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

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Date:   Sun, 8 Nov 2020 10:53:22 +0100
From:   Sam Ravnborg <sam@...nborg.org>
To:     Jonathan Liu <net147@...il.com>,
        Russell King <rmk+kernel@....linux.org.uk>
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

Russell,

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>

you are the original author of this code - any comments on this patch?

	Sam

> ---
>  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
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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