Merge patch series "video: display: refactor display_read_timing to avoid code duplication"

Julien Stephan <jstephan@baylibre.com> says:

Commit 2dcf143398 ("dm: video: Repurpose the 'displayport' uclass to 'display'")
left the display_read_edid() function unused by mistake.

This series addresses that oversight and introduces a new useful cmd.

Patch 1:
 - Refactors display_read_timing() to use the existing
   display_read_edid() function, eliminating redundant code.
 - Marks display_read_edid() as static since it is not used outside of
   the file.

Patch 2:
 - Adds a new read_edid command, which can be very useful for debugging
   or developing new display drivers.
 - As this command uses display_read_edid(), the function is made
   non-static again.

Link: https://lore.kernel.org/r/20250630-read_edid_cleanup-v1-0-ec7d425472c7@baylibre.com

cmd/Kconfig

@@ -1692,6 +1692,12 @@ 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

cmd/Makefile

@@ -157,6 +157,7 @@ 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

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",
+	""
+);