drm/sun4i: hdmi: Fix usage of TMDS clock

[ Upstream commit 5e1bc251cebc84b41b8eb5d2434e54d939a85430 ]

Although TMDS clock is required for HDMI to properly function,
nobody called clk_prepare_enable(). This fixes reference counting
issues and makes sure clock is running when it needs to be running.

Due to TDMS clock being parent clock for DDC clock, TDMS clock
was turned on/off for each EDID probe, causing spurious failures
for certain HDMI/DVI screens.

Fixes: 9c5681011a0c ("drm/sun4i: Add HDMI support")
Signed-off-by: Priit Laes <priit.laes@paf.com>
[Maxime: Moved the TMDS clock enable earlier]
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190122073232.7240-1-plaes@plaes.org
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
index 061d2e0d9011ee88991b3f0fb1b4e2dd54925bee..416da53767018ca9acbcef98689c173af0732fca 100644 (file)
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
@@ -92,6 +92,8 @@ static void sun4i_hdmi_disable(struct drm_encoder *encoder)
        val = readl(hdmi->base + SUN4I_HDMI_VID_CTRL_REG);
        val &= ~SUN4I_HDMI_VID_CTRL_ENABLE;
        writel(val, hdmi->base + SUN4I_HDMI_VID_CTRL_REG);
+
+       clk_disable_unprepare(hdmi->tmds_clk);
 }
 
 static void sun4i_hdmi_enable(struct drm_encoder *encoder)
@@ -102,6 +104,8 @@ static void sun4i_hdmi_enable(struct drm_encoder *encoder)
 
        DRM_DEBUG_DRIVER("Enabling the HDMI Output\n");
 
+       clk_prepare_enable(hdmi->tmds_clk);
+
        sun4i_hdmi_setup_avi_infoframes(hdmi, mode);
        val |= SUN4I_HDMI_PKT_CTRL_TYPE(0, SUN4I_HDMI_PKT_AVI);
        val |= SUN4I_HDMI_PKT_CTRL_TYPE(1, SUN4I_HDMI_PKT_END);