[PATCH 2/2] drm/panel: simple: Add timings for Raspberry Pi 7" panel

[Tomi Valkeinen]

Add timings for the panel used in Raspberry Pi 7" DSI Display module:
https://www.raspberrypi.com/products/raspberry-pi-touch-display/

This has been tested with version v1.1 of the display module.

The panel is very strict about the back-porch values, they must be
exactly 46 for hbp and 23 for vbp. Other timings can be defined quite
freely.

The panel is exclusive to Raspberry Pi, and different versions of the
display module can have panels from different vendors which are fully
compatible. Also, as the panel vendors are not public, the compatible
string used is "raspberrypi,7inch-dsi".

Note that while the display module has a DSI connector, and the
compatible has "dsi" in it, we use DRM_MODE_CONNECTOR_DPI as the panel
itself is a parallel video panel. The display module (as of v1.1) uses
TC358762 DSI-to-DPI bridge to do the conversion.

We could use DRM_MODE_CONNECTOR_DSI here, which would have the benefit
of showing a "DSI-1" connector to the userspace. However, the panel IS a
DPI panel, and gets its input from a DSI-to-DPI bridge, and the
panel-simple.c behaves differently depending on the connector type used,
so, DRM_MODE_CONNECTOR_DPI it is.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/panel/panel-simple.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/drivers/gpu/drm/panel/panel-simple.c b/drivers/gpu/drm/panel/panel-simple.c
index 91ab280869ba..e75eb20301f2 100644
--- a/drivers/gpu/drm/panel/panel-simple.c
+++ b/drivers/gpu/drm/panel/panel-simple.c
@@ -4208,6 +4208,35 @@ static const struct panel_desc rocktech_rk043fn48h = {
 	.connector_type = DRM_MODE_CONNECTOR_DPI,
 };
 
+static const struct display_timing raspberrypi_7inch_timing = {
+	.pixelclock = { 10000000, 30000000, 50000000 },
+	.hactive = { 800, 800, 800 },
+	.hfront_porch = { 16, 72, 354 },
+	.hsync_len = { 1, 32, 40 },
+	.hback_porch = { 46, 46, 46 },
+	.vactive = { 480, 480, 480 },
+	.vfront_porch = { 7, 21, 147 },
+	.vsync_len = { 1, 2, 20 },
+	.vback_porch = { 23, 23, 23 },
+	.flags = DISPLAY_FLAGS_VSYNC_HIGH | DISPLAY_FLAGS_HSYNC_HIGH,
+	/* Note: the rest of the flags are defined below in bus_flags */
+};
+
+static const struct panel_desc raspberrypi_7inch = {
+	.timings = &raspberrypi_7inch_timing,
+	.num_timings = 1,
+	.bpc = 8,
+	.size = {
+		.width = 154,
+		.height = 86,
+	},
+	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
+	.connector_type = DRM_MODE_CONNECTOR_DPI,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH |
+		DRM_BUS_FLAG_SYNC_DRIVE_POSEDGE |
+		DRM_BUS_FLAG_PIXDATA_DRIVE_POSEDGE,
+};
+
 static const struct display_timing rocktech_rk070er9427_timing = {
 	.pixelclock = { 26400000, 33300000, 46800000 },
 	.hactive = { 800, 800, 800 },
@@ -5490,6 +5519,9 @@ static const struct of_device_id platform_of_match[] = {
 	}, {
 		.compatible = "qishenglong,gopher2b-lcd",
 		.data = &qishenglong_gopher2b_lcd,
+	}, {
+		.compatible = "raspberrypi,7inch-dsi",
+		.data = &raspberrypi_7inch,
 	}, {
 		.compatible = "raystar,rff500f-awh-dnn",
 		.data = &raystar_rff500f_awh_dnn,

-- 
2.43.0