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Subject: Re: 'bad remote port parent' warnings
To: Fabio Estevam <festevam@gmail.com>,
        Philipp Zabel <p.zabel@pengutronix.de>
Cc: Sakari Ailus <sakari.ailus@linux.intel.com>,
        Hans Verkuil <hverkuil@xs4all.nl>,
        linux-media <linux-media@vger.kernel.org>
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From: Steve Longerbeam <slongerbeam@gmail.com>
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Date: Fri, 23 Nov 2018 14:37:54 -0800
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Hi Fabio,

On 11/22/18 11:17 AM, Fabio Estevam wrote:
> Hi Philipp,
>
> On Thu, Nov 22, 2018 at 2:27 PM Philipp Zabel <p.zabel@pengutronix.de> wrote:
>
>> There are empty endpoint nodes (without remote-endpoint property)
>> labeled ipu1_csi[01]_mux_from_parallel_sensor in the i.MX6 device trees
>> for board DT implementers' convenience. See commit 2539f517acbdc ("ARM:
>> dts: imx6qdl: Add video multiplexers, mipi_csi, and their connections").
>>
>> We had a discussion about this issue in February when this caused a
>> probing error: https://patchwork.kernel.org/patch/10234469/
> Thanks for the clarification.
>
>   We could demote the warning to a debug message, make the wording a bit
>> less misleading (there is no bad remote port parent, there is just no
>> remote endpoint at all), or we could just accept the error message for
> Something like this?
>
> --- a/drivers/media/v4l2-core/v4l2-fwnode.c
> +++ b/drivers/media/v4l2-core/v4l2-fwnode.c
> @@ -613,7 +613,7 @@ v4l2_async_notifier_fwnode_parse_endpoint(struct
> device *dev,
>          asd->match.fwnode =
>                  fwnode_graph_get_remote_port_parent(endpoint);
>          if (!asd->match.fwnode) {
> -               dev_warn(dev, "bad remote port parent\n");
> +               dev_dbg(dev, "no remote endpoint found\n");
>                  ret = -ENOTCONN;
>                  goto out_err;
>          }
>
> And how should we treat these error probes?
>
> [    3.449564] imx-ipuv3 2400000.ipu: driver could not parse
> port@1/endpoint@0 (-22)
> [    3.457342] imx-ipuv3-csi: probe of imx-ipuv3-csi.1 failed with error -22
> [    3.464498] imx-ipuv3 2800000.ipu: driver could not parse
> port@0/endpoint@0 (-22)
> [    3.472120] imx-ipuv3-csi: probe of imx-ipuv3-csi.4 failed with error -22

Yes, this is a regression caused by the imx subdev notifier patches. 
I've already sent a patch to the list for this, see

https://www.spinics.net/lists/linux-media/msg141809.html

Steve