drm/xe/oa: Allow reading after disabling OA stream

Some OA data might be present in the OA buffer when OA stream is
disabled. Allow UMD's to retrieve this data, so that all data till the
point when OA stream is disabled can be retrieved.

v2: Update tail pointer after disable (Umesh)

Fixes: efb315d ("drm/xe/oa/uapi: Read file_operation")
Cc: stable@vger.kernel.org
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Umesh Nerlige Ramappa<umesh.nerlige.ramappa@intel.com>
Link: https://patch.msgid.link/20260313053630.3176100-1-ashutosh.dixit@intel.com
(cherry picked from commit 4ff57c5)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

Author: ashutoshx

drivers/gpu/drm/xe/xe_oa.c

@@ -543,8 +543,7 @@ static ssize_t xe_oa_read(struct file *file, char __user *buf,
 	size_t offset = 0;
 	int ret;
 
-	/* Can't read from disabled streams */
-	if (!stream->enabled || !stream->sample)
+	if (!stream->sample)
 		return -EINVAL;
 
 	if (!(file->f_flags & O_NONBLOCK)) {
@@ -1460,6 +1459,10 @@ static void xe_oa_stream_disable(struct xe_oa_stream *stream)
 
 	if (stream->sample)
 		hrtimer_cancel(&stream->poll_check_timer);
+
+	/* Update stream->oa_buffer.tail to allow any final reports to be read */
+	if (xe_oa_buffer_check_unlocked(stream))
+		wake_up(&stream->poll_wq);
 }
 
 static int xe_oa_enable_preempt_timeslice(struct xe_oa_stream *stream)