drm/mediatek: Disable tmds on mt2701

Without that patch if you use specific resolutions like 1280x1024,
I can see distortion in the output. It seems as if the
frequency for updating the pixel of the image is out of sync.

For initialization tmds needs to be active, but can be disabled after init
to fix blurry display
Signed-off-by: chunhui dai <chunhui.dai@mediatek.com>
Signed-off-by: Frank Wunderlich <frank-w@public-files.de>
Tested-by: Frank Wunderlich <frank-w@public-files.de>
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

drivers/phy/mediatek/phy-mtk-hdmi-mt2701.c

@@ -238,6 +238,7 @@ static void mtk_hdmi_phy_disable_tmds(struct mtk_hdmi_phy *hdmi_phy)
 
 struct mtk_hdmi_phy_conf mtk_hdmi_phy_2701_conf = {
 	.flags = CLK_SET_RATE_GATE,
+	.pll_default_off = true,
 	.hdmi_phy_clk_ops = &mtk_hdmi_phy_pll_ops,
 	.hdmi_phy_enable_tmds = mtk_hdmi_phy_enable_tmds,
 	.hdmi_phy_disable_tmds = mtk_hdmi_phy_disable_tmds,

drivers/phy/mediatek/phy-mtk-hdmi.c

@@ -184,6 +184,9 @@ static int mtk_hdmi_phy_probe(struct platform_device *pdev)
 		return PTR_ERR(phy_provider);
 	}
 
+	if (hdmi_phy->conf->pll_default_off)
+		hdmi_phy->conf->hdmi_phy_disable_tmds(hdmi_phy);
+
 	return of_clk_add_provider(dev->of_node, of_clk_src_simple_get,
 				   hdmi_phy->pll);
 }

drivers/phy/mediatek/phy-mtk-hdmi.h

@@ -21,6 +21,7 @@ struct mtk_hdmi_phy;
 
 struct mtk_hdmi_phy_conf {
 	unsigned long flags;
+	bool pll_default_off;
 	const struct clk_ops *hdmi_phy_clk_ops;
 	void (*hdmi_phy_enable_tmds)(struct mtk_hdmi_phy *hdmi_phy);
 	void (*hdmi_phy_disable_tmds)(struct mtk_hdmi_phy *hdmi_phy);