From 5e9b0b56ad8c2a4289b2b506ad3d0f3acd0d20ba Mon Sep 17 00:00:00 2001
From: Julien Stephan <jstephan@baylibre.com>
Date: Mon, 30 Jun 2025 12:08:16 +0200
Subject: 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 <jstephan@baylibre.com>
---
 cmd/Kconfig     |  6 ++++++
 cmd/Makefile    |  1 +
 cmd/read_edid.c | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 45 insertions(+)
 create mode 100644 cmd/read_edid.c

(limited to 'cmd')

diff --git a/cmd/Kconfig b/cmd/Kconfig
index f21d27cb27f..3018e33ca7d 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1608,6 +1608,12 @@ config CMD_READ
 	help
 	  Provides low-level access to the data in a partition.
 
+config CMD_READ_EDID
+	bool "read_edid - Read display EDID"
+	depends on DISPLAY
+	help
+	  Read and parse edid from connected display device.
+
 config CMD_REMOTEPROC
 	bool "remoteproc"
 	depends on REMOTEPROC
diff --git a/cmd/Makefile b/cmd/Makefile
index 80cf70b7fe8..7cb379c05a0 100644
--- a/cmd/Makefile
+++ b/cmd/Makefile
@@ -154,6 +154,7 @@ obj-$(CONFIG_CMD_WOL) += wol.o
 obj-$(CONFIG_CMD_QFW) += qfw.o
 obj-$(CONFIG_CMD_READ) += read.o
 obj-$(CONFIG_CMD_WRITE) += read.o
+obj-$(CONFIG_CMD_READ_EDID) += read_edid.o
 obj-$(CONFIG_CMD_REGINFO) += reginfo.o
 obj-$(CONFIG_CMD_REMOTEPROC) += remoteproc.o
 obj-$(CONFIG_CMD_RNG) += rng.o
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",
+	""
+);
-- 
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