drm/panel: simple: Add support for Giantplus GPG482739QS5

This patch adds support for the GiantPlus GPG48273QS5 4.3" WQVGA TFT LCD
panel to the simple-panel driver.

This panel is connected via a parallel bus and uses both HSYNC and
VSYNC, whose lengths are unfortunately not clearly defined. The
datasheet only specifies the front- and backporch length, but the timing
diagram suggests that both sync signals should be asserted for exactly
one clock cycle.
Signed-off-by: Philipp Zabel <philipp.zabel@gmail.com>
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>

Documentation/devicetree/bindings/panel/giantplus,gpg482739qs5.txt

+GiantPlus GPG48273QS5 4.3" (480x272) WQVGA TFT LCD panel
+
+Required properties:
+- compatible: should be "giantplus,gpg48273qs5"
+
+This binding is compatible with the simple-panel binding, which is specified
+in simple-panel.txt in this directory.

drivers/gpu/drm/panel/panel-simple.c

@@ -566,6 +566,29 @@ static const struct panel_desc foxlink_fl500wvr00_a0t = {
 	.bus_format = MEDIA_BUS_FMT_RGB888_1X24,
 };
 
+static const struct drm_display_mode giantplus_gpg482739qs5_mode = {
+	.clock = 9000,
+	.hdisplay = 480,
+	.hsync_start = 480 + 5,
+	.hsync_end = 480 + 5 + 1,
+	.htotal = 480 + 5 + 1 + 40,
+	.vdisplay = 272,
+	.vsync_start = 272 + 8,
+	.vsync_end = 272 + 8 + 1,
+	.vtotal = 272 + 8 + 1 + 8,
+	.vrefresh = 60,
+};
+
+static const struct panel_desc giantplus_gpg482739qs5 = {
+	.modes = &giantplus_gpg482739qs5_mode,
+	.num_modes = 1,
+	.bpc = 8,
+	.size = {
+		.width = 95,
+		.height = 54,
+	},
+};
+
 static const struct drm_display_mode hannstar_hsd070pww1_mode = {
 	.clock = 71100,
 	.hdisplay = 1280,
@@ -762,6 +785,9 @@ static const struct of_device_id platform_of_match[] = {
 	}, {
 		.compatible = "foxlink,fl500wvr00-a0t",
 		.data = &foxlink_fl500wvr00_a0t,
+	}, {
+		.compatible = "giantplus,gpg482739qs5",
+		.data = &giantplus_gpg482739qs5
 	}, {
 		.compatible = "hannstar,hsd070pww1",
 		.data = &hannstar_hsd070pww1,