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iris: Delete GTT mapping support

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In the bad old days, i965 used GTT mapping for detiling maps.  iris
never has, however.  The only reason it used GTT maps was in weird
fallback cases for dealing with BO imports from foreign memory.  We
now do staging blits for those, and never mmap them.

There are no more users of GTT mapping, so we can delete it.

Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/10941>
This commit is contained in:
Kenneth Graunke 2021-05-20 02:22:51 -07:00 • committed by Marge Bot
parent 2f30cf4ac9
commit 22bfb5355f
2 changed files with 0 additions and 87 deletions
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85
src/gallium/drivers/iris/iris_bufmgr.c
View file

@ -818,11 +818,6 @@ bo_free(struct iris_bo *bo)
os_munmap(bo->map_wc, bo->size);
bo->map_wc = NULL;
}
if (bo->map_gtt) {
VG_NOACCESS(bo->map_gtt, bo->size);
os_munmap(bo->map_gtt, bo->size);
bo->map_gtt = NULL;
}
if (bo->idle) {
bo_close(bo);
@ -1106,86 +1101,6 @@ iris_bo_map_wc(struct pipe_debug_callback *dbg,
return bo->map_wc;
}
/**
* Perform an uncached mapping via the GTT.
*
* Write access through the GTT is not quite fully coherent. On low power
* systems especially, like modern Atoms, we can observe reads from RAM before
* the write via GTT has landed. A write memory barrier that flushes the Write
* Combining Buffer (i.e. sfence/mfence) is not sufficient to order the later
* read after the write as the GTT write suffers a small delay through the GTT
* indirection. The kernel uses an uncached mmio read to ensure the GTT write
* is ordered with reads (either by the GPU, WB or WC) and unconditionally
* flushes prior to execbuf submission. However, if we are not informing the
* kernel about our GTT writes, it will not flush before earlier access, such
* as when using the cmdparser. Similarly, we need to be careful if we should
* ever issue a CPU read immediately following a GTT write.
*
* Telling the kernel about write access also has one more important
* side-effect. Upon receiving notification about the write, it cancels any
* scanout buffering for FBC/PSR and friends. Later FBC/PSR is then flushed by
* either SW_FINISH or DIRTYFB. The presumption is that we never write to the
* actual scanout via a mmaping, only to a backbuffer and so all the FBC/PSR
* tracking is handled on the buffer exchange instead.
*/
static void *
iris_bo_map_gtt(struct pipe_debug_callback *dbg,
struct iris_bo *bo, unsigned flags)
{
struct iris_bufmgr *bufmgr = bo->bufmgr;
/* If we don't support get/set_tiling, there's no support for GTT mapping
* either (it won't do any de-tiling for us).
*/
assert(bufmgr->has_tiling_uapi);
/* Get a mapping of the buffer if we haven't before. */
if (bo->map_gtt == NULL) {
DBG("bo_map_gtt: mmap %d (%s)\n", bo->gem_handle, bo->name);
struct drm_i915_gem_mmap_gtt mmap_arg = { .handle = bo->gem_handle };
/* Get the fake offset back... */
int ret = intel_ioctl(bufmgr->fd, DRM_IOCTL_I915_GEM_MMAP_GTT, &mmap_arg);
if (ret != 0) {
DBG("%s:%d: Error preparing buffer map %d (%s): %s .\n",
__FILE__, __LINE__, bo->gem_handle, bo->name, strerror(errno));
return NULL;
}
/* and mmap it. */
void *map = os_mmap(0, bo->size, PROT_READ | PROT_WRITE,
MAP_SHARED, bufmgr->fd, mmap_arg.offset);
if (map == MAP_FAILED) {
DBG("%s:%d: Error mapping buffer %d (%s): %s .\n",
__FILE__, __LINE__, bo->gem_handle, bo->name, strerror(errno));
return NULL;
}
/* We don't need to use VALGRIND_MALLOCLIKE_BLOCK because Valgrind will
* already intercept this mmap call. However, for consistency between
* all the mmap paths, we mark the pointer as defined now and mark it
* as inaccessible afterwards.
*/
VG_DEFINED(map, bo->size);
if (p_atomic_cmpxchg(&bo->map_gtt, NULL, map)) {
VG_NOACCESS(map, bo->size);
os_munmap(map, bo->size);
}
}
assert(bo->map_gtt);
DBG("bo_map_gtt: %d (%s) -> %p, ", bo->gem_handle, bo->name, bo->map_gtt);
print_flags(flags);
if (!(flags & MAP_ASYNC)) {
bo_wait_with_stall_warning(dbg, bo, "GTT mapping");
}
return bo->map_gtt;
}
static bool
can_map_cpu(struct iris_bo *bo, unsigned flags)
{

2
src/gallium/drivers/iris/iris_bufmgr.h
View file

@ -186,8 +186,6 @@ struct iris_bo {
/** Mapped address for the buffer, saved across map/unmap cycles */
void *map_cpu;
/** GTT virtual address for the buffer, saved across map/unmap cycles */
void *map_gtt;
/** WC CPU address for the buffer, saved across map/unmap cycles */
void *map_wc;