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

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Date:   Sun, 5 Feb 2023 23:11:34 +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 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?

> +			ret = match(node, con_id, data);
> +			if (ret) {
> +				if (matches)
> +					matches[count] = ret;
> +				count++;
> +			}
> +		}
> +		fwnode_handle_put(node);
> +
>  		node = fwnode_graph_get_remote_port_parent(ep);
>  		if (!fwnode_device_is_available(node)) {
>  			fwnode_handle_put(node);

-- 
Kind regards,

Sakari Ailus