sna: Suppress log messages for unchanging EDID

Whenever we reprobe an unchanging output and re-read its EDID, we emit a
useless log message. Previously this was squelched by trying to spot
when an EDID was unchanged through the use of its blob.id, however we
need to do a complete check on the contents in case the kernel returns
us a new EDID with the old id. So make a temporary copy of the current
EDID data and only squelch the log messages if the new EDID is an exact
match.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 21 insertions, 1 deletions

diff --git a/src/sna/sna_display.c b/src/sna/sna_display.c
index 6da56be8..a7957eb9 100644
--- a/src/sna/sna_display.c
+++ b/src/sna/sna_display.c
@@ -1951,7 +1951,7 @@ sna_output_attach_edid(xf86OutputPtr output)
 	struct sna *sna = to_sna(output->scrn);
 	struct sna_output *sna_output = output->driver_private;
 	struct drm_mode_get_blob blob;
-	void *raw = NULL;
+	void *old, *raw = NULL;
 	xf86MonPtr mon = NULL;
 
 	if (sna_output->edid_idx == -1)
@@ -1960,6 +1960,12 @@ sna_output_attach_edid(xf86OutputPtr output)
 	raw = sna_output->edid_raw;
 	blob.length = sna_output->edid_len;
 
+	if (blob.length && output->MonInfo) {
+		old = alloca(blob.length);
+		memcpy(old, raw, blob.length);
+	} else
+		old = NULL;
+
 	blob.blob_id = sna_output->prop_values[sna_output->edid_idx];
 	DBG(("%s: attaching EDID id=%d, current=%d\n",
 	     __FUNCTION__, blob.blob_id, sna_output->edid_blob_id));
@@ -1997,6 +2003,20 @@ sna_output_attach_edid(xf86OutputPtr output)
 			goto done;
 	}
 
+	if (old &&
+	    blob.length == sna_output->edid_len &&
+	    memcmp(old, raw, blob.length) == 0) {
+		assert(sna_output->edid_raw == raw);
+		sna_output->edid_blob_id = blob.blob_id;
+		RRChangeOutputProperty(output->randr_output,
+				       MakeAtom("EDID", strlen("EDID"), TRUE),
+				       XA_INTEGER, 8, PropModeReplace,
+				       sna_output->edid_len,
+				       sna_output->edid_raw,
+				       FALSE, FALSE);
+		return;
+	}
+
 skip_read:
 	if (raw) {
 		mon = xf86InterpretEDID(output->scrn->scrnIndex, raw);