edid: document that DTD size in mm can be unset
According to table 3.21 note 17, these fields should be set to zero
for some sinks, e.g. front projectors.
edid-decode hides the size from its output if both fields are zero.
Signed-off-by: Simon Ser <contact@emersion.fr>
diff --git a/di-edid-decode.c b/di-edid-decode.c
index 27db286..e02cf5f 100644
--- a/di-edid-decode.c
+++ b/di-edid-decode.c
@@ -58,7 +58,9 @@
printf(" %3u:%-3u", horiz_ratio, vert_ratio);
printf(" %8.3f kHz %13.6f MHz", horiz_freq_hz / 1000,
(double) def->pixel_clock_hz / (1000 * 1000));
- printf(" (%d mm x %d mm)", def->horiz_image_mm, def->vert_image_mm);
+ if (def->horiz_image_mm != 0 || def->vert_image_mm != 0) {
+ printf(" (%d mm x %d mm)", def->horiz_image_mm, def->vert_image_mm);
+ }
printf("\n");
horiz_back_porch = hbl - def->horiz_sync_pulse - def->horiz_front_porch;
diff --git a/include/libdisplay-info/edid.h b/include/libdisplay-info/edid.h
index b16c1b9..fe58803 100644
--- a/include/libdisplay-info/edid.h
+++ b/include/libdisplay-info/edid.h
@@ -190,7 +190,7 @@
int horiz_front_porch, vert_front_porch;
/* Horizontal/Vertical Sync Pulse Width in pixels/lines */
int horiz_sync_pulse, vert_sync_pulse;
- /* Horizontal/Vertical Addressable Video Image Size in mm */
+ /* Horizontal/Vertical Addressable Video Image Size in mm, zero if unset */
int horiz_image_mm, vert_image_mm;
/* Horizontal/Vertical Border in pixels/lines */
int horiz_border, vert_border;
