From bc551d776b691022f49b5bb5379bd58f7c4eb76a Mon Sep 17 00:00:00 2001
From: Jonathan Liu <net147@gmail.com>
Date: Sat, 31 Oct 2020 19:17:47 +1100
Subject: drm: bridge: dw-hdmi: Avoid resetting force in the detect function
Git-commit: bc551d776b691022f49b5bb5379bd58f7c4eb76a
Patch-mainline: v5.10-rc5
References: bsc#1129770

It has been observed that resetting force in the detect function can
result in the PHY being powered down in response to hot-plug detect
being asserted, even when the HDMI connector is forced on.

Enabling debug messages and adding a call to dump_stack() in
dw_hdmi_phy_power_off() shows the following in dmesg:
[  160.637413] dwhdmi-rockchip ff940000.hdmi: EVENT=plugin
[  160.637433] dwhdmi-rockchip ff940000.hdmi: PHY powered down in 0 iterations

Call trace:
dw_hdmi_phy_power_off
dw_hdmi_phy_disable
dw_hdmi_update_power
dw_hdmi_detect
dw_hdmi_connector_detect
drm_helper_probe_detect_ctx
drm_helper_hpd_irq_event
dw_hdmi_irq
irq_thread_fn
irq_thread
kthread
ret_from_fork

Fixes: 381f05a7a842 ("drm: bridge/dw_hdmi: add connector mode forcing")
Signed-off-by: Jonathan Liu <net147@gmail.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201031081747.372599-1-net147@gmail.com
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.c |    6 ------
 1 file changed, 6 deletions(-)

--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -1906,12 +1906,6 @@ dw_hdmi_connector_detect(struct drm_conn
 	struct dw_hdmi *hdmi = container_of(connector, struct dw_hdmi,
 					     connector);
 
-	mutex_lock(&hdmi->mutex);
-	hdmi->force = DRM_FORCE_UNSPECIFIED;
-	dw_hdmi_update_power(hdmi);
-	dw_hdmi_update_phy_mask(hdmi);
-	mutex_unlock(&hdmi->mutex);
-
 	return hdmi->phy.ops->read_hpd(hdmi, hdmi->phy.data);
 }