edid-decode: improve DisplayID native format handling

The DisplayID 1.3 reporting of the native format was off by 1.

Also check if the resolution is either all 0 (no native format
specified) or all non-0.

Finally check for consistency with the reported native resolution
by the CTA block.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

3 files changed, 27 insertions, 4 deletions

diff --git a/edid-decode.h b/edid-decode.h
index e24c300..51c6173 100644
--- a/edid-decode.h
+++ b/edid-decode.h
@@ -138,6 +138,7 @@ struct edid_state {
 
 		// DisplayID block state
 		dispid.version = 0;
+		dispid.native_width = dispid.native_height = 0;
 		dispid.preparsed_color_ids = dispid.preparsed_xfer_ids = 0;
 		dispid.preparsed_displayid_blocks = 0;
 		dispid.is_base_block = true;
@@ -246,6 +247,7 @@ struct edid_state {
 		bool has_type_1_7;
 		bool has_display_interface_features;
 		vec_timings_ext preferred_timings;
+		unsigned native_width, native_height;
 		// Keep track of the found CTA-861 Tag/Extended Tag pairs.
 		// The unsigned value is equal to: (tag << 8) | ext_tag
 		std::set<unsigned> found_tags;
diff --git a/parse-cta-block.cpp b/parse-cta-block.cpp
index 8f759eb..aa19553 100644
--- a/parse-cta-block.cpp
+++ b/parse-cta-block.cpp
@@ -2438,4 +2438,11 @@ void edid_state::check_cta_blocks()
 		warn("Native interlaced resolution of %ux%u is smaller than the max preferred interlaced resolution %ux%u.\n",
 		     native_ilace_hact, native_ilace_vact,
 		     max_pref_ilace_hact, max_pref_ilace_vact);
+
+	if (dispid.native_width && native_prog_hact &&
+	    !native_prog_mixed_resolutions) {
+		if (dispid.native_width != native_prog_hact ||
+		    dispid.native_height != native_prog_vact)
+			fail("Mismatch between CTA-861 and DisplayID native progressive resolution.\n");
+	}
 }
diff --git a/parse-displayid-block.cpp b/parse-displayid-block.cpp
index 36985e2..ca3e73d 100644
--- a/parse-displayid-block.cpp
+++ b/parse-displayid-block.cpp
@@ -590,8 +590,15 @@ void edid_state::parse_displayid_display_device(const unsigned char *x)
 		printf("    The backlight may be switched on and off\n");
 	if (x[4] & 0x04)
 		printf("    The backlight's intensity can be controlled\n");
-	printf("    Display native pixel format: %ux%u\n",
-	       x[5] | (x[6] << 8), x[7] | (x[8] << 8));
+	unsigned w = x[5] | (x[6] << 8);
+	unsigned h = x[7] | (x[8] << 8);
+	if (w && h) {
+		printf("    Display native pixel format: %ux%u\n", w + 1, h + 1);
+		dispid.native_width = w + 1;
+		dispid.native_height = h + 1;
+	} else if (w || h) {
+		fail("Invalid Native Pixel Format %ux%u.\n", w, h);
+	}
 	printf("    Aspect ratio and orientation:\n");
 	printf("      Aspect Ratio: %.2f\n", (100 + x[9]) / 100.0);
 	unsigned char v = x[0x0a];
@@ -1114,8 +1121,15 @@ void edid_state::parse_displayid_parameters_v2(const unsigned char *x,
 	else
 		printf("    Image size: %.1f mm x %.1f mm\n",
 		       hor_size / 10.0, vert_size / 10.0);
-	printf("    Pixels: %d x %d\n",
-	       (x[8] << 8) + x[7], (x[10] << 8) + x[9]);
+	unsigned w = (x[8] << 8) + x[7];
+	unsigned h = (x[10] << 8) + x[9];
+	if (w && h) {
+		printf("    Native Format: %ux%u\n", w, h);
+		dispid.native_width = w;
+		dispid.native_height = h;
+	} else if (w || h) {
+		fail("Invalid Native Format %ux%u.\n", w, h);
+	}
 	unsigned char v = x[11];
 	printf("    Scan Orientation: ");
 	switch (v & 0x07) {