drm/bridge: dw-hdmi: Restore audio when setting a mode

[ Upstream commit fadfee3f9d8f114435a8a3e9f83a227600d89de7 ]

When setting a new display mode, dw_hdmi_setup() calls
dw_hdmi_enable_video_path(), which disables all hdmi clocks, including
the audio clock.

We should only (re-)enable the audio clock if audio was already enabled
when setting the new mode.

Without this patch, on RK3288, there will be HDMI audio on some monitors
if i2s was played to headphone when the monitor was plugged.
ACER H277HU and ASUS PB278 are two of the monitors showing this issue.
Signed-off-by: NCheng-Yi Chiang <cychiang@chromium.org>
Signed-off-by: NDaniel Kurtz <djkurtz@chromium.org>
Signed-off-by: NYakir Yang <ykk@rock-chips.com>
Reviewed-by: NNeil Armstrong <narmstrong@baylibre.com>
Signed-off-by: NNeil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191008102145.55134-1-cychiang@chromium.orgSigned-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/gpu/drm/bridge/synopsys/dw-hdmi.c

@@ -1757,7 +1757,7 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi, struct drm_display_mode *mode)
 
 		/* HDMI Initialization Step E - Configure audio */
 		hdmi_clk_regenerator_update_pixel_clock(hdmi);
-		hdmi_enable_audio_clk(hdmi, true);
+		hdmi_enable_audio_clk(hdmi, hdmi->audio_enable);
 	}
 
 	/* not for DVI mode */