Re: [PATCH] drm: support gpu aliases defined in DT data

From: Tomi Valkeinen <tomi.valkeinen@ti.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Mark Rutland <mark.rutland@arm.com>,
	devicetree@vger.kernel.org,
	Maxime Ripard <maxime.ripard@bootlin.com>,
	Frank Rowand <frowand.list@gmail.com>,
	dri-devel <dri-devel@lists.freedesktop.org>,
	David Airlie <airlied@linux.ie>,
	Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
	Rob Herring <robh+dt@kernel.org>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Sean Paul <sean@poorly.run>
Subject: Re: [PATCH] drm: support gpu aliases defined in DT data
Date: Thu, 17 Jan 2019 15:56:32 +0200	[thread overview]
Message-ID: <f151e774-96b5-56b5-1aaa-f51f9ac09e1e@ti.com> (raw)
In-Reply-To: <CAKMK7uEUhPtmyujMGb-YNbrhYM9tqVc2S+=cJFWQvQOeSRaSnw@mail.gmail.com>

On 17/01/19 15:26, Daniel Vetter wrote:
> On Thu, Jan 17, 2019 at 2:04 PM Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
>>
>> On 17/01/19 14:33, Daniel Vetter wrote:
>>> On Thu, Jan 17, 2019 at 01:19:18PM +0200, Tomi Valkeinen wrote:
>>>> The DRM device minor numbers are allocated according to the registration
>>>> order. This causes confusion in cases where the registration order can
>>>> change, or when, say, a modesetting capable device is preferred to be
>>>> card0, and a rendering device is preferred to be card1.
>>>>
>>>> This patch adds similar functionality that is used in some other
>>>> subsystems, where device minor numbers can be defined in DT bindings'
>>>> aliases node.
>>>
>>> What other subsystem? I thought that minor numbers shouldn't be made uapi,
>>> and that udev or similar is supposed to give you stable names ... Is that
>>> not the case on SoC?
>>
>> I think at least i2c, spi and uart use DT aliases.
> 
> Commits/code implementing would be best.

For i2c:

ee5c27440cc24d62ec463cce4c000bb32c5692c7
("i2c: core: Pick i2c bus number from dt alias if present")

03bde7c31a360f814ca42101d60563b1b803dca1
("i2c: busses with dynamic ids should start after fixed ids for DT")

>> I also have my doubts about this, but thought to post this to get some
>> comments, as it does make life quite a bit easier =).
> 
> Yeah I think "soc without udev" seems reasonable assumption, I just

I'm not that familiar with udev rules. I wonder how it would work... The
rule would need to keep all dynamic cards out from the group of reserved
card names, and also handle render nodes. All this is probably possible,
with a quick study I could find out how to implement something like that.

> think this is something the overall soc community should agree on as a
> good thing to do. I guess since the of stuff you're using is generic
> that's all happened already, so should amount to gathering a pile of
> acks and then merging it.

Ok. I'm not sure who the "SoC people" would be, but I added some more OF
people here.

 Tomi

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