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);

 }