[PATCH 8/8] drm/edid: Dump bogus 18 byte descriptors

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

I'm curious if there are any bogus 18 byte descriptors around.
Let's dump them out if we encounter them.

Not sure we'd actually want this, but at least I get to see
if our CI has anything that hits this :)

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/drm_edid.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 8e76efe1654d..4d8303e56536 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -2202,6 +2202,12 @@ static bool is_display_descriptor(const u8 d[18], u8 tag)
 		d[2] == 0x00 && d[3] == tag;
 }
 
+static bool is_any_display_descriptor(const u8 d[18])
+{
+	return d[0] == 0x00 && d[1] == 0x00 &&
+		d[2] == 0x00;
+}
+
 static bool is_detailed_timing_descriptor(const u8 d[18])
 {
 	return d[0] != 0x00 || d[1] != 0x00;
@@ -2209,6 +2215,15 @@ static bool is_detailed_timing_descriptor(const u8 d[18])
 
 typedef void detailed_cb(const struct detailed_timing *timing, void *closure);
 
+static void do_detailed_block(const u8 d[18], detailed_cb *cb, void *closure)
+{
+	if (!is_detailed_timing_descriptor(d) &&
+	    !is_any_display_descriptor(d))
+		DRM_WARN("Unrecognized 18 byte descriptor: %*ph\n", 18, d);
+
+	cb((const struct detailed_timing *)d, closure);
+}
+
 static void
 cea_for_each_detailed_block(const u8 *ext, detailed_cb *cb, void *closure)
 {
@@ -2221,7 +2236,7 @@ cea_for_each_detailed_block(const u8 *ext, detailed_cb *cb, void *closure)
 
 	n = (127 - d) / 18;
 	for (i = 0; i < n; i++)
-		cb((const struct detailed_timing *)(det_base + 18 * i), closure);
+		do_detailed_block(det_base + 18 * i, cb, closure);
 }
 
 static void
@@ -2234,7 +2249,7 @@ vtb_for_each_detailed_block(const u8 *ext, detailed_cb *cb, void *closure)
 		return; /* unknown version */
 
 	for (i = 0; i < n; i++)
-		cb((const struct detailed_timing *)(det_base + 18 * i), closure);
+		do_detailed_block(det_base + 18 * i, cb, closure);
 }
 
 static void
@@ -2247,7 +2262,8 @@ drm_for_each_detailed_block(const u8 *raw_edid, detailed_cb *cb, void *closure)
 		return;
 
 	for (i = 0; i < EDID_DETAILED_TIMINGS; i++)
-		cb(&(edid->detailed_timings[i]), closure);
+		do_detailed_block((const u8 *)&edid->detailed_timings[i],
+				  cb, closure);
 
 	for (i = 1; i <= raw_edid[0x7e]; i++) {
 		const u8 *ext = raw_edid + (i * EDID_LENGTH);
-- 
2.24.1