[PATCH RFC 4/8] drm/bridge: dw-hdmi: add support for YUV420 output

[Neil Armstrong <narmstrong@baylibre.com>]

In order to support the HDMI2.0 YUV420 display modes, this patch
adds support for the YUV420 TMDS Clock divided by 2 and the controller
passthrough mode.

This patch is based on work from Zheng Yang <zhengyang@rock-chips.com> in
the Rockchip Linux 4.4 BSP at [1]

[1] https://github.com/rockchip-linux/kernel/tree/release-4.4

Cc: Zheng Yang <zhengyang@rock-chips.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 63 ++++++++++++++++++-----
 1 file changed, 50 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index 523508af70b0..0b07bda73ffd 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -94,6 +94,7 @@ struct hdmi_vmode {
 	unsigned int mpixelclock;
 	unsigned int mpixelrepetitioninput;
 	unsigned int mpixelrepetitionoutput;
+	unsigned int mtmdsclock;
 };
 
 struct hdmi_data_info {
@@ -538,7 +539,7 @@ static void hdmi_init_clk_regenerator(struct dw_hdmi *hdmi)
 static void hdmi_clk_regenerator_update_pixel_clock(struct dw_hdmi *hdmi)
 {
 	mutex_lock(&hdmi->audio_mutex);
-	hdmi_set_clk_regenerator(hdmi, hdmi->hdmi_data.video_mode.mpixelclock,
+	hdmi_set_clk_regenerator(hdmi, hdmi->hdmi_data.video_mode.mtmdsclock,
 				 hdmi->sample_rate);
 	mutex_unlock(&hdmi->audio_mutex);
 }
@@ -547,7 +548,7 @@ void dw_hdmi_set_sample_rate(struct dw_hdmi *hdmi, unsigned int rate)
 {
 	mutex_lock(&hdmi->audio_mutex);
 	hdmi->sample_rate = rate;
-	hdmi_set_clk_regenerator(hdmi, hdmi->hdmi_data.video_mode.mpixelclock,
+	hdmi_set_clk_regenerator(hdmi, hdmi->hdmi_data.video_mode.mtmdsclock,
 				 hdmi->sample_rate);
 	mutex_unlock(&hdmi->audio_mutex);
 }
@@ -648,6 +649,20 @@ static bool hdmi_bus_fmt_is_yuv422(unsigned int bus_format)
 	}
 }
 
+static bool hdmi_bus_fmt_is_yuv420(unsigned int bus_format)
+{
+	switch (bus_format) {
+	case MEDIA_BUS_FMT_UYYVYY8_0_5X24:
+	case MEDIA_BUS_FMT_UYYVYY10_0_5X30:
+	case MEDIA_BUS_FMT_UYYVYY12_0_5X36:
+	case MEDIA_BUS_FMT_UYYVYY16_0_5X48:
+		return true;
+
+	default:
+		return false;
+	}
+}
+
 static int hdmi_bus_fmt_color_depth(unsigned int bus_format)
 {
 	switch (bus_format) {
@@ -877,7 +892,8 @@ static void hdmi_video_packetize(struct dw_hdmi *hdmi)
 	u8 val, vp_conf;
 
 	if (hdmi_bus_fmt_is_rgb(hdmi->hdmi_data.enc_out_bus_format) ||
-	    hdmi_bus_fmt_is_yuv444(hdmi->hdmi_data.enc_out_bus_format)) {
+	    hdmi_bus_fmt_is_yuv444(hdmi->hdmi_data.enc_out_bus_format) ||
+	    hdmi_bus_fmt_is_yuv420(hdmi->hdmi_data.enc_out_bus_format)) {
 		switch (hdmi_bus_fmt_color_depth(
 					hdmi->hdmi_data.enc_out_bus_format)) {
 		case 8:
@@ -1018,7 +1034,7 @@ EXPORT_SYMBOL_GPL(dw_hdmi_phy_i2c_write);
 
 void dw_hdmi_set_high_tmds_clock_ratio(struct dw_hdmi *hdmi)
 {
-	unsigned long mtmdsclock = hdmi->hdmi_data.video_mode.mpixelclock;
+	unsigned long mtmdsclock = hdmi->hdmi_data.video_mode.mtmdsclock;
 
 	/* Control for TMDS Bit Period/TMDS Clock-Period Ratio */
 	if (hdmi->connector.display_info.hdmi.scdc.supported) {
@@ -1359,6 +1375,9 @@ static void hdmi_config_AVI(struct dw_hdmi *hdmi, struct drm_display_mode *mode)
 	struct hdmi_avi_infoframe frame;
 	u8 val;
 
+	if (hdmi_bus_fmt_is_yuv420(hdmi->hdmi_data.enc_out_bus_format))
+		is_hdmi2_sink = true;
+
 	/* Initialise info frame from DRM mode */
 	drm_hdmi_avi_infoframe_from_display_mode(&frame, mode, is_hdmi2_sink);
 
@@ -1366,6 +1385,8 @@ static void hdmi_config_AVI(struct dw_hdmi *hdmi, struct drm_display_mode *mode)
 		frame.colorspace = HDMI_COLORSPACE_YUV444;
 	else if (hdmi_bus_fmt_is_yuv422(hdmi->hdmi_data.enc_out_bus_format))
 		frame.colorspace = HDMI_COLORSPACE_YUV422;
+	else if (hdmi_bus_fmt_is_yuv420(hdmi->hdmi_data.enc_out_bus_format))
+		frame.colorspace = HDMI_COLORSPACE_YUV420;
 	else
 		frame.colorspace = HDMI_COLORSPACE_RGB;
 
@@ -1523,15 +1544,18 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
 	struct drm_hdmi_info *hdmi_info = &hdmi->connector.display_info.hdmi;
 	struct hdmi_vmode *vmode = &hdmi->hdmi_data.video_mode;
 	int hblank, vblank, h_de_hs, v_de_vs, hsync_len, vsync_len;
-	unsigned int vdisplay;
+	unsigned int vdisplay, hdisplay;
 
-	vmode->mpixelclock = mode->clock * 1000;
+	vmode->mtmdsclock = vmode->mpixelclock = mode->clock * 1000;
 
 	dev_dbg(hdmi->dev, "final pixclk = %d\n", vmode->mpixelclock);
 
+	if (hdmi_bus_fmt_is_yuv420(hdmi->hdmi_data.enc_out_bus_format))
+		vmode->mtmdsclock /= 2;
+
 	/* Set up HDMI_FC_INVIDCONF */
 	inv_val = (hdmi->hdmi_data.hdcp_enable ||
-		   vmode->mpixelclock > 340000000 ||
+		   vmode->mtmdsclock > 340000000 ||
 		   hdmi_info->scdc.scrambling.low_rates ?
 		HDMI_FC_INVIDCONF_HDCP_KEEPOUT_ACTIVE :
 		HDMI_FC_INVIDCONF_HDCP_KEEPOUT_INACTIVE);
@@ -1565,6 +1589,22 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
 
 	hdmi_writeb(hdmi, inv_val, HDMI_FC_INVIDCONF);
 
+	hdisplay = mode->hdisplay;
+	hblank = mode->htotal - mode->hdisplay;
+	h_de_hs = mode->hsync_start - mode->hdisplay;
+	hsync_len = mode->hsync_end - mode->hsync_start;
+
+	/*
+	 * When we're setting a YCbCr420 mode, we need
+	 * to adjust the horizontal timing to suit.
+	 */
+	if (hdmi_bus_fmt_is_yuv420(hdmi->hdmi_data.enc_out_bus_format)) {
+		hdisplay /= 2;
+		hblank /= 2;
+		h_de_hs /= 2;
+		hsync_len /= 2;
+	}
+
 	vdisplay = mode->vdisplay;
 	vblank = mode->vtotal - mode->vdisplay;
 	v_de_vs = mode->vsync_start - mode->vdisplay;
@@ -1583,7 +1623,7 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
 
 	/* Scrambling Control */
 	if (hdmi_info->scdc.supported) {
-		if (vmode->mpixelclock > 340000000 ||
+		if (vmode->mtmdsclock > 340000000 ||
 		    hdmi_info->scdc.scrambling.low_rates) {
 			drm_scdc_readb(&hdmi->i2c->adap, SCDC_SINK_VERSION,
 				       &bytes);
@@ -1602,15 +1642,14 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
 	}
 
 	/* Set up horizontal active pixel width */
-	hdmi_writeb(hdmi, mode->hdisplay >> 8, HDMI_FC_INHACTV1);
-	hdmi_writeb(hdmi, mode->hdisplay, HDMI_FC_INHACTV0);
+	hdmi_writeb(hdmi, hdisplay >> 8, HDMI_FC_INHACTV1);
+	hdmi_writeb(hdmi, hdisplay, HDMI_FC_INHACTV0);
 
 	/* Set up vertical active lines */
 	hdmi_writeb(hdmi, vdisplay >> 8, HDMI_FC_INVACTV1);
 	hdmi_writeb(hdmi, vdisplay, HDMI_FC_INVACTV0);
 
 	/* Set up horizontal blanking pixel region width */
-	hblank = mode->htotal - mode->hdisplay;
 	hdmi_writeb(hdmi, hblank >> 8, HDMI_FC_INHBLANK1);
 	hdmi_writeb(hdmi, hblank, HDMI_FC_INHBLANK0);
 
@@ -1618,7 +1657,6 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
 	hdmi_writeb(hdmi, vblank, HDMI_FC_INVBLANK);
 
 	/* Set up HSYNC active edge delay width (in pixel clks) */
-	h_de_hs = mode->hsync_start - mode->hdisplay;
 	hdmi_writeb(hdmi, h_de_hs >> 8, HDMI_FC_HSYNCINDELAY1);
 	hdmi_writeb(hdmi, h_de_hs, HDMI_FC_HSYNCINDELAY0);
 
@@ -1626,7 +1664,6 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
 	hdmi_writeb(hdmi, v_de_vs, HDMI_FC_VSYNCINDELAY);
 
 	/* Set up HSYNC active pulse width (in pixel clks) */
-	hsync_len = mode->hsync_end - mode->hsync_start;
 	hdmi_writeb(hdmi, hsync_len >> 8, HDMI_FC_HSYNCINWIDTH1);
 	hdmi_writeb(hdmi, hsync_len, HDMI_FC_HSYNCINWIDTH0);
 
-- 
2.19.1