cmd: add new command to read edid

Add a new command to read EDID info from connected display.

When applicable EDID can also be retrieved by commands such as:

  i2c dev x
  i2c edid 0x50

but the new read_edid function relies on the implementation of the
read_edid callback from DISPLAY driver.

Signed-off-by: Julien Stephan <[email protected]>

1 files changed, 38 insertions, 0 deletions

diff --git a/cmd/read_edid.c b/cmd/read_edid.c
new file mode 100644
index 00000000000..428dddca8bb
--- /dev/null
+++ b/cmd/read_edid.c
@@ -0,0 +1,38 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2025 BayLibre, SAS
+ */
+
+#include <command.h>
+#include <dm.h>
+#include <display.h>
+#include <edid.h>
+
+static int do_read_edid(struct cmd_tbl *cmdtp, int flag, int argc, char * const argv[])
+{
+	struct udevice *dev;
+	int ret;
+	u8 edid[EDID_EXT_SIZE];
+
+	/* Get the first display device (UCLASS_DISPLAY) */
+	ret = uclass_first_device_err(UCLASS_DISPLAY, &dev);
+	if (ret) {
+		printf("Cannot get display device: %d\n", ret);
+		return CMD_RET_FAILURE;
+	}
+
+	ret = display_read_edid(dev, edid, EDID_EXT_SIZE);
+	if (ret) {
+		printf("Cannot read edid: %d\n", ret);
+		return CMD_RET_FAILURE;
+	}
+
+	edid_print_info((struct edid1_info *)edid);
+
+	return CMD_RET_SUCCESS;
+}
+
+U_BOOT_CMD(read_edid, 1, 0, do_read_edid,
+	"Read and print EDID from display",
+	""
+);