path: root/tools
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authorArnaldo Carvalho de Melo <acme@redhat.com>2018-11-19 12:17:42 -0800
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-11-19 12:17:42 -0800
commit53f00f4548ef700e3c6867a35fd7d4f824cd165a (patch)
tree0515d4e691b1dcd1d035820215ad74df007458b3 /tools
parentperf tools: Restore proper cwd on return from mnt namespace (diff)
tools headers uapi: Synchronize i915_drm.h
To pick up the changes in: 900ccf30f9e1 ("drm/i915: Only force GGTT coherency w/a on required chipsets") No changes are required in tools/ nor does anything gets automatically generated to be used in the 'perf trace' syscall arg beautifiers. This silences this perf build warning: Warning: Kernel ABI header at 'tools/include/uapi/drm/i915_drm.h' differs from latest version at 'include/uapi/drm/i915_drm.h' diff -u tools/include/uapi/drm/i915_drm.h include/uapi/drm/i915_drm.h Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Link: https://lkml.kernel.org/n/tip-t2vor2wegv41gt5n49095kly@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
1 files changed, 22 insertions, 0 deletions
diff --git a/tools/include/uapi/drm/i915_drm.h b/tools/include/uapi/drm/i915_drm.h
index 7f5634ce8e88..a4446f452040 100644
--- a/tools/include/uapi/drm/i915_drm.h
+++ b/tools/include/uapi/drm/i915_drm.h
@@ -529,6 +529,28 @@ typedef struct drm_i915_irq_wait {
+ * Once upon a time we supposed that writes through the GGTT would be
+ * immediately in physical memory (once flushed out of the CPU path). However,
+ * on a few different processors and chipsets, this is not necessarily the case
+ * as the writes appear to be buffered internally. Thus a read of the backing
+ * storage (physical memory) via a different path (with different physical tags
+ * to the indirect write via the GGTT) will see stale values from before
+ * the GGTT write. Inside the kernel, we can for the most part keep track of
+ * the different read/write domains in use (e.g. set-domain), but the assumption
+ * of coherency is baked into the ABI, hence reporting its true state in this
+ * parameter.
+ *
+ * Reports true when writes via mmap_gtt are immediately visible following an
+ * lfence to flush the WCB.
+ *
+ * Reports false when writes via mmap_gtt are indeterminately delayed in an in
+ * internal buffer and are _not_ immediately visible to third parties accessing
+ * directly via mmap_cpu/mmap_wc. Use of mmap_gtt as part of an IPC
+ * communications channel when reporting false is strongly disadvised.
+ */
typedef struct drm_i915_getparam {
__s32 param;