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From: Jonathan Liu <net147@gmail.com>
To: linux-rockchip@lists.infradead.org,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Cc: Fabio Estevam <fabio.estevam@freescale.com>,
	Jernej Skrabec <jernej.skrabec@siol.net>,
	Jonas Karlman <jonas@kwiboo.se>, David Airlie <airlied@linux.ie>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Jonathan Liu <net147@gmail.com>,
	Andrzej Hajda <a.hajda@samsung.com>,
	Boris Brezillon <boris.brezillon@collabora.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Daniel Vetter <daniel@ffwll.ch>,
	Russell King <rmk+kernel@arm.linux.org.uk>,
	Liu Ying <victor.liu@nxp.com>, Sam Ravnborg <sam@ravnborg.org>
Subject: [PATCH] drm: bridge: dw-hdmi: Avoid resetting force in the detect function
Date: Sat, 31 Oct 2020 19:17:47 +1100	[thread overview]
Message-ID: <20201031081747.372599-1-net147@gmail.com> (raw)

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>
---
 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 748df1cacd2b..0c79a9ba48bb 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);
-- 
2.29.1


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             reply	other threads:[~2020-10-31  8:19 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-31  8:17 Jonathan Liu [this message]
2020-11-08  9:53 ` [PATCH] drm: bridge: dw-hdmi: Avoid resetting force in the detect function Sam Ravnborg
2020-11-08  9:57   ` Russell King - ARM Linux admin
2020-11-08 10:47     ` Sam Ravnborg
2020-11-11  7:59       ` Jonathan Liu
2020-11-12 21:22 ` Sam Ravnborg

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