From 5e1bc251cebc84b41b8eb5d2434e54d939a85430 Mon Sep 17 00:00:00 2001
From: Priit Laes <priit.laes@paf.com>
Date: Tue, 22 Jan 2019 09:32:32 +0200
Subject: drm/sun4i: hdmi: Fix usage of TMDS clock
Git-commit: 5e1bc251cebc84b41b8eb5d2434e54d939a85430
Patch-mainline: v5.0-rc4
References: bsc#1113956

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
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_enc.c
index 061d2e0d9011..416da5376701 100644
--- 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);
-- 
2.20.1