1 files changed, 309 insertions, 0 deletions
diff --git a/linux-core/i915_gem_tiling.c b/linux-core/i915_gem_tiling.c
new file mode 100644
index 00000000..a4ff736f
--- /dev/null
+++ b/linux-core/i915_gem_tiling.c
@@ -0,0 +1,309 @@
+/*
+ * Copyright © 2008 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Authors:
+ *    Eric Anholt <eric@anholt.net>
+ *
+ */
+
+#include "drmP.h"
+#include "drm.h"
+#include "i915_drm.h"
+#include "i915_drv.h"
+
+/** @file i915_gem_tiling.c
+ *
+ * Support for managing tiling state of buffer objects.
+ *
+ * The idea behind tiling is to increase cache hit rates by rearranging
+ * pixel data so that a group of pixel accesses are in the same cacheline.
+ * Performance improvement from doing this on the back/depth buffer are on
+ * the order of 30%.
+ *
+ * Intel architectures make this somewhat more complicated, though, by
+ * adjustments made to addressing of data when the memory is in interleaved
+ * mode (matched pairs of DIMMS) to improve memory bandwidth.
+ * For interleaved memory, the CPU sends every sequential 64 bytes
+ * to an alternate memory channel so it can get the bandwidth from both.
+ *
+ * The GPU also rearranges its accesses for increased bandwidth to interleaved
+ * memory, and it matches what the CPU does for non-tiled.  However, when tiled
+ * it does it a little differently, since one walks addresses not just in the
+ * X direction but also Y.  So, along with alternating channels when bit
+ * 6 of the address flips, it also alternates when other bits flip --  Bits 9
+ * (every 512 bytes, an X tile scanline) and 10 (every two X tile scanlines)
+ * are common to both the 915 and 965-class hardware.
+ *
+ * The CPU also sometimes XORs in higher bits as well, to improve
+ * bandwidth doing strided access like we do so frequently in graphics.  This
+ * is called "Channel XOR Randomization" in the MCH documentation.  The result
+ * is that the CPU is XORing in either bit 11 or bit 17 to bit 6 of its address
+ * decode.
+ *
+ * All of this bit 6 XORing has an effect on our memory management,
+ * as we need to make sure that the 3d driver can correctly address object
+ * contents.
+ *
+ * If we don't have interleaved memory, all tiling is safe and no swizzling is
+ * required.
+ *
+ * When bit 17 is XORed in, we simply refuse to tile at all.  Bit
+ * 17 is not just a page offset, so as we page an objet out and back in,
+ * individual pages in it will have different bit 17 addresses, resulting in
+ * each 64 bytes being swapped with its neighbor!
+ *
+ * Otherwise, if interleaved, we have to tell the 3d driver what the address
+ * swizzling it needs to do is, since it's writing with the CPU to the pages
+ * (bit 6 and potentially bit 11 XORed in), and the GPU is reading from the
+ * pages (bit 6, 9, and 10 XORed in), resulting in a cumulative bit swizzling
+ * required by the CPU of XORing in bit 6, 9, 10, and potentially 11, in order
+ * to match what the GPU expects.
+ */
+
+/**
+ * Detects bit 6 swizzling of address lookup between IGD access and CPU
+ * access through main memory.
+ */
+void
+i915_gem_detect_bit_6_swizzle(struct drm_device *dev)
+{
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct pci_dev *bridge;
+	uint32_t swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN;
+	uint32_t swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;
+	int mchbar_offset;
+	char __iomem *mchbar;
+	int ret;
+
+	bridge = pci_get_bus_and_slot(0, PCI_DEVFN(0, 0));
+	if (bridge == NULL) {
+		DRM_ERROR("Couldn't get bridge device\n");
+		return;
+	}
+
+	ret = pci_enable_device(bridge);
+	if (ret != 0) {
+		DRM_ERROR("pci_enable_device failed: %d\n", ret);
+		return;
+	}
+
+	if (IS_I965G(dev))
+		mchbar_offset = 0x48;
+	else
+		mchbar_offset = 0x44;
+
+	/* Use resource 2 for our BAR that's stashed in a nonstandard location,
+	 * since the bridge would only ever use standard BARs 0-1 (though it
+	 * doesn't anyway)
+	 */
+	ret = pci_read_base(bridge, mchbar_offset, &bridge->resource[2]);
+	if (ret != 0) {
+		DRM_ERROR("pci_read_base failed: %d\n", ret);
+		return;
+	}
+
+	mchbar = ioremap(pci_resource_start(bridge, 2),
+			 pci_resource_len(bridge, 2));
+	if (mchbar == NULL) {
+		DRM_ERROR("Couldn't map MCHBAR to determine tile swizzling\n");
+		return;
+	}
+
+	if (IS_I965G(dev) && !IS_I965GM(dev)) {
+		uint32_t chdecmisc;
+
+		/* On the 965, channel interleave appears to be determined by
+		 * the flex bit.  If flex is set, then the ranks (sides of a
+		 * DIMM) of memory will be "stacked" (physical addresses walk
+		 * through one rank then move on to the next, flipping channels
+		 * or not depending on rank configuration).  The GPU in this
+		 * case does exactly the same addressing as the CPU.
+		 *
+		 * Unlike the 945, channel randomization based does not
+		 * appear to be available.
+		 *
+		 * XXX: While the G965 doesn't appear to do any interleaving
+		 * when the DIMMs are not exactly matched, the G4x chipsets
+		 * might be for "L-shaped" configurations, and will need to be
+		 * detected.
+		 *
+		 * L-shaped configuration:
+		 *
+		 * +-----+
+		 * |     |
+		 * |DIMM2|         <-- non-interleaved
+		 * +-----+
+		 * +-----+ +-----+
+		 * |     | |     |
+		 * |DIMM0| |DIMM1| <-- interleaved area
+		 * +-----+ +-----+
+		 */
+		chdecmisc = readb(mchbar + CHDECMISC);
+
+		if (chdecmisc == 0xff) {
+			DRM_ERROR("Couldn't read from MCHBAR.  "
+				  "Disabling tiling.\n");
+		} else if (chdecmisc & CHDECMISC_FLEXMEMORY) {
+			swizzle_x = I915_BIT_6_SWIZZLE_NONE;
+			swizzle_y = I915_BIT_6_SWIZZLE_NONE;
+		} else {
+			swizzle_x = I915_BIT_6_SWIZZLE_9_10;
+			swizzle_y = I915_BIT_6_SWIZZLE_9;
+		}
+	} else if (IS_I9XX(dev)) {
+		uint32_t dcc;
+
+		/* On 915-945 and GM965, channel interleave by the CPU is
+		 * determined by DCC.  The CPU will alternate based on bit 6
+		 * in interleaved mode, and the GPU will then also alternate
+		 * on bit 6, 9, and 10 for X, but the CPU may also optionally
+		 * alternate based on bit 17 (XOR not disabled and XOR
+		 * bit == 17).
+		 */
+		dcc = readl(mchbar + DCC);
+		switch (dcc & DCC_ADDRESSING_MODE_MASK) {
+		case DCC_ADDRESSING_MODE_SINGLE_CHANNEL:
+		case DCC_ADDRESSING_MODE_DUAL_CHANNEL_ASYMMETRIC:
+			swizzle_x = I915_BIT_6_SWIZZLE_NONE;
+			swizzle_y = I915_BIT_6_SWIZZLE_NONE;
+			break;
+		case DCC_ADDRESSING_MODE_DUAL_CHANNEL_INTERLEAVED:
+			if (IS_I915G(dev) || IS_I915GM(dev) ||
+			    dcc & DCC_CHANNEL_XOR_DISABLE) {
+				swizzle_x = I915_BIT_6_SWIZZLE_9_10;
+				swizzle_y = I915_BIT_6_SWIZZLE_9;
+			} else if (IS_I965GM(dev)) {
+				/* GM965 only does bit 11-based channel
+				 * randomization
+				 */
+				swizzle_x = I915_BIT_6_SWIZZLE_9_10_11;
+				swizzle_y = I915_BIT_6_SWIZZLE_9_11;
+			} else {
+				/* Bit 17 or perhaps other swizzling */
+				swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN;
+				swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;
+			}
+			break;
+		}
+		if (dcc == 0xffffffff) {
+			DRM_ERROR("Couldn't read from MCHBAR.  "
+				  "Disabling tiling.\n");
+			swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN;
+			swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN;
+		}
+	} else {
+		/* As far as we know, the 865 doesn't have these bit 6
+		 * swizzling issues.
+		 */
+		swizzle_x = I915_BIT_6_SWIZZLE_NONE;
+		swizzle_y = I915_BIT_6_SWIZZLE_NONE;
+	}
+
+	iounmap(mchbar);
+
+	dev_priv->mm.bit_6_swizzle_x = swizzle_x;
+	dev_priv->mm.bit_6_swizzle_y = swizzle_y;
+}
+
+/**
+ * Sets the tiling mode of an object, returning the required swizzling of
+ * bit 6 of addresses in the object.
+ */
+int
+i915_gem_set_tiling(struct drm_device *dev, void *data,
+		   struct drm_file *file_priv)
+{
+	struct drm_i915_gem_set_tiling *args = data;
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_gem_object *obj;
+	struct drm_i915_gem_object *obj_priv;
+
+	obj = drm_gem_object_lookup(dev, file_priv, args->handle);
+	if (obj == NULL)
+		return -EINVAL;
+	obj_priv = obj->driver_private;
+
+	mutex_lock(&dev->struct_mutex);
+
+	if (args->tiling_mode == I915_TILING_NONE) {
+		obj_priv->tiling_mode = I915_TILING_NONE;
+		args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
+	} else {
+		if (args->tiling_mode == I915_TILING_X)
+			args->swizzle_mode = dev_priv->mm.bit_6_swizzle_x;
+		else
+			args->swizzle_mode = dev_priv->mm.bit_6_swizzle_y;
+		/* 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;
+			args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
+		}
+	}
+	obj_priv->tiling_mode = args->tiling_mode;
+
+	mutex_unlock(&dev->struct_mutex);
+
+	drm_gem_object_unreference(obj);
+
+	return 0;
+}
+
+/**
+ * Returns the current tiling mode and required bit 6 swizzling for the object.
+ */
+int
+i915_gem_get_tiling(struct drm_device *dev, void *data,
+		   struct drm_file *file_priv)
+{
+	struct drm_i915_gem_get_tiling *args = data;
+	drm_i915_private_t *dev_priv = dev->dev_private;
+	struct drm_gem_object *obj;
+	struct drm_i915_gem_object *obj_priv;
+
+	obj = drm_gem_object_lookup(dev, file_priv, args->handle);
+	if (obj == NULL)
+		return -EINVAL;
+	obj_priv = obj->driver_private;
+
+	mutex_lock(&dev->struct_mutex);
+
+	args->tiling_mode = obj_priv->tiling_mode;
+	switch (obj_priv->tiling_mode) {
+	case I915_TILING_X:
+		args->swizzle_mode = dev_priv->mm.bit_6_swizzle_x;
+		break;
+	case I915_TILING_Y:
+		args->swizzle_mode = dev_priv->mm.bit_6_swizzle_y;
+		break;
+	case I915_TILING_NONE:
+		args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE;
+		break;
+	default:
+		DRM_ERROR("unknown tiling mode\n");
+	}
+
+	mutex_unlock(&dev->struct_mutex);
+
+	drm_gem_object_unreference(obj);
+
+	return 0;
+}