drm/i915: Allow tiling of objects with bit 17 swizzling by the CPU.

Save the bit 17 state of the pages when freeing the page list, and
reswizzle them if necessary when rebinding the pages (in case they were
swapped out).  Since we have userland with expectations that the swizzle
enums let it pread and pwrite contents accurately, we can't expose a new
swizzle enum for bit 17 (which it would have to GTT map to handle), so we
handle it down in pread and pwrite by swizzling the copy when bit 17 of the
page address is set.

Signed-off-by: Eric Anholt <eric@anholt.net>

1 files changed, 109 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
index 6be3f92..f27e523 100644
--- a/drivers/gpu/drm/i915/i915_gem_tiling.c
+++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
@@ -25,6 +25,8 @@
  *
  */
 
+#include "linux/string.h"
+#include "linux/bitops.h"
 #include "drmP.h"
 #include "drm.h"
 #include "i915_drm.h"
@@ -127,8 +129,8 @@ i915_gem_detect_bit_6_swizzle(struct drm_device *dev)
 				swizzle_y = I915_BIT_6_SWIZZLE_9_11;
 			} else {
 				/* Bit 17 swizzling by the CPU in addition. */
-				swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN;
-				swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;
+				swizzle_x = I915_BIT_6_SWIZZLE_9_10_17;
+				swizzle_y = I915_BIT_6_SWIZZLE_9_17;
 			}
 			break;
 		}
@@ -288,6 +290,19 @@ i915_gem_set_tiling(struct drm_device *dev, void *data,
 			args->swizzle_mode = dev_priv->mm.bit_6_swizzle_x;
 		else
 			args->swizzle_mode = dev_priv->mm.bit_6_swizzle_y;
+
+		/* Hide bit 17 swizzling from the user.  This prevents old Mesa
+		 * from aborting the application on sw fallbacks to bit 17,
+		 * and we use the pread/pwrite bit17 paths to swizzle for it.
+		 * If there was a user that was relying on the swizzle
+		 * information for drm_intel_bo_map()ed reads/writes this would
+		 * break it, but we don't have any of those.
+		 */
+		if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_17)
+			args->swizzle_mode = I915_BIT_6_SWIZZLE_9;
+		if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17)
+			args->swizzle_mode = I915_BIT_6_SWIZZLE_9_10;
+
 		/* If we can't handle the swizzling, make it untiled. */
 		if (args->swizzle_mode == I915_BIT_6_SWIZZLE_UNKNOWN) {
 			args->tiling_mode = I915_TILING_NONE;
@@ -354,8 +369,100 @@ i915_gem_get_tiling(struct drm_device *dev, void *data,
 		DRM_ERROR("unknown tiling mode\n");
 	}
 
+	/* Hide bit 17 from the user -- see comment in i915_gem_set_tiling */
+	if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_17)
+		args->swizzle_mode = I915_BIT_6_SWIZZLE_9;
+	if (args->swizzle_mode == I915_BIT_6_SWIZZLE_9_10_17)
+		args->swizzle_mode = I915_BIT_6_SWIZZLE_9_10;
+
 	drm_gem_object_unreference(obj);
 	mutex_unlock(&dev->struct_mutex);
 
 	return 0;
 }
+
+/**
+ * Swap every 64 bytes of this page around, to account for it having a new
+ * bit 17 of its physical address and therefore being interpreted differently
+ * by the GPU.
+ */
+static int
+i915_gem_swizzle_page(struct page *page)
+{
+	char *vaddr;
+	int i;
+	char temp[64];
+
+	vaddr = kmap(page);
+	if (vaddr == NULL)
+		return -ENOMEM;
+
+	for (i = 0; i < PAGE_SIZE; i += 128) {
+		memcpy(temp, &vaddr[i], 64);
+		memcpy(&vaddr[i], &vaddr[i + 64], 64);
+		memcpy(&vaddr[i + 64], temp, 64);
+	}
+
+	kunmap(page);
+
+	return 0;
+}
+
+void
+i915_gem_object_do_bit_17_swizzle(struct drm_gem_object *obj)
+{
+	struct drm_device *dev = obj->dev;
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_i915_gem_object *obj_priv = obj->driver_private;
+	int page_count = obj->size >> PAGE_SHIFT;
+	int i;
+
+	if (dev_priv->mm.bit_6_swizzle_x != I915_BIT_6_SWIZZLE_9_10_17)
+		return;
+
+	if (obj_priv->bit_17 == NULL)
+		return;
+
+	for (i = 0; i < page_count; i++) {
+		char new_bit_17 = page_to_phys(obj_priv->pages[i]) >> 17;
+		if ((new_bit_17 & 0x1) !=
+		    (test_bit(i, obj_priv->bit_17) != 0)) {
+			int ret = i915_gem_swizzle_page(obj_priv->pages[i]);
+			if (ret != 0) {
+				DRM_ERROR("Failed to swizzle page\n");
+				return;
+			}
+			set_page_dirty(obj_priv->pages[i]);
+		}
+	}
+}
+
+void
+i915_gem_object_save_bit_17_swizzle(struct drm_gem_object *obj)
+{
+	struct drm_device *dev = obj->dev;
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_i915_gem_object *obj_priv = obj->driver_private;
+	int page_count = obj->size >> PAGE_SHIFT;
+	int i;
+
+	if (dev_priv->mm.bit_6_swizzle_x != I915_BIT_6_SWIZZLE_9_10_17)
+		return;
+
+	if (obj_priv->bit_17 == NULL) {
+		obj_priv->bit_17 = kmalloc(BITS_TO_LONGS(page_count) *
+					   sizeof(long), GFP_KERNEL);
+		if (obj_priv->bit_17 == NULL) {
+			DRM_ERROR("Failed to allocate memory for bit 17 "
+				  "record\n");
+			return;
+		}
+	}
+
+	for (i = 0; i < page_count; i++) {
+		if (page_to_phys(obj_priv->pages[i]) & (1 << 17))
+			__set_bit(i, obj_priv->bit_17);
+		else
+			__clear_bit(i, obj_priv->bit_17);
+	}
+}