/* * 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 * */ #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; uint32_t swizzle_x = I915_BIT_6_SWIZZLE_UNKNOWN; uint32_t swizzle_y = I915_BIT_6_SWIZZLE_UNKNOWN; if (!IS_I9XX(dev)) { /* 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; } else if ((!IS_I965G(dev) && !IS_G33(dev)) || IS_I965GM(dev) || IS_GM45(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 = I915_READ(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) || IS_GM45(dev)) && (dcc & DCC_CHANNEL_XOR_BIT_17) == 0) { /* GM965/GM45 does either bit 11 or bit 17 * swizzling. */ 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 { /* The 965, G33, and newer, have a very flexible memory * configuration. It will enable dual-channel mode * (interleaving) on as much memory as it can, and the GPU * will additionally sometimes enable different bit 6 * swizzling for tiled objects from the CPU. * * Here's what I found on the G965: * slot fill memory size swizzling * 0A 0B 1A 1B 1-ch 2-ch * 512 0 0 0 512 0 O * 512 0 512 0 16 1008 X * 512 0 0 512 16 1008 X * 0 512 0 512 16 1008 X * 1024 1024 1024 0 2048 1024 O * * We could probably detect this based on either the DRB * matching, which was the case for the swizzling required in * the table above, or from the 1-ch value being less than * the minimum size of a rank. */ if (I915_READ16(C0DRB3) != I915_READ16(C1DRB3)) { 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; } } 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; obj_priv->stride = args->stride; 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; }