linux-kernel - Re: [PATCH] drm: bridge: dw-hdmi: Avoid resetting force in the detect function

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Message-ID: <20201112212254.GA3361340@ravnborg.org>
Date:   Thu, 12 Nov 2020 22:22:54 +0100
From:   Sam Ravnborg <sam@...nborg.org>
To:     Jonathan Liu <net147@...il.com>
Cc:     linux-rockchip@...ts.infradead.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Fabio Estevam <fabio.estevam@...escale.com>,
        Jernej Skrabec <jernej.skrabec@...l.net>,
        Jonas Karlman <jonas@...boo.se>,
        David Airlie <airlied@...ux.ie>,
        Neil Armstrong <narmstrong@...libre.com>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Boris Brezillon <boris.brezillon@...labora.com>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Russell King <rmk+kernel@....linux.org.uk>,
        Liu Ying <victor.liu@....com>
Subject: Re: [PATCH] drm: bridge: dw-hdmi: Avoid resetting force in the
 detect function

Hi Jonathan
On Sat, Oct 31, 2020 at 07:17:47PM +1100, Jonathan Liu wrote:
> 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@...il.com>

Applied to drm-misc-fixes.

	Sam