#include <drm/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.
+/**
+ * DOC: buffer object tiling
*
- * 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.
+ * i915_gem_set_tiling() and i915_gem_get_tiling() is the userspace interface to
+ * declare fence register requirements.
*
- * If we don't have interleaved memory, all tiling is safe and no swizzling is
- * required.
+ * In principle GEM doesn't care at all about the internal data layout of an
+ * object, and hence it also doesn't care about tiling or swizzling. There's two
+ * exceptions:
*
- * 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!
+ * - For X and Y tiling the hardware provides detilers for CPU access, so called
+ * fences. Since there's only a limited amount of them the kernel must manage
+ * these, and therefore userspace must tell the kernel the object tiling if it
+ * wants to use fences for detiling.
+ * - On gen3 and gen4 platforms have a swizzling pattern for tiled objects which
+ * depends upon the physical page frame number. When swapping such objects the
+ * page frame number might change and the kernel must be able to fix this up
+ * and hence now the tiling. Note that on a subset of platforms with
+ * asymmetric memory channel population the swizzling pattern changes in an
+ * unknown way, and for those the kernel simply forbids swapping completely.
*
- * 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.
+ * Since neither of this applies for new tiling layouts on modern platforms like
+ * W, Ys and Yf tiling GEM only allows object tiling to be set to X or Y tiled.
+ * Anything else can be handled in userspace entirely without the kernel's
+ * invovlement.
*/
-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;
-}
/* Check pitch constriants for all chips & tiling formats */
static bool
}
/**
+ * i915_gem_set_tiling - IOCTL handler to set tiling mode
+ * @dev: DRM device
+ * @data: data pointer for the ioctl
+ * @file: DRM file for the ioctl call
+ *
* Sets the tiling mode of an object, returning the required swizzling of
* bit 6 of addresses in the object.
+ *
+ * Called by the user via ioctl.
+ *
+ * Returns:
+ * Zero on success, negative errno on failure.
*/
int
i915_gem_set_tiling(struct drm_device *dev, void *data,
}
mutex_lock(&dev->struct_mutex);
- if (i915_gem_obj_is_pinned(obj) || obj->framebuffer_references) {
+ if (obj->pin_display || obj->framebuffer_references) {
ret = -EBUSY;
goto err;
}
}
/**
+ * i915_gem_get_tiling - IOCTL handler to get tiling mode
+ * @dev: DRM device
+ * @data: data pointer for the ioctl
+ * @file: DRM file for the ioctl call
+ *
* Returns the current tiling mode and required bit 6 swizzling for the object.
+ *
+ * Called by the user via ioctl.
+ *
+ * Returns:
+ * Zero on success, negative errno on failure.
*/
int
i915_gem_get_tiling(struct drm_device *dev, void *data,
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)
-{
- 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++;
- }
-}
-
-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++;
- }
-}
Code Review / kvmfornfv.git / blobdiff