[PATCH v1 2/2] video: simple_panel: add EDID support

[Svyatoslav Ryhel]

Support timing parsing from EDID if panel device tree node
provides DDC i2c bus instead of timings node.

Tested-by: Robert Eckelmann <longnoserob at gmail.com> # ASUS TF201
Tested-by: Agneli <poczt at protonmail.ch> # Toshiba AC100 T20
Signed-off-by: Svyatoslav Ryhel <clamor95 at gmail.com>
---
 drivers/video/Kconfig        |  2 ++
 drivers/video/simple_panel.c | 51 ++++++++++++++++++++++++++++++++++--
 2 files changed, 51 insertions(+), 2 deletions(-)

diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 6f319ba0d5..e2016d73d1 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -240,6 +240,7 @@ config PANEL
 config SIMPLE_PANEL
 	bool "Enable simple panel support"
 	depends on PANEL && BACKLIGHT && DM_GPIO
+	select I2C_EDID
 	default y
 	help
 	  This turns on a simple panel driver that enables a compatible
@@ -1105,6 +1106,7 @@ config SPL_PANEL
 config SPL_SIMPLE_PANEL
 	bool "Enable simple panel support at SPL"
 	depends on SPL_PANEL && SPL_BACKLIGHT && SPL_DM_GPIO
+	select I2C_EDID
 	default y
 	help
 	  This turns on a simple panel driver that enables a compatible
diff --git a/drivers/video/simple_panel.c b/drivers/video/simple_panel.c
index 064c113d2d..f0234349da 100644
--- a/drivers/video/simple_panel.c
+++ b/drivers/video/simple_panel.c
@@ -7,12 +7,16 @@
 #include <common.h>
 #include <backlight.h>
 #include <dm.h>
+#include <edid.h>
+#include <i2c.h>
 #include <log.h>
 #include <mipi_dsi.h>
 #include <panel.h>
 #include <asm/gpio.h>
 #include <power/regulator.h>
 
+#define EDID_I2C_ADDR	0x50
+
 struct simple_panel_priv {
 	struct udevice *reg;
 	struct udevice *backlight;
@@ -53,9 +57,52 @@ static int simple_panel_get_display_timing(struct udevice *dev,
 					   struct display_timing *timings)
 {
 	const void *blob = gd->fdt_blob;
+	struct display_timing edid_timing;
+	struct udevice *panel_ddc, *panel_edid;
+	u8 edid_buf[EDID_SIZE] = { 0 };
+	int ret, bpc;
+
+	/* Check for timing subnode if panel node first */
+	ret = fdtdec_decode_display_timing(blob, dev_of_offset(dev),
+					   0, timings);
+	if (!ret)
+		return ret;
+
+	/* Check for DDC i2c if no timings are provided */
+	ret = uclass_get_device_by_phandle(UCLASS_I2C, dev,
+					   "ddc-i2c-bus",
+					   &panel_ddc);
+	if (ret) {
+		log_debug("%s: cannot get DDC i2c bus: error %d\n",
+			  __func__, ret);
+		return ret;
+	}
+
+	ret = dm_i2c_probe(panel_ddc, EDID_I2C_ADDR, 0, &panel_edid);
+	if (ret) {
+		log_debug("%s: cannot probe EDID: error %d\n",
+			  __func__, ret);
+		return ret;
+	}
 
-	return fdtdec_decode_display_timing(blob, dev_of_offset(dev),
-					    0, timings);
+	ret = dm_i2c_read(panel_edid, 0, edid_buf, sizeof(edid_buf));
+	if (ret) {
+		log_debug("%s: cannot dump EDID buffer: error %d\n",
+			  __func__, ret);
+		return ret;
+	}
+
+	ret = edid_get_timing(edid_buf, sizeof(edid_buf),
+			      &edid_timing, &bpc);
+	if (ret) {
+		log_debug("%s: cannot decode EDID info: error %d\n",
+			  __func__, ret);
+		return ret;
+	}
+
+	memcpy(timings, &edid_timing, sizeof(*timings));
+
+	return 0;
 }
 
 static int simple_panel_of_to_plat(struct udevice *dev)
-- 
2.40.1