slow_shmem_copy(user_pages[data_page_index],
-                                              data_page_offset,
-                                              obj_priv->pages[shmem_page_index],
+                        slow_shmem_bit17_copy(obj_priv->pages[shmem_page_index],
                                               shmem_page_offset,
-                                              page_length);
+                                              user_pages[data_page_index],
+                                              data_page_offset,
+                                              page_length,
+                                              1);
+                } else {
+                        slow_shmem_copy(user_pages[data_page_index],
+                                        data_page_offset,
+                                        obj_priv->pages[shmem_page_index],
+                                        shmem_page_offset,
+                                        page_length);
                 }
-                if (ret)
-                        goto fail_put_pages;
 
                 remain -= page_length;
                 data_ptr += page_length;
@@ -900,21 +880,19 @@ i915_gem_shmem_pwrite_slow(struct drm_device *dev, struct drm_gem_object *obj,
                         page_length = PAGE_SIZE - data_page_offset;
 
                 if (do_bit17_swizzling) {
-                        ret = slow_shmem_bit17_copy(obj_priv->pages[shmem_page_index],
-                                                    shmem_page_offset,
-                                                    user_pages[data_page_index],
-                                                    data_page_offset,
-                                                    page_length,
-                                                    0);
-                } else {
-                        ret = slow_shmem_copy(obj_priv->pages[shmem_page_index],
+                        slow_shmem_bit17_copy(obj_priv->pages[shmem_page_index],
                                               shmem_page_offset,
                                               user_pages[data_page_index],
                                               data_page_offset,
-                                              page_length);
+                                              page_length,
+                                              0);
+                } else {
+                        slow_shmem_copy(obj_priv->pages[shmem_page_index],
+                                        shmem_page_offset,
+                                        user_pages[data_page_index],
+                                        data_page_offset,
+                                        page_length);
                 }
-                if (ret)
-                        goto fail_put_pages;
 
                 remain -= page_length;
                 data_ptr += page_length;