[PATCH 5.9 125/252] drm: bridge: dw-hdmi: Avoid resetting force in the detect function

Greg Kroah-Hartman
2020-11-23T12:49:44Z

From: Jonathan Liu <net147@gmail.com>

[ Upstream commit bc551d776b691022f49b5bb5379bd58f7c4eb76a ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 6 ------
1 file changed, 6 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index 748df1cacd2b7..0c79a9ba48bb6 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -2327,12 +2327,6 @@ static enum drm_connector_status dw_hdmi_detect(struct dw_hdmi *hdmi)
{
enum drm_connector_status result;

- mutex_lock(&hdmi->mutex);
- hdmi->force = DRM_FORCE_UNSPECIFIED;
- dw_hdmi_update_power(hdmi);
- dw_hdmi_update_phy_mask(hdmi);
- mutex_unlock(&hdmi->mutex);
-
result = hdmi->phy.ops->read_hpd(hdmi, hdmi->phy.data);

mutex_lock(&hdmi->mutex);
--
2.27.0