/* * Copyright © 2008-2015 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. */ #include #include #include "i915_drv.h" /** * DOC: fence register handling * * Important to avoid confusions: "fences" in the i915 driver are not execution * fences used to track command completion but hardware detiler objects which * wrap a given range of the global GTT. Each platform has only a fairly limited * set of these objects. * * Fences are used to detile GTT memory mappings. They're also connected to the * hardware frontbuffer render tracking and hence interract with frontbuffer * conmpression. Furthermore on older platforms fences are required for tiled * objects used by the display engine. They can also be used by the render * engine - they're required for blitter commands and are optional for render * commands. But on gen4+ both display (with the exception of fbc) and rendering * have their own tiling state bits and don't need fences. * * Also note that fences only support X and Y tiling and hence can't be used for * the fancier new tiling formats like W, Ys and Yf. * * Finally note that because fences are such a restricted resource they're * dynamically associated with objects. Furthermore fence state is committed to * the hardware lazily to avoid unecessary stalls on gen2/3. Therefore code must * explictly call i915_gem_object_get_fence() to synchronize fencing status * for cpu access. Also note that some code wants an unfenced view, for those * cases the fence can be removed forcefully with i915_gem_object_put_fence(). * * Internally these functions will synchronize with userspace access by removing * CPU ptes into GTT mmaps (not the GTT ptes themselves) as needed. */ static void i965_write_fence_reg(struct drm_device *dev, int reg, struct drm_i915_gem_object *obj) { struct drm_i915_private *dev_priv = dev->dev_private; int fence_reg; int fence_pitch_shift; if (INTEL_INFO(dev)->gen >= 6) { fence_reg = FENCE_REG_SANDYBRIDGE_0; fence_pitch_shift = SANDYBRIDGE_FENCE_PITCH_SHIFT; } else { fence_reg = FENCE_REG_965_0; fence_pitch_shift = I965_FENCE_PITCH_SHIFT; } fence_reg += reg * 8; /* To w/a incoherency with non-atomic 64-bit register updates, * we split the 64-bit update into two 32-bit writes. In order * for a partial fence not to be evaluated between writes, we * precede the update with write to turn off the fence register, * and only enable the fence as the last step. * * For extra levels of paranoia, we make sure each step lands * before applying the next step. */ I915_WRITE(fence_reg, 0); POSTING_READ(fence_reg); if (obj) { u32 size = i915_gem_obj_ggtt_size(obj); uint64_t val; /* Adjust fence size to match tiled area */ if (obj->tiling_mode != I915_TILING_NONE) { uint32_t row_size = obj->stride * (obj->tiling_mode == I915_TILING_Y ? 32 : 8); size = (size / row_size) * row_size; } val = (uint64_t)((i915_gem_obj_ggtt_offset(obj) + size - 4096) & 0xfffff000) << 32; val |= i915_gem_obj_ggtt_offset(obj) & 0xfffff000; val |= (uint64_t)((obj->stride / 128) - 1) << fence_pitch_shift; if (obj->tiling_mode == I915_TILING_Y) val |= 1 << I965_FENCE_TILING_Y_SHIFT; val |= I965_FENCE_REG_VALID; I915_WRITE(fence_reg + 4, val >> 32); POSTING_READ(fence_reg + 4); I915_WRITE(fence_reg + 0, val); POSTING_READ(fence_reg); } else { I915_WRITE(fence_reg + 4, 0); POSTING_READ(fence_reg + 4); } } static void i915_write_fence_reg(struct drm_device *dev, int reg, struct drm_i915_gem_object *obj) { struct drm_i915_private *dev_priv = dev->dev_private; u32 val; if (obj) { u32 size = i915_gem_obj_ggtt_size(obj); int pitch_val; int tile_width; WARN((i915_gem_obj_ggtt_offset(obj) & ~I915_FENCE_START_MASK) || (size & -size) != size || (i915_gem_obj_ggtt_offset(obj) & (size - 1)), "object 0x%08lx [fenceable? %d] not 1M or pot-size (0x%08x) aligned\n", i915_gem_obj_ggtt_offset(obj), obj->map_and_fenceable, size); if (obj->tiling_mode == I915_TILING_Y && HAS_128_BYTE_Y_TILING(dev)) tile_width = 128; else tile_width = 512; /* Note: pitch better be a power of two tile widths */ pitch_val = obj->stride / tile_width; pitch_val = ffs(pitch_val) - 1; val = i915_gem_obj_ggtt_offset(obj); if (obj->tiling_mode == I915_TILING_Y) val |= 1 << I830_FENCE_TILING_Y_SHIFT; val |= I915_FENCE_SIZE_BITS(size); val |= pitch_val << I830_FENCE_PITCH_SHIFT; val |= I830_FENCE_REG_VALID; } else val = 0; if (reg < 8) reg = FENCE_REG_830_0 + reg * 4; else reg = FENCE_REG_945_8 + (reg - 8) * 4; I915_WRITE(reg, val); POSTING_READ(reg); } static void i830_write_fence_reg(struct drm_device *dev, int reg, struct drm_i915_gem_object *obj) { struct drm_i915_private *dev_priv = dev->dev_private; uint32_t val; if (obj) { u32 size = i915_gem_obj_ggtt_size(obj); uint32_t pitch_val; WARN((i915_gem_obj_ggtt_offset(obj) & ~I830_FENCE_START_MASK) || (size & -size) != size || (i915_gem_obj_ggtt_offset(obj) & (size - 1)), "object 0x%08lx not 512K or pot-size 0x%08x aligned\n", i915_gem_obj_ggtt_offset(obj), size); pitch_val = obj->stride / 128; pitch_val = ffs(pitch_val) - 1; val = i915_gem_obj_ggtt_offset(obj); if (obj->tiling_mode == I915_TILING_Y) val |= 1 << I830_FENCE_TILING_Y_SHIFT; val |= I830_FENCE_SIZE_BITS(size); val |= pitch_val << I830_FENCE_PITCH_SHIFT; val |= I830_FENCE_REG_VALID; } else val = 0; I915_WRITE(FENCE_REG_830_0 + reg * 4, val); POSTING_READ(FENCE_REG_830_0 + reg * 4); } inline static bool i915_gem_object_needs_mb(struct drm_i915_gem_object *obj) { return obj && obj->base.read_domains & I915_GEM_DOMAIN_GTT; } static void i915_gem_write_fence(struct drm_device *dev, int reg, struct drm_i915_gem_object *obj) { struct drm_i915_private *dev_priv = dev->dev_private; /* Ensure that all CPU reads are completed before installing a fence * and all writes before removing the fence. */ if (i915_gem_object_needs_mb(dev_priv->fence_regs[reg].obj)) mb(); WARN(obj && (!obj->stride || !obj->tiling_mode), "bogus fence setup with stride: 0x%x, tiling mode: %i\n", obj->stride, obj->tiling_mode); if (IS_GEN2(dev)) i830_write_fence_reg(dev, reg, obj); else if (IS_GEN3(dev)) i915_write_fence_reg(dev, reg, obj); else if (INTEL_INFO(dev)->gen >= 4) i965_write_fence_reg(dev, reg, obj); /* And similarly be paranoid that no direct access to this region * is reordered to before the fence is installed. */ if (i915_gem_object_needs_mb(obj)) mb(); } static inline int fence_number(struct drm_i915_private *dev_priv, struct drm_i915_fence_reg *fence) { return fence - dev_priv->fence_regs; } static void i915_gem_object_update_fence(struct drm_i915_gem_object *obj, struct drm_i915_fence_reg *fence, bool enable) { struct drm_i915_private *dev_priv = obj->base.dev->dev_private; int reg = fence_number(dev_priv, fence); i915_gem_write_fence(obj->base.dev, reg, enable ? obj : NULL); if (enable) { obj->fence_reg = reg; fence->obj = obj; list_move_tail(&fence->lru_list, &dev_priv->mm.fence_list); } else { obj->fence_reg = I915_FENCE_REG_NONE; fence->obj = NULL; list_del_init(&fence->lru_list); } obj->fence_dirty = false; } static inline void i915_gem_object_fence_lost(struct drm_i915_gem_object *obj) { if (obj->tiling_mode) i915_gem_release_mmap(obj); /* As we do not have an associated fence register, we will force * a tiling change if we ever need to acquire one. */ obj->fence_dirty = false; obj->fence_reg = I915_FENCE_REG_NONE; } static int i915_gem_object_wait_fence(struct drm_i915_gem_object *obj) { if (obj->last_fenced_req) { int ret = i915_wait_request(obj->last_fenced_req); if (ret) return ret; i915_gem_request_assign(&obj->last_fenced_req, NULL); } return 0; } /** * i915_gem_object_put_fence - force-remove fence for an object * @obj: object to map through a fence reg * * This function force-removes any fence from the given object, which is useful * if the kernel wants to do untiled GTT access. * * Returns: * * 0 on success, negative error code on failure. */ int i915_gem_object_put_fence(struct drm_i915_gem_object *obj) { struct drm_i915_private *dev_priv = obj->base.dev->dev_private; struct drm_i915_fence_reg *fence; int ret; ret = i915_gem_object_wait_fence(obj); if (ret) return ret; if (obj->fence_reg == I915_FENCE_REG_NONE) return 0; fence = &dev_priv->fence_regs[obj->fence_reg]; if (WARN_ON(fence->pin_count)) return -EBUSY; i915_gem_object_fence_lost(obj); i915_gem_object_update_fence(obj, fence, false); return 0; } static struct drm_i915_fence_reg * i915_find_fence_reg(struct drm_device *dev) { struct drm_i915_private *dev_priv = dev->dev_private; struct drm_i915_fence_reg *reg, *avail; int i; /* First try to find a free reg */ avail = NULL; for (i = dev_priv->fence_reg_start; i < dev_priv->num_fence_regs; i++) { reg = &dev_priv->fence_regs[i]; if (!reg->obj) return reg; if (!reg->pin_count) avail = reg; } if (avail == NULL) goto deadlock; /* None available, try to steal one or wait for a user to finish */ list_for_each_entry(reg, &dev_priv->mm.fence_list, lru_list) { if (reg->pin_count) continue; return reg; } deadlock: /* Wait for completion of pending flips which consume fences */ if (intel_has_pending_fb_unpin(dev)) return ERR_PTR(-EAGAIN); return ERR_PTR(-EDEADLK); } /** * i915_gem_object_get_fence - set up fencing for an object * @obj: object to map through a fence reg * * When mapping objects through the GTT, userspace wants to be able to write * to them without having to worry about swizzling if the object is tiled. * This function walks the fence regs looking for a free one for @obj, * stealing one if it can't find any. * * It then sets up the reg based on the object's properties: address, pitch * and tiling format. * * For an untiled surface, this removes any existing fence. * * Returns: * * 0 on success, negative error code on failure. */ int i915_gem_object_get_fence(struct drm_i915_gem_object *obj) { struct drm_device *dev = obj->base.dev; struct drm_i915_private *dev_priv = dev->dev_private; bool enable = obj->tiling_mode != I915_TILING_NONE; struct drm_i915_fence_reg *reg; int ret; /* Have we updated the tiling parameters upon the object and so * will need to serialise the write to the associated fence register? */ if (obj->fence_dirty) { ret = i915_gem_object_wait_fence(obj); if (ret) return ret; } /* Just update our place in the LRU if our fence is getting reused. */ if (obj->fence_reg != I915_FENCE_REG_NONE) { reg = &dev_priv->fence_regs[obj->fence_reg]; if (!obj->fence_dirty) { list_move_tail(®->lru_list, &dev_priv->mm.fence_list); return 0; } } else if (enable) { if (WARN_ON(!obj->map_and_fenceable)) return -EINVAL; reg = i915_find_fence_reg(dev); if (IS_ERR(reg)) return PTR_ERR(reg); if (reg->obj) { struct drm_i915_gem_object *old = reg->obj; ret = i915_gem_object_wait_fence(old); if (ret) return ret; i915_gem_object_fence_lost(old); } } else return 0; i915_gem_object_update_fence(obj, reg, enable); return 0; } /** * i915_gem_object_pin_fence - pin fencing state * @obj: object to pin fencing for * * This pins the fencing state (whether tiled or untiled) to make sure the * object is ready to be used as a scanout target. Fencing status must be * synchronize first by calling i915_gem_object_get_fence(): * * The resulting fence pin reference must be released again with * i915_gem_object_unpin_fence(). * * Returns: * * True if the object has a fence, false otherwise. */ bool i915_gem_object_pin_fence(struct drm_i915_gem_object *obj) { if (obj->fence_reg != I915_FENCE_REG_NONE) { struct drm_i915_private *dev_priv = obj->base.dev->dev_private; struct i915_vma *ggtt_vma = i915_gem_obj_to_ggtt(obj); WARN_ON(!ggtt_vma || dev_priv->fence_regs[obj->fence_reg].pin_count > ggtt_vma->pin_count); dev_priv->fence_regs[obj->fence_reg].pin_count++; return true; } else return false; } /** * i915_gem_object_unpin_fence - unpin fencing state * @obj: object to unpin fencing for * * This releases the fence pin reference acquired through * i915_gem_object_pin_fence. It will handle both objects with and without an * attached fence correctly, callers do not need to distinguish this. */ void i915_gem_object_unpin_fence(struct drm_i915_gem_object *obj) { if (obj->fence_reg != I915_FENCE_REG_NONE) { struct drm_i915_private *dev_priv = obj->base.dev->dev_private; WARN_ON(dev_priv->fence_regs[obj->fence_reg].pin_count <= 0); dev_priv->fence_regs[obj->fence_reg].pin_count--; } } /** * i915_gem_restore_fences - restore fence state * @dev: DRM device * * Restore the hw fence state to match the software tracking again, to be called * after a gpu reset and on resume. */ void i915_gem_restore_fences(struct drm_device *dev) { struct drm_i915_private *dev_priv = dev->dev_private; int i; for (i = 0; i < dev_priv->num_fence_regs; i++) { struct drm_i915_fence_reg *reg = &dev_priv->fence_regs[i]; /* * Commit delayed tiling changes if we have an object still * attached to the fence, otherwise just clear the fence. */ if (reg->obj) { i915_gem_object_update_fence(reg->obj, reg, reg->obj->tiling_mode); } else { i915_gem_write_fence(dev, i, NULL); } } } /** * DOC: tiling swizzling details * * 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. */ /** * i915_gem_detect_bit_6_swizzle - detect bit 6 swizzling pattern * @dev: DRM device * * 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) { struct drm_i915_private *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 >= 8 || IS_VALLEYVIEW(dev)) { /* * On BDW+, swizzling is not used. We leave the CPU memory * controller in charge of optimizing memory accesses without * the extra address manipulation GPU side. * * VLV and CHV don't have GPU swizzling. */ swizzle_x = I915_BIT_6_SWIZZLE_NONE; swizzle_y = I915_BIT_6_SWIZZLE_NONE; } else if (INTEL_INFO(dev)->gen >= 6) { if (dev_priv->preserve_bios_swizzle) { if (I915_READ(DISP_ARB_CTL) & DISP_TILE_SURFACE_SWIZZLING) { 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 { 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; } /* check for L-shaped memory aka modified enhanced addressing */ if (IS_GEN4(dev)) { uint32_t ddc2 = I915_READ(DCC2); if (!(ddc2 & DCC2_MODIFIED_ENHANCED_DISABLE)) dev_priv->quirks |= QUIRK_PIN_SWIZZLED_PAGES; } 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; } /* * 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); } /** * i915_gem_object_do_bit_17_swizzle - fixup bit 17 swizzling * @obj: i915 GEM buffer object * * This function fixes up the swizzling in case any page frame number for this * object has changed in bit 17 since that state has been saved with * i915_gem_object_save_bit_17_swizzle(). * * This is called when pinning backing storage again, since the kernel is free * to move unpinned backing storage around (either by directly moving pages or * by swapping them out and back in again). */ void i915_gem_object_do_bit_17_swizzle(struct drm_i915_gem_object *obj) { struct sg_page_iter sg_iter; int i; if (obj->bit_17 == NULL) return; i = 0; for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0) { struct page *page = sg_page_iter_page(&sg_iter); char new_bit_17 = page_to_phys(page) >> 17; if ((new_bit_17 & 0x1) != (test_bit(i, obj->bit_17) != 0)) { i915_gem_swizzle_page(page); set_page_dirty(page); } i++; } } /** * i915_gem_object_save_bit_17_swizzle - save bit 17 swizzling * @obj: i915 GEM buffer object * * This function saves the bit 17 of each page frame number so that swizzling * can be fixed up later on with i915_gem_object_do_bit_17_swizzle(). This must * be called before the backing storage can be unpinned. */ void i915_gem_object_save_bit_17_swizzle(struct drm_i915_gem_object *obj) { struct sg_page_iter sg_iter; int page_count = obj->base.size >> PAGE_SHIFT; int i; if (obj->bit_17 == NULL) { obj->bit_17 = kcalloc(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; } } i = 0; for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents, 0) { if (page_to_phys(sg_page_iter_page(&sg_iter)) & (1 << 17)) __set_bit(i, obj->bit_17); else __clear_bit(i, obj->bit_17); i++; } }