[PATCH 1/3] drm/xe/xe_oa: Clear status only if relevant bits are set

[Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>]

OA monitors only a few bits in the status field. The current
read-modify-write will write to the MMIO even if none of the relevant
bits are set. Clear the status only if relevant bits are set.

Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
---
v2: Move comment (Ashutosh)
---
 drivers/gpu/drm/xe/xe_oa.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_oa.c b/drivers/gpu/drm/xe/xe_oa.c
index b460fcdfca15..024940478c06 100644
--- a/drivers/gpu/drm/xe/xe_oa.c
+++ b/drivers/gpu/drm/xe/xe_oa.c
@@ -542,15 +542,17 @@ static int xe_oa_wait_unlocked(struct xe_oa_stream *stream)
 static int __xe_oa_read(struct xe_oa_stream *stream, char __user *buf,
 			size_t count, size_t *offset)
 {
-	/* Only clear our bits to avoid side-effects */
-	stream->oa_status = xe_mmio_rmw32(&stream->gt->mmio, __oa_regs(stream)->oa_status,
-					  OASTATUS_RELEVANT_BITS, 0);
+	stream->oa_status = xe_mmio_read32(&stream->gt->mmio, __oa_regs(stream)->oa_status);
 	/*
 	 * Signal to userspace that there is non-zero OA status to read via
 	 * @DRM_XE_OBSERVATION_IOCTL_STATUS observation stream fd ioctl
 	 */
-	if (stream->oa_status & OASTATUS_RELEVANT_BITS)
+	if (stream->oa_status & OASTATUS_RELEVANT_BITS) {
+		/* Only clear our bits to avoid side-effects */
+		xe_mmio_write32(&stream->gt->mmio, __oa_regs(stream)->oa_status,
+				stream->oa_status & ~OASTATUS_RELEVANT_BITS);
 		return -EIO;
+	}
 
 	return xe_oa_append_reports(stream, buf, count, offset);
 }
-- 
2.51.0