drm/panel: sitronix-st7789v: avoid hardcoding polarity info

Add polarity information via mode and bus flags, so that they are no
longer hardcoded and forward the information to the DRM stack. This is
required for adding panels with different settings.
Reviewed-by: Michael Riesch <michael.riesch@wolfvision.net>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230714013756.1546769-13-sre@kernel.org

drivers/gpu/drm/panel/panel-sitronix-st7789v.c

@@ -28,6 +28,7 @@
 #define ST7789V_RGBCTRL_VSYNC_HIGH		BIT(3)
 #define ST7789V_RGBCTRL_HSYNC_HIGH		BIT(2)
 #define ST7789V_RGBCTRL_PCLK_HIGH		BIT(1)
+#define ST7789V_RGBCTRL_DE_LOW			BIT(0)
 #define ST7789V_RGBCTRL_VBP(n)			((n) & 0x7f)
 #define ST7789V_RGBCTRL_HBP(n)			((n) & 0x1f)
 
@@ -112,6 +113,7 @@
 struct st7789_panel_info {
 	const struct drm_display_mode *mode;
 	u32 bus_format;
+	u32 bus_flags;
 	bool invert_mode;
 };
 
@@ -168,12 +170,15 @@ static const struct drm_display_mode default_mode = {
 	.vtotal = 320 + 8 + 4 + 4,
 	.width_mm = 61,
 	.height_mm = 103,
+	.flags = DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC,
 };
 
 static const struct st7789_panel_info default_panel = {
 	.mode = &default_mode,
 	.invert_mode = true,
 	.bus_format = MEDIA_BUS_FMT_RGB666_1X18,
+	.bus_flags = DRM_BUS_FLAG_DE_HIGH |
+		     DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE,
 };
 
 static int st7789v_get_modes(struct drm_panel *panel,
@@ -198,6 +203,7 @@ static int st7789v_get_modes(struct drm_panel *panel,
 	connector->display_info.bpc = 6;
 	connector->display_info.width_mm = ctx->info->mode->width_mm;
 	connector->display_info.height_mm = ctx->info->mode->height_mm;
+	connector->display_info.bus_flags = ctx->info->bus_flags;
 	drm_display_info_set_bus_formats(&connector->display_info,
 					 &ctx->info->bus_format, 1);
 
@@ -207,7 +213,7 @@ static int st7789v_get_modes(struct drm_panel *panel,
 static int st7789v_prepare(struct drm_panel *panel)
 {
 	struct st7789v *ctx = panel_to_st7789v(panel);
-	u8 pixel_fmt;
+	u8 pixel_fmt, polarity;
 	int ret;
 
 	switch (ctx->info->bus_format) {
@@ -225,6 +231,16 @@ static int st7789v_prepare(struct drm_panel *panel)
 
 	pixel_fmt = (pixel_fmt << 4) | pixel_fmt;
 
+	polarity = 0;
+	if (ctx->info->mode->flags & DRM_MODE_FLAG_PVSYNC)
+		polarity |= ST7789V_RGBCTRL_VSYNC_HIGH;
+	if (ctx->info->mode->flags & DRM_MODE_FLAG_PHSYNC)
+		polarity |= ST7789V_RGBCTRL_HSYNC_HIGH;
+	if (ctx->info->bus_flags & DRM_BUS_FLAG_PIXDATA_SAMPLE_NEGEDGE)
+		polarity |= ST7789V_RGBCTRL_PCLK_HIGH;
+	if (ctx->info->bus_flags & DRM_BUS_FLAG_DE_LOW)
+		polarity |= ST7789V_RGBCTRL_DE_LOW;
+
 	ret = regulator_enable(ctx->power);
 	if (ret)
 		return ret;
@@ -340,9 +356,7 @@ static int st7789v_prepare(struct drm_panel *panel)
 	ST7789V_TEST(ret, st7789v_write_command(ctx, ST7789V_RGBCTRL_CMD));
 	ST7789V_TEST(ret, st7789v_write_data(ctx, ST7789V_RGBCTRL_WO |
 					     ST7789V_RGBCTRL_RCM(2) |
-					     ST7789V_RGBCTRL_VSYNC_HIGH |
-					     ST7789V_RGBCTRL_HSYNC_HIGH |
-					     ST7789V_RGBCTRL_PCLK_HIGH));
+					     polarity));
 	ST7789V_TEST(ret, st7789v_write_data(ctx, ST7789V_RGBCTRL_VBP(8)));
 	ST7789V_TEST(ret, st7789v_write_data(ctx, ST7789V_RGBCTRL_HBP(20)));