drm/bridge: Add timing support to dumb VGA DAC

This extends the dumb VGA DAC bridge to handle the THS8134A
and THS8134B VGA DACs in addition to those already handled.

We assign the proper timing data to the pointer inside the
bridge struct so display controllers that need to align their
timings to the bridge can pick it up and work from there.

Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NArchit Taneja <architt@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180112074854.9560-3-linus.walleij@linaro.org

drivers/gpu/drm/bridge/dumb-vga-dac.c

@@ -11,6 +11,7 @@
  */
 
 #include <linux/module.h>
+#include <linux/of_device.h>
 #include <linux/of_graph.h>
 #include <linux/regulator/consumer.h>
 
@@ -204,6 +205,7 @@ static int dumb_vga_probe(struct platform_device *pdev)
 
 	vga->bridge.funcs = &dumb_vga_bridge_funcs;
 	vga->bridge.of_node = pdev->dev.of_node;
+	vga->bridge.timings = of_device_get_match_data(&pdev->dev);
 
 	drm_bridge_add(&vga->bridge);
 
@@ -222,10 +224,61 @@ static int dumb_vga_remove(struct platform_device *pdev)
 	return 0;
 }
 
+/*
+ * We assume the ADV7123 DAC is the "default" for historical reasons
+ * Information taken from the ADV7123 datasheet, revision D.
+ * NOTE: the ADV7123EP seems to have other timings and need a new timings
+ * set if used.
+ */
+static const struct drm_bridge_timings default_dac_timings = {
+	/* Timing specifications, datasheet page 7 */
+	.sampling_edge = DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	.setup_time_ps = 500,
+	.hold_time_ps = 1500,
+};
+
+/*
+ * Information taken from the THS8134, THS8134A, THS8134B datasheet named
+ * "SLVS205D", dated May 1990, revised March 2000.
+ */
+static const struct drm_bridge_timings ti_ths8134_dac_timings = {
+	/* From timing diagram, datasheet page 9 */
+	.sampling_edge = DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	/* From datasheet, page 12 */
+	.setup_time_ps = 3000,
+	/* I guess this means latched input */
+	.hold_time_ps = 0,
+};
+
+/*
+ * Information taken from the THS8135 datasheet named "SLAS343B", dated
+ * May 2001, revised April 2013.
+ */
+static const struct drm_bridge_timings ti_ths8135_dac_timings = {
+	/* From timing diagram, datasheet page 14 */
+	.sampling_edge = DRM_BUS_FLAG_PIXDATA_POSEDGE,
+	/* From datasheet, page 16 */
+	.setup_time_ps = 2000,
+	.hold_time_ps = 500,
+};
+
 static const struct of_device_id dumb_vga_match[] = {
-	{ .compatible = "dumb-vga-dac" },
-	{ .compatible = "adi,adv7123" },
-	{ .compatible = "ti,ths8135" },
+	{
+		.compatible = "dumb-vga-dac",
+		.data = NULL,
+	},
+	{
+		.compatible = "adi,adv7123",
+		.data = &default_dac_timings,
+	},
+	{
+		.compatible = "ti,ths8135",
+		.data = &ti_ths8135_dac_timings,
+	},
+	{
+		.compatible = "ti,ths8134",
+		.data = &ti_ths8134_dac_timings,
+	},
 	{},
 };
 MODULE_DEVICE_TABLE(of, dumb_vga_match);