linux-kernel - Re: [PATCH v11 1/9] device property: Add remote endpoint to devcon matcher

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Date:   Thu, 9 Feb 2023 10:24:59 +0200
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Pin-yen Lin <treapking@...omium.org>
Cc:     Andrzej Hajda <andrzej.hajda@...el.com>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jonas Karlman <jonas@...boo.se>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Daniel Scally <djrscally@...il.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Prashant Malani <pmalani@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        linux-kernel@...r.kernel.org,
        Nícolas F . R . A . Prado 
        <nfraprado@...labora.com>, Hsin-Yi Wang <hsinyi@...omium.org>,
        devicetree@...r.kernel.org, Allen Chen <allen.chen@....com.tw>,
        Lyude Paul <lyude@...hat.com>, linux-acpi@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, Marek Vasut <marex@...x.de>,
        Xin Ji <xji@...logixsemi.com>,
        Stephen Boyd <swboyd@...omium.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Javier Martinez Canillas <javierm@...hat.com>,
        chrome-platform@...ts.linux.dev, Chen-Yu Tsai <wenst@...omium.org>
Subject: Re: [PATCH v11 1/9] device property: Add remote endpoint to devcon
 matcher

Hi Pin-yen,

On Thu, Feb 09, 2023 at 12:28:33PM +0800, Pin-yen Lin wrote:
> Hi Sakari,
> 
> Thanks for the review.
> 
> On Mon, Feb 6, 2023 at 5:11 AM Sakari Ailus
> <sakari.ailus@...ux.intel.com> wrote:
> >
> > Hi Pin-yen,
> >
> > On Sat, Feb 04, 2023 at 09:30:32PM +0800, Pin-yen Lin wrote:
> > > From: Prashant Malani <pmalani@...omium.org>
> > >
> > > When searching the device graph for device matches, check the
> > > remote-endpoint itself for a match.
> > >
> > > Some drivers register devices for individual endpoints. This allows
> > > the matcher code to evaluate those for a match too, instead
> > > of only looking at the remote parent devices. This is required when a
> > > device supports two mode switches in its endpoints, so we can't simply
> > > register the mode switch with the parent node.
> > >
> > > Signed-off-by: Prashant Malani <pmalani@...omium.org>
> > > Signed-off-by: Pin-yen Lin <treapking@...omium.org>
> > > Reviewed-by: Chen-Yu Tsai <wenst@...omium.org>
> > > Tested-by: Chen-Yu Tsai <wenst@...omium.org>
> >
> > Thanks for the update.
> >
> > I intended to give my Reviewed-by: but there's something still needs to be
> > addressed. See below.
> >
> > >
> > > ---
> > >
> > > Changes in v11:
> > > - Added missing fwnode_handle_put in drivers/base/property.c
> > >
> > > Changes in v10:
> > > - Collected Reviewed-by and Tested-by tags
> > >
> > > Changes in v6:
> > > - New in v6
> > >
> > >  drivers/base/property.c | 16 ++++++++++++++++
> > >  1 file changed, 16 insertions(+)
> > >
> > > diff --git a/drivers/base/property.c b/drivers/base/property.c
> > > index 2a5a37fcd998..e6f915b72eb7 100644
> > > --- a/drivers/base/property.c
> > > +++ b/drivers/base/property.c
> > > @@ -1223,6 +1223,22 @@ static unsigned int fwnode_graph_devcon_matches(struct fwnode_handle *fwnode,
> > >                       break;
> > >               }
> > >
> > > +             /*
> > > +              * Some drivers may register devices for endpoints. Check
> > > +              * the remote-endpoints for matches in addition to the remote
> > > +              * port parent.
> > > +              */
> > > +             node = fwnode_graph_get_remote_endpoint(ep);
> >
> > Here fwnode_graph_get_remote_endpoint() returns an endpoint...
> >
> > > +             if (fwnode_device_is_available(node)) {
> >
> > and you're calling fwnode_device_is_available() on the endpoint node, which
> > always returns true.
> >
> > Shouldn't you call this on the device node instead? What about match()
> > below?
> 
> Yes we should have checked the availability on the device node itself
> instead of the endpoint node. But regarding the match() call, we need
> to call it with the endpoint node because that's where we put the
> "mode-switch" properties and register the mode switches on. We can't
> use the device node because we want to register two mode switches for
> the same device node.

Ok.

I think it should be documented for both fwnode_connection_find_match() and
fwnode_connection_find_matches() may then be also called with the endpoint
node.

-- 
Regards,

Sakari Ailus