[PATCH 3/6] drm: bridge: dw-hdmi: Introduce previous_pixelclock/previous_tmdsclock

[Algea Cao]

Introduce previous_pixelclock/previous_tmdsclock to
determine whether PHY needs initialization. If phy is power off,
or mpixelclock/mtmdsclock is different to previous value, phy is
neet to be reinitialized.

Signed-off-by: Algea Cao <algea.cao@xxxxxxxxxxxxxx>
---

 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 50 +++++++++++++++++++----
 1 file changed, 43 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index a1a81fc768c2..1eb4736b9b59 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -101,6 +101,8 @@ static const u16 csc_coeff_rgb_full_to_rgb_limited[3][4] = {
 struct hdmi_vmode {
 	bool mdataenablepolarity;
 
+	unsigned int previous_pixelclock;
+	unsigned int previous_tmdsclock;
 	unsigned int mpixelclock;
 	unsigned int mpixelrepetitioninput;
 	unsigned int mpixelrepetitionoutput;
@@ -890,6 +892,32 @@ static int hdmi_bus_fmt_color_depth(unsigned int bus_format)
 	}
 }
 
+static unsigned int
+hdmi_get_tmdsclock(struct dw_hdmi *hdmi, unsigned long mpixelclock)
+{
+	unsigned int tmdsclock = mpixelclock;
+	unsigned int depth =
+		hdmi_bus_fmt_color_depth(hdmi->hdmi_data.enc_out_bus_format);
+
+	if (!hdmi_bus_fmt_is_yuv422(hdmi->hdmi_data.enc_out_bus_format)) {
+		switch (depth) {
+		case 16:
+			tmdsclock = mpixelclock * 2;
+			break;
+		case 12:
+			tmdsclock = mpixelclock * 3 / 2;
+			break;
+		case 10:
+			tmdsclock = mpixelclock * 5 / 4;
+			break;
+		default:
+			break;
+		}
+	}
+
+	return tmdsclock;
+}
+
 /*
  * this submodule is responsible for the video data synchronization.
  * for example, for RGB 4:4:4 input, the data map is defined as
@@ -1861,11 +1889,13 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
 	int hblank, vblank, h_de_hs, v_de_vs, hsync_len, vsync_len;
 	unsigned int vdisplay, hdisplay;
 
+	vmode->previous_pixelclock = vmode->mpixelclock;
 	vmode->mpixelclock = mode->clock * 1000;
 
 	dev_dbg(hdmi->dev, "final pixclk = %d\n", vmode->mpixelclock);
 
-	vmode->mtmdsclock = vmode->mpixelclock;
+	vmode->previous_tmdsclock = vmode->mtmdsclock;
+	vmode->mtmdsclock = hdmi_get_tmdsclock(hdmi, vmode->mpixelclock);
 
 	if (!hdmi_bus_fmt_is_yuv422(hdmi->hdmi_data.enc_out_bus_format)) {
 		switch (hdmi_bus_fmt_color_depth(
@@ -2172,12 +2202,18 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi,
 	hdmi_av_composer(hdmi, &connector->display_info, mode);
 
 	/* HDMI Initializateion Step B.2 */
-	ret = hdmi->phy.ops->init(hdmi, hdmi->phy.data,
-				  &connector->display_info,
-				  &hdmi->previous_mode);
-	if (ret)
-		return ret;
-	hdmi->phy.enabled = true;
+	if (!hdmi->phy.enabled ||
+	    hdmi->hdmi_data.video_mode.previous_pixelclock !=
+	    hdmi->hdmi_data.video_mode.mpixelclock ||
+	    hdmi->hdmi_data.video_mode.previous_tmdsclock !=
+	    hdmi->hdmi_data.video_mode.mtmdsclock) {
+		ret = hdmi->phy.ops->init(hdmi, hdmi->phy.data,
+					  &connector->display_info,
+					  &hdmi->previous_mode);
+		if (ret)
+			return ret;
+		hdmi->phy.enabled = true;
+	}
 
 	/* HDMI Initialization Step B.3 */
 	dw_hdmi_enable_video_path(hdmi);
-- 
2.25.1