Subject: Re: [PATCH] um: virtio_uml: allow probing from devicetree
To:     Vincent Whitchurch <vincent.whitchurch@axis.com>,
        Johannes Berg <johannes@sipsolutions.net>
Cc:     Jeff Dike <jdike@addtoit.com>, Richard Weinberger <richard@nod.at>,
        Rob Herring <robh+dt@kernel.org>, kernel <kernel@axis.com>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
        "linux-um@lists.infradead.org" <linux-um@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20211221090447.1567-1-vincent.whitchurch@axis.com>
 <5f104044649ec60ba93648e68c3df2183e032072.camel@sipsolutions.net>
 <20211222103417.GB25135@axis.com>
From:   Anton Ivanov <anton.ivanov@cambridgegreys.com>
Message-ID: <a862c00c-0db4-e2b7-4ee7-958f3bdd856e@cambridgegreys.com>
Date:   Tue, 4 Jan 2022 14:13:25 +0000
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On 22/12/2021 10:34, Vincent Whitchurch wrote:
> On Tue, Dec 21, 2021 at 09:48:26PM +0100, Johannes Berg wrote:
>> On Tue, 2021-12-21 at 10:04 +0100, Vincent Whitchurch wrote:
>>> Allow the virtio_uml device to be probed from the devicetree so that
>>> sub-devices can be specified using the standard virtio bindings, for
>>> example:
>>>
>>>    virtio@1 {
>>>      compatible = "virtio,uml";
>>>      socket-path = "i2c.sock";
>>>      virtio-device-id = <0x22>;
>>>
>>
>> Given this, maybe it should modify
>> Documentation/devicetree/bindings/virtio/virtio-device.yaml? Or actually
>> add a new Documentation/devicetree/bindings/virtio/uml.yaml I guess?
>>
>> +Rob, because I'm not really into any of this.
>>
>> Also, I'm not even sure we should/need to document the DT bits that are
>> basically only used for testing in the first place?

If we start adding the UML devices themselves to the DT, we might as well add all of them.

In the doc patch have described the DT support as mostly for development at this point.

It can be a good alternative to the endless command line (especially for complex devices like f.e. l2tpv3).


> 
> I wasn't sure either, but Rob was OK with not documenting some other
> bindings which are only used for testing[0], so I assumed that that
> applied here too:
> 
>   [0] https://lore.kernel.org/all/5baa1ae6.1c69fb81.847f2.3ab1@mx.google.com/
> 
> Also, DT bindings are supposed to be generic and based on what the
> hardware has, but here we have no hardware and something very Linux and
> UML-specific.
> 
>> Code looks good to me.
> 
> Thanks!
> 

Brgds,

-- 
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
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