Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Message-ID: <54c01a13f382aacd7cd4d75a642630053f54b8f1.camel@redhat.com>
Subject: Re: [PATCH] drm/probe_helper: Don't bother probing when connectors
 are forced off
From:   Lyude Paul <lyude@redhat.com>
Reply-To: lyude@redhat.com
To:     Ville =?ISO-8859-1?Q?Syrj=E4l=E4?= <ville.syrjala@linux.intel.com>
Cc:     dri-devel@lists.freedesktop.org, Sean Paul <sean@poorly.run>,
        David Airlie <airlied@linux.ie>, linux-kernel@vger.kernel.org
Date:   Mon, 17 Sep 2018 14:10:02 -0400
In-Reply-To: <20180917175545.GP5565@intel.com>
References: <20180917174344.22011-1-lyude@redhat.com>
         <20180917175545.GP5565@intel.com>
Organization: Red Hat
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, 2018-09-17 at 20:55 +0300, Ville Syrjälä wrote:
> On Mon, Sep 17, 2018 at 01:43:44PM -0400, Lyude Paul wrote:
> > Userspace asked them to be forced off, so why would we care about what a
> > probe tells us?
> 
> I believe there should be force checks in the callers already.
> Or are we missing some?

JFYI, what triggered me to send this patch are these error messages that come
from nouveau when a hotplug happens on a port that we've forced off:

[ 1903.918104] nouveau 0000:01:00.0: DRM: DDC responded, but no EDID for DP-2
[ 1903.918123] [drm:drm_helper_hpd_irq_event [drm_kms_helper]] [CONNECTOR:61:DP-2] status updated from disconnected to disconnected

That being said; I'm sure there are probably some checks missing, but I don't
really see the purpose in calling the driver's probe functions at all if they're
just supposed to return the status we forced.

> 
> > 
> > Signed-off-by: Lyude Paul <lyude@redhat.com>
> > ---
> >  drivers/gpu/drm/drm_probe_helper.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/drm_probe_helper.c
> > b/drivers/gpu/drm/drm_probe_helper.c
> > index a1bb157bfdfa..56d2b5dd1f58 100644
> > --- a/drivers/gpu/drm/drm_probe_helper.c
> > +++ b/drivers/gpu/drm/drm_probe_helper.c
> > @@ -269,7 +269,9 @@ drm_helper_probe_detect_ctx(struct drm_connector
> > *connector, bool force)
> >  retry:
> >  	ret = drm_modeset_lock(&connector->dev->mode_config.connection_mutex,
> > &ctx);
> >  	if (!ret) {
> > -		if (funcs->detect_ctx)
> > +		if (connector->force == DRM_FORCE_OFF)
> > +			ret = connector_status_disconnected;
> 
> connector->force is protected by mode_config.mutex IIRC.
> 
> > +		else if (funcs->detect_ctx)
> >  			ret = funcs->detect_ctx(connector, &ctx, force);
> >  		else if (connector->funcs->detect)
> >  			ret = connector->funcs->detect(connector, force);
> > @@ -317,6 +319,9 @@ drm_helper_probe_detect(struct drm_connector *connector,
> >  	if (ret)
> >  		return ret;
> >  
> > +	if (connector->force == DRM_FORCE_OFF)
> > +		return connector_status_disconnected;
> > +
> >  	if (funcs->detect_ctx)
> >  		return funcs->detect_ctx(connector, ctx, force);
> >  	else if (connector->funcs->detect)
> > -- 
> > 2.17.1
> > 
> > _______________________________________________
> > dri-devel mailing list
> > dri-devel@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
>