/* * 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 "linux/string.h" #include "linux/bitops.h" #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 (INTEL_INFO(dev)->gen >= 6) { uint32_t dimm_c0, dimm_c1; dimm_c0 = I915_READ(MAD_DIMM_C0); dimm_c1 = I915_READ(MAD_DIMM_C1); dimm_c0 &= MAD_DIMM_A_SIZE_MASK | MAD_DIMM_B_SIZE_MASK; dimm_c1 &= MAD_DIMM_A_SIZE_MASK | MAD_DIMM_B_SIZE_MASK; /* Enable swizzling when the channels are populated with * identically sized dimms. We don't need to check the 3rd * channel because no cpu with gpu attached ships in that * configuration. Also, swizzling only makes sense for 2 * channels anyway. */ if (dimm_c0 == dimm_c1) { swizzle_x = I915_BIT_6_SWIZZLE_9_10; swizzle_y = I915_BIT_6_SWIZZLE_9; } else { swizzle_x = I915_BIT_6_SWIZZLE_NONE; swizzle_y = I915_BIT_6_SWIZZLE_NONE; } } else if (IS_GEN5(dev)) { /* On Ironlake whatever DRAM config, GPU always do * same swizzling setup. */ swizzle_x = I915_BIT_6_SWIZZLE_9_10; swizzle_y = I915_BIT_6_SWIZZLE_9; } else if (IS_GEN2(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_MOBILE(dev) || (IS_GEN3(dev) && !IS_G33(dev))) { uint32_t dcc; /* On 9xx chipsets, channel interleave by the CPU is * determined by DCC. For single-channel, neither the CPU * nor the GPU do swizzling. For dual channel interleaved, * the GPU's interleave is bit 9 and 10 for X tiled, and bit * 9 for Y tiled. The CPU's interleave is independent, and * can be based on either bit 11 (haven't seen this yet) or * bit 17 (common). */ 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 (dcc & DCC_CHANNEL_XOR_DISABLE) { /* This is the base swizzling by the GPU for * tiled buffers. */ swizzle_x = I915_BIT_6_SWIZZLE_9_10; swizzle_y = I915_BIT_6_SWIZZLE_9; } else if ((dcc & DCC_CHANNEL_XOR_BIT_17) == 0) { /* Bit 11 swizzling by the CPU in addition. */ swizzle_x = I915_BIT_6_SWIZZLE_9_10_11; swizzle_y = I915_BIT_6_SWIZZLE_9_11; } else { /* Bit 17 swizzling by the CPU in addition. */ swizzle_x = I915_BIT_6_SWIZZLE_9_10_17; swizzle_y = I915_BIT_6_SWIZZLE_9_17; } 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; } /* Check pitch constriants for all chips & tiling formats */ static bool i915_tiling_ok(struct drm_device *dev, int stride, int size, int tiling_mode) { int tile_width; /* Linear is always fine */ if (tiling_mode == I915_TILING_NONE) return true; if (IS_GEN2(dev) || (tiling_mode == I915_TILING_Y && HAS_128_BYTE_Y_TILING(dev))) tile_width = 128; else tile_width = 512; /* check maximum stride & object size */ if (INTEL_INFO(dev)->gen >= 4) { /* i965 stores the end address of the gtt mapping in the fence * reg, so dont bother to check the size */ if (stride / 128 > I965_FENCE_MAX_PITCH_VAL) return false; } else { if (stride > 8192) return false; if (IS_GEN3(dev)) { if (size > I830_FENCE_MAX_SIZE_VAL << 20) return false; } else { if (size > I830_FENCE_MAX_SIZE_VAL << 19) return false; } } /* 965+ just needs multiples of tile width */ if (INTEL_INFO(dev)->gen >= 4) { if (stride & (tile_width - 1)) return false; return true; } /* Pre-965 needs power of two tile widths */ if (stride < tile_width) return false; if (stride & (stride - 1)) return false; return true; } /* Is the current GTT allocation valid for the change in tiling? */ static bool i915_gem_object_fence_ok(struct drm_i915_gem_object *obj, int tiling_mode) { u32 size; if (tiling_mode == I915_TILING_NONE) return true; if (INTEL_INFO(obj->base.dev)->gen >= 4) return true; if (INTEL_INFO(obj->base.dev)->gen == 3) { if (obj->gtt_offset & ~I915_FENCE_START_MASK) return false; } else { if (obj->gtt_offset & ~I830_FENCE_START_MASK) return false; } /* * Previous chips need to be aligned to the size of the smallest * fence register that can contain the object. */ if (INTEL_INFO(obj->base.dev)->gen == 3) size = 1024*1024; else size = 512*1024; while (size < obj->base.size) size <<= 1; if (obj->gtt_space->size != size) return false; if (obj->gtt_offset & (size - 1)) return false; return true; } /** * 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) { struct drm_i915_gem_set_tiling *args = data; drm_i915_private_t *dev_priv = dev->dev_private; struct drm_i915_gem_object *obj; int ret = 0; obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle)); if (&obj->base == NULL) return -ENOENT; if (!i915_tiling_ok(dev, args->stride, obj->base.size, args->tiling_mode)) { drm_gem_object_unreference_unlocked(&obj->base); return -EINVAL; } if (obj->pin_count) { drm_gem_object_unreference_unlocked(&obj->base); return -EBUSY; } if (args->tiling_mode == I915_TILING_NONE) { args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE; args->stride = 0; } 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; /* 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; args->swizzle_mode = I915_BIT_6_SWIZZLE_NONE; args->stride = 0; } } mutex_lock(&dev->struct_mutex); if (args->tiling_mode != obj->tiling_mode || args->stride != obj->stride) { /* We need to rebind the object if its current allocation * no longer meets the alignment restrictions for its new * tiling mode. Otherwise we can just leave it alone, but * need to ensure that any fence register is cleared. * * After updating the tiling parameters, we then flag whether * we need to update an associated fence register. Note this * has to also include the unfenced register the GPU uses * whilst executing a fenced command for an untiled object. */ i915_gem_release_mmap(obj); obj->map_and_fenceable = obj->gtt_space == NULL || (obj->gtt_offset + obj->base.size <= dev_priv->mm.gtt_mappable_end && i915_gem_object_fence_ok(obj, args->tiling_mode)); /* Rebind if we need a change of alignment */ if (!obj->map_and_fenceable) { u32 unfenced_alignment = i915_gem_get_unfenced_gtt_alignment(dev, obj->base.size, args->tiling_mode); if (obj->gtt_offset & (unfenced_alignment - 1)) ret = i915_gem_object_unbind(obj); } if (ret == 0) { obj->fence_dirty = obj->fenced_gpu_access || obj->fence_reg != I915_FENCE_REG_NONE; obj->tiling_mode = args->tiling_mode; obj->stride = args->stride; } } /* we have to maintain this existing ABI... */ args->stride = obj->stride; args->tiling_mode = obj->tiling_mode; drm_gem_object_unreference(&obj->base); mutex_unlock(&dev->struct_mutex); return ret; } /** * 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) { struct drm_i915_gem_get_tiling *args = data; drm_i915_private_t *dev_priv = dev->dev_private; struct drm_i915_gem_object *obj; obj = to_intel_bo(drm_gem_object_lookup(dev, file, args->handle)); if (&obj->base == NULL) return -ENOENT; mutex_lock(&dev->struct_mutex); args->tiling_mode = obj->tiling_mode; switch (obj->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"); } /* 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->base); 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 void i915_gem_swizzle_page(struct page *page) { char temp[64]; char *vaddr; int i; vaddr = kmap(page); 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); } void i915_gem_object_do_bit_17_swizzle(struct drm_i915_gem_object *obj) { int page_count = obj->base.size >> PAGE_SHIFT; int i; if (obj->bit_17 == NULL) return; for (i = 0; i < page_count; i++) { char new_bit_17 = page_to_phys(obj->pages[i]) >> 17; if ((new_bit_17 & 0x1) != (test_bit(i, obj->bit_17) != 0)) { i915_gem_swizzle_page(obj->pages[i]); set_page_dirty(obj->pages[i]); } } } void i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object *obj) { int page_count = obj->base.size >> PAGE_SHIFT; int i; if (obj->bit_17 == NULL) { obj->bit_17 = kmalloc(BITS_TO_LONGS(page_count) * sizeof(long), GFP_KERNEL); if (obj->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->pages[i]) & (1 << 17)) __set_bit(i, obj->bit_17); else __clear_bit(i, obj->bit_17); } }