[Intel-gfx] [PATCH 4/5] drm/i915/perf: no head/tail ref in gen7_oa_read

Matthew Auld matthew.william.auld at gmail.com
Wed Jan 25 15:56:47 UTC 2017

On 24 January 2017 at 01:25, Robert Bragg <robert at sixbynine.org> wrote:
> This avoids redundantly passing an (inout) head and tail pointer to
> gen7_append_oa_reports() from gen7_oa_read which doesn't need to
> reference either itself.
> Moving the head/tail reads and writes into gen7_append_oa_reports should
> have no functional effect except to avoid some redundant head pointer
> writes in cases where nothing was copied to userspace.
> This is a stepping stone towards updating how the head and tail pointer
> state is managed to improve the workaround for the OA unit's tail
> pointer race. It reduces the number of places we need to read/write the
> head and tail pointers.
> Signed-off-by: Robert Bragg <robert at sixbynine.org>
Reviewed-by: Matthew Auld <matthew.auld at intel.com>

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