uapi/drm/i915: document field usage of drm_i915_perf_oa_config

Document the expected length of buffers config pointers (tuple of u32
values).

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20170918114241.30105-1-lionel.g.landwerlin@intel.com

diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
index b4505d55990d6ba4dcf9e479dd45b0810fe06191..fe25a01c81f22661cb5c8a7d3db34a7851e579b3 100644 (file)
--- a/include/uapi/drm/i915_drm.h
+++ b/include/uapi/drm/i915_drm.h
@@ -1511,6 +1511,11 @@ struct drm_i915_perf_oa_config {
        __u32 n_boolean_regs;
        __u32 n_flex_regs;
 
+       /*
+        * These fields are pointers to tuples of u32 values (register
+        * address, value). For example the expected length of the buffer
+        * pointed by mux_regs_ptr is (2 * sizeof(u32) * n_mux_regs).
+        */
        __u64 mux_regs_ptr;
        __u64 boolean_regs_ptr;
        __u64 flex_regs_ptr;