Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [Q] devicetree overlays
To:     Sven Van Asbroeck <thesven73@gmail.com>,
        "Enrico Weigelt, metux IT consult" <info@metux.net>
Cc:     Pantelis Antoniou <pantelis.antoniou@konsulko.com>,
        Frank Rowand <frowand.list@gmail.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        devicetree <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
References: <CAGngYiVa9v9jGPNu4W+KHUnvemKU-BVE89-XNLcWOmoZjAPMTg@mail.gmail.com>
 <24f1687c-043a-a15e-0be4-8392e7b5c96b@metux.net>
 <CAGngYiVokqYkEiQTcqAMnvif3qEWkPOb1cAk+4rvwgxBKZ5Ukw@mail.gmail.com>
From:   "Enrico Weigelt, metux IT consult" <lkml@metux.net>
Message-ID: <1acc987a-d844-fca7-77eb-cf1d466f35c1@metux.net>
Date:   Wed, 12 Aug 2020 15:27:47 +0200
User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.10.0
MIME-Version: 1.0
In-Reply-To: <CAGngYiVokqYkEiQTcqAMnvif3qEWkPOb1cAk+4rvwgxBKZ5Ukw@mail.gmail.com>
Content-Type: text/plain; charset=utf-8
Content-Language: tl
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On 07.08.20 16:17, Sven Van Asbroeck wrote:

Hi,

> I believe you're asking: "how do I associate device tree nodes to
> devices on a dynamically discoverable bus such as USB or PCI" right ?
> 
> I believe that already exists. You can describe the _expected_ pci or
> usb topology in the
> devicetree. If a device gets detected in a spot on the bus described
> in the tree, that
> snippet will be automatically associated with this device.
> 
> How to for usb:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/usb/usb-device.txt?h=v5.8
> 
> How to for pci:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/pci/pci.txt?h=v5.8

Thanks, that looks good.

But I've still got another problem: how can I use DT along w/ ACPI ?

The scenario goes like this:

* machine boots and probes normally w/ ACPI
* device is detected via USB, PCI, DMI, etc -> driver gets active
* driver loads (or carries) a DT snippet
* devices on the bus are instantiated via this DT snippet

(driver could also be some udev vodoo)

Example a:

* generic usb i2c dongle w/ some i2c devices attached behind it
* config (or DT snippet) somewhere in the FS

Example b:

* x86 board driver (eg. apu2/3/4), probed via DMI
* just instantiates a bunch of generic drivers and wires up
  devices (gpio, leds, keys, ...)


Do you think we can already do that ?
Otherwise, what has to be done to achieve that ?	


--mtx

-- 
---
Hinweis: unverschlüsselte E-Mails können leicht abgehört und manipuliert
werden ! Für eine vertrauliche Kommunikation senden Sie bitte ihren
GPG/PGP-Schlüssel zu.
---
Enrico Weigelt, metux IT consult
Free software and Linux embedded engineering
info@metux.net -- +49-151-27565287