linux-kernel - Re: [PATCH 3/4] drm/bridge: lt8912b: Manually disable HPD only if it was enabled

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Message-ID: <cb069b10a38b018868f370fada3e97da7257264b.camel@toradex.com>
Date:   Mon, 4 Sep 2023 18:08:12 +0000
From:   Marcel Ziswiler <marcel.ziswiler@...adex.com>
To:     "Laurent.pinchart@...asonboard.com" 
        <Laurent.pinchart@...asonboard.com>,
        "andrzej.hajda@...el.com" <andrzej.hajda@...el.com>,
        "neil.armstrong@...aro.org" <neil.armstrong@...aro.org>,
        Stefan Eichenberger <stefan.eichenberger@...adex.com>,
        "tomi.valkeinen@...asonboard.com" <tomi.valkeinen@...asonboard.com>,
        "adrien.grassein@...il.com" <adrien.grassein@...il.com>,
        "rfoss@...nel.org" <rfoss@...nel.org>,
        "airlied@...il.com" <airlied@...il.com>,
        Francesco Dolcini <francesco.dolcini@...adex.com>,
        "jonas@...boo.se" <jonas@...boo.se>,
        "jernej.skrabec@...il.com" <jernej.skrabec@...il.com>,
        "daniel@...ll.ch" <daniel@...ll.ch>
CC:     "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 3/4] drm/bridge: lt8912b: Manually disable HPD only if it
 was enabled

Hi Tomi

Looks good. Thanks! Tested both on Verdin AM62 as well as on Verdin iMX8M Mini.

Just a minor nit-pick in your commit message.

On Fri, 2023-08-04 at 13:48 +0300, Tomi Valkeinen wrote:
> lt8912b only calls drm_bridge_hpd_enable() if it creates a connector and
> the next bridge has DRM_BRIDGE_OP_HPD set. However, when calling
> drm_bridge_hpd_disable() it misses checking if a connector was created,
> calling drm_bridge_hpd_disable() even if HPD was nenver enabled. I don't

was never enabled

> see any issues causing by this wrong call, though.

any issues caused by this wrong call

> Add the check to avoid wrongly calling drm_bridge_hpd_disable().
> 
> Fixes: 3b0a01a6a522 ("drm/bridge: lt8912b: Add hot plug detection")
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>

For the whole series:

Tested-by: Marcel Ziswiler <marcel.ziswiler@...adex.com>

> ---
>  drivers/gpu/drm/bridge/lontium-lt8912b.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/bridge/lontium-lt8912b.c b/drivers/gpu/drm/bridge/lontium-lt8912b.c
> index 2d752e083433..9ee639e75a1c 100644
> --- a/drivers/gpu/drm/bridge/lontium-lt8912b.c
> +++ b/drivers/gpu/drm/bridge/lontium-lt8912b.c
> @@ -587,7 +587,7 @@ static void lt8912_bridge_detach(struct drm_bridge *bridge)
>  
>         lt8912_hard_power_off(lt);
>  
> -       if (lt->hdmi_port->ops & DRM_BRIDGE_OP_HPD)
> +       if (lt->connector.dev && lt->hdmi_port->ops & DRM_BRIDGE_OP_HPD)
>                 drm_bridge_hpd_disable(lt->hdmi_port);
>  }

Cheers

Marcel