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authorGravatar Mauro Carvalho Chehab <mchehab+samsung@kernel.org> 2018-12-05 13:16:24 -0500
committerGravatar Mauro Carvalho Chehab <mchehab+samsung@kernel.org> 2018-12-05 13:23:38 -0500
commit14a4467a0a5eacb2ebbe3aab1b4e25af3519c76a (patch)
tree541647056606d3e0aa1e06e62d2b40417623f8cb /tools/include/uapi/drm/i915_drm.h
parentmedia: pixfmt-meta-d4xx.rst: Add a license to it (diff)
parentMerge tag 'media/v4.20-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mc... (diff)
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Merge commit '0072a0c14d5b7cb72c611d396f143f5dcd73ebe2' into patchwork
Merge from Upstream after the latest media fixes branch, because we need one patch that it is there. * commit '0072a0c14d5b7cb72c611d396f143f5dcd73ebe2': (1108 commits) ide: Change to use DEFINE_SHOW_ATTRIBUTE macro ide: pmac: add of_node_put() drivers/tty: add missing of_node_put() drivers/sbus/char: add of_node_put() sbus: char: add of_node_put() Linux 4.20-rc5 PCI: Fix incorrect value returned from pcie_get_speed_cap() MAINTAINERS: Update linux-mips mailing list address ocfs2: fix potential use after free mm/khugepaged: fix the xas_create_range() error path mm/khugepaged: collapse_shmem() do not crash on Compound mm/khugepaged: collapse_shmem() without freezing new_page mm/khugepaged: minor reorderings in collapse_shmem() mm/khugepaged: collapse_shmem() remember to clear holes mm/khugepaged: fix crashes due to misaccounted holes mm/khugepaged: collapse_shmem() stop if punched or truncated mm/huge_memory: fix lockdep complaint on 32-bit i_size_read() mm/huge_memory: splitting set mapping+index before unfreeze mm/huge_memory: rename freeze_page() to unmap_page() initramfs: clean old path before creating a hardlink ...
Diffstat (limited to 'tools/include/uapi/drm/i915_drm.h')
-rw-r--r--tools/include/uapi/drm/i915_drm.h22
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 {
*/
#define I915_PARAM_CS_TIMESTAMP_FREQUENCY 51
+/*
+ * 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.
+ */
+#define I915_PARAM_MMAP_GTT_COHERENT 52
+
typedef struct drm_i915_getparam {
__s32 param;
/*