backend/drm: use libdisplay-info to parse EDID

.builds/alpine.yml

@@ -3,6 +3,7 @@ packages:
   - eudev-dev
   - ffmpeg-dev
   - glslang
+  - libdisplay-info-dev
   - libinput-dev
   - libliftoff-dev
   - libxkbcommon-dev

.builds/archlinux.yml

@@ -3,6 +3,7 @@ packages:
   - clang
   - ffmpeg
   - libinput
+  - libdisplay-info
   - libliftoff
   - libxkbcommon
   - mesa

.builds/freebsd.yml

@@ -24,6 +24,7 @@ packages:
   - x11/xcb-util-renderutil
   - x11/xcb-util-wm
   - x11-servers/xwayland-devel
+  - sysutils/libdisplay-info
   - sysutils/seatd
   - gmake
   - hwdata

README.md

@@ -52,6 +52,7 @@ Install dependencies:
 * pixman
 * [libseat] (optional, for the session)
 * [hwdata] (optional, for the DRM backend)
+* [libdisplay-info] (optional, for the DRM backend)
 * [libliftoff] (optional, for the DRM backend)
 
 If you choose to enable X11 support:
@@ -81,5 +82,6 @@ See [CONTRIBUTING.md].
 [wrapper libraries]: https://gitlab.freedesktop.org/wlroots/wlroots/-/wikis/Projects-which-use-wlroots#wrapper-libraries
 [libseat]: https://git.sr.ht/~kennylevinsen/seatd
 [hwdata]: https://github.com/vcrhonek/hwdata
+[libdisplay-info]: https://gitlab.freedesktop.org/emersion/libdisplay-info
 [libliftoff]: https://gitlab.freedesktop.org/emersion/libliftoff
 [CONTRIBUTING.md]: https://gitlab.freedesktop.org/wlroots/wlroots/-/blob/master/CONTRIBUTING.md

backend/drm/gen_pnpids.sh

@@ -13,12 +13,11 @@ gen_pnps()
 }
 
 cat << EOF
-#include <stdint.h>
-#include <stddef.h>
 #include "backend/drm/util.h"
+
 #define PNP_ID(a, b, c) ((a & 0x1f) << 10) | ((b & 0x1f) << 5) | (c & 0x1f)
-const char *get_pnp_manufacturer(uint16_t code) {
-	switch (code) {
+const char *get_pnp_manufacturer(const char code[static 3]) {
+	switch (PNP_ID(code[0], code[1], code[2])) {
 $(gen_pnps)
 	}
 	return NULL;

backend/drm/meson.build

@@ -5,6 +5,13 @@ hwdata = dependency(
 	not_found_message: 'Required for the DRM backend.',
 )
 
+libdisplay_info = dependency(
+	'libdisplay-info',
+	required: 'drm' in backends,
+	fallback: 'libdisplay-info',
+	not_found_message: 'Required for the DRM backend.',
+)
+
 libliftoff = dependency(
 	'libliftoff',
 	version: '>=0.4.0',
@@ -12,7 +19,7 @@ libliftoff = dependency(
 	required: false,
 )
 
-if not (hwdata.found() and features['session'])
+if not (hwdata.found() and libdisplay_info.found() and features['session'])
 	subdir_done()
 endif
 
@@ -45,4 +52,5 @@ endif
 
 features += { 'drm-backend': true }
 internal_features += { 'libliftoff': libliftoff.found() }
+wlr_deps += libdisplay_info
 wlr_deps += libliftoff

backend/drm/util.c

@@ -3,6 +3,8 @@
 #include <drm_fourcc.h>
 #include <drm_mode.h>
 #include <drm.h>
+#include <libdisplay-info/edid.h>
+#include <libdisplay-info/info.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -48,9 +50,6 @@ enum wlr_output_mode_aspect_ratio get_picture_aspect_ratio(const drmModeModeInfo
 	}
 }
 
-/* See https://en.wikipedia.org/wiki/Extended_Display_Identification_Data for layout of EDID data.
- * We don't parse the EDID properly. We just expect to receive valid data.
- */
 void parse_edid(struct wlr_drm_connector *conn, size_t len, const uint8_t *data) {
 	struct wlr_output *output = &conn->output;
 
@@ -61,62 +60,28 @@ void parse_edid(struct wlr_drm_connector *conn, size_t len, const uint8_t *data)
 	output->model = NULL;
 	output->serial = NULL;
 
-	if (!data || len < 128) {
+	struct di_info *info = di_info_parse_edid(data, len);
+	if (info == NULL) {
+		wlr_log(WLR_ERROR, "Failed to parse EDID");
 		return;
 	}
 
-	uint16_t id = (data[8] << 8) | data[9];
-	const char *manu = get_pnp_manufacturer(id);
-	char pnp_id[4];
+	const struct di_edid *edid = di_info_get_edid(info);
+	const struct di_edid_vendor_product *vendor_product = di_edid_get_vendor_product(edid);
+	char pnp_id[] = {
+		vendor_product->manufacturer[0],
+		vendor_product->manufacturer[1],
+		vendor_product->manufacturer[2],
+		'\0',
+	};
+	const char *manu = get_pnp_manufacturer(vendor_product->manufacturer);
 	if (!manu) {
-		// The ASCII 3-letter manufacturer PnP ID is encoded in 5-bit codes
-		pnp_id[0] = ((id >> 10) & 0x1F) + '@';
-		pnp_id[1] = ((id >> 5) & 0x1F) + '@';
-		pnp_id[2] = ((id >> 0) & 0x1F) + '@';
-		pnp_id[3] = '\0';
 		manu = pnp_id;
 	}
 	output->make = strdup(manu);
 
-	uint16_t model = data[10] | (data[11] << 8);
-	char model_str[32];
-	snprintf(model_str, sizeof(model_str), "0x%04" PRIX16, model);
-
-	uint32_t serial = data[12] | (data[13] << 8) | (data[14] << 8) | (data[15] << 8);
-	char serial_str[32];
-	if (serial != 0) {
-		snprintf(serial_str, sizeof(serial_str), "0x%08" PRIX32, serial);
-	} else {
-		serial_str[0] = '\0';
-	}
-
-	for (size_t i = 72; i <= 108; i += 18) {
-		uint16_t flag = (data[i] << 8) | data[i + 1];
-		if (flag == 0 && data[i + 3] == 0xFC) {
-			snprintf(model_str, sizeof(model_str), "%.13s", &data[i + 5]);
-
-			// Monitor names are terminated by newline if they're too short
-			char *nl = strchr(model_str, '\n');
-			if (nl) {
-				*nl = '\0';
-			}
-		} else if (flag == 0 && data[i + 3] == 0xFF) {
-			snprintf(serial_str, sizeof(serial_str), "%.13s", &data[i + 5]);
-
-			// Monitor serial numbers are terminated by newline if they're too
-			// short
-			char* nl = strchr(serial_str, '\n');
-
-			if (nl) {
-				*nl = '\0';
-			}
-		}
-	}
-
-	output->model = strdup(model_str);
-	if (serial_str[0] != '\0') {
-		output->serial = strdup(serial_str);
-	}
+	output->model = di_info_get_model(info);
+	output->serial = di_info_get_serial(info);
 }
 
 const char *drm_connector_status_str(drmModeConnection status) {

include/backend/drm/util.h

@@ -11,7 +11,7 @@ struct wlr_drm_connector;
 int32_t calculate_refresh_rate(const drmModeModeInfo *mode);
 enum wlr_output_mode_aspect_ratio get_picture_aspect_ratio(const drmModeModeInfo *mode);
 // Returns manufacturer based on pnp id
-const char *get_pnp_manufacturer(uint16_t code);
+const char *get_pnp_manufacturer(const char code[static 3]);
 // Populates the make/model/phys_{width,height} of output from the edid data
 void parse_edid(struct wlr_drm_connector *conn, size_t len, const uint8_t *data);
 const char *drm_connector_status_str(drmModeConnection status);