From: Arnd Bergmann <arnd@kernel.org>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: "Enrico Weigelt, metux IT consult" <lkml@metux.net>,
Viresh Kumar <viresh.kumar@linaro.org>,
Stefan Hajnoczi <stefanha@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
Viresh Kumar <vireshk@kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
virtualization@lists.linux-foundation.org,
Bartosz Golaszewski <bgolaszewski@baylibre.com>,
"Stefano Garzarella --cc virtualization @ lists .
linux-foundation . org" <sgarzare@redhat.com>,
"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
Stratos Mailing List <stratos-dev@op-lists.linaro.org>,
"Enrico Weigelt, metux IT consult" <info@metux.net>,
Jason Wang <jasowang@redhat.com>
Subject: Re: [Stratos-dev] [PATCH V3 1/3] gpio: Add virtio-gpio driver
Date: Thu, 10 Jun 2021 21:41:01 +0200 [thread overview]
Message-ID: <CAK8P3a1E7WzhX4NvUPn6iDzsUqTzAEMcsow7feTGRWTLe9+FFQ@mail.gmail.com> (raw)
In-Reply-To: <YMJF5fF31ksmSdiq@myrica>
On Thu, Jun 10, 2021 at 7:03 PM Jean-Philippe Brucker
<jean-philippe@linaro.org> wrote:
>
> On Thu, Jun 10, 2021 at 04:00:39PM +0000, Enrico Weigelt, metux IT consult via Stratos-dev wrote:
> > On 10.06.21 15:22, Arnd Bergmann wrote:
> >
> > > Can you give an example of how this would be hooked up to other drivers
> > > using those gpios. Can you give an example of how using the "gpio-keys" or
> > > "gpio-leds" drivers in combination with virtio-gpio looks like in the DT?
> >
> > Connecting between self-probing bus'es and DT is generally tricky. IMHO
> > we don't have any generic mechanism for that.
>
> DT does have a generic description of PCI endpoints, which virtio-iommu
> relies on to express the relation between IOMMU and endpoint nodes [1].
> I think the problem here is similar: the client node needs a phandle to
> the GPIO controller which may use virtio-pci transport?
Right, the code to set dev->of_node is fairly simple, the device probe
just needs to scan for child nodes. Aside from PCI, similar code exists
for USB and MMC/SDIO, which are usually discoverable but sometimes
need additional properties.
> Note that it mostly works if the device is on the root PCI bus. Behind a
> bridge the OS may change the device's bus number as needed, so the BDF
> reference in DT is only valid if the software providing the DT description
> (VMM or firmware) initializes bus numbers accordingly (and I don't
> remember if Linux supports this case well).
I think you can mark the host bridge as "probe-only" to prevent the OS
(at least Linux) from renumbering the buses.
The part I did not find though is assigning dev->of_node in the virtio_device
to a child of the PCI device node.
Arnd
next prev parent reply other threads:[~2021-06-10 19:43 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-10 12:09 [PATCH V3 0/3] gpio: Add virtio based driver Viresh Kumar
2021-06-10 12:16 ` [PATCH V3 1/3] gpio: Add virtio-gpio driver Viresh Kumar
2021-06-10 13:22 ` Arnd Bergmann
2021-06-10 16:00 ` Enrico Weigelt, metux IT consult
[not found] ` <01000179f6a7715c-cd106846-7770-4088-bb7c-a696bfcbf83e-000000@email.amazonses.com>
2021-06-10 17:03 ` [Stratos-dev] " Jean-Philippe Brucker
2021-06-10 19:41 ` Arnd Bergmann [this message]
2021-06-14 10:21 ` Viresh Kumar
2021-06-14 12:31 ` Arnd Bergmann
2021-06-14 12:49 ` Vincent Guittot
[not found] ` <0100017a0a9264cc-57668c56-fdbf-412a-9f82-9bf95f5c653e-000000@email.amazonses.com>
2021-06-14 12:58 ` [Stratos-dev] " Arnd Bergmann
2021-06-14 13:24 ` Vincent Guittot
2021-06-14 20:54 ` Arnd Bergmann
2021-06-15 7:30 ` Vincent Guittot
2021-06-10 15:54 ` Enrico Weigelt, metux IT consult
2021-06-10 16:57 ` Viresh Kumar
2021-06-10 20:46 ` Linus Walleij
2021-06-11 3:56 ` Viresh Kumar
2021-06-11 7:42 ` Geert Uytterhoeven
2021-06-11 8:01 ` Viresh Kumar
2021-06-11 8:22 ` Geert Uytterhoeven
2021-06-15 11:15 ` Viresh Kumar
2021-06-15 11:37 ` Geert Uytterhoeven
2021-06-15 20:03 ` Linus Walleij
2021-06-16 1:45 ` Viresh Kumar
2021-06-14 8:07 ` Enrico Weigelt, metux IT consult
2021-06-14 8:12 ` Andy Shevchenko
2021-06-14 9:14 ` Viresh Kumar
2021-06-14 9:17 ` Enrico Weigelt, metux IT consult
2021-06-14 9:52 ` Viresh Kumar
2021-06-14 9:12 ` Viresh Kumar
2021-06-14 9:29 ` Enrico Weigelt, metux IT consult
2021-06-14 8:03 ` Enrico Weigelt, metux IT consult
2021-06-14 9:24 ` Viresh Kumar
2021-06-16 3:30 ` Bjorn Andersson
2021-06-16 15:52 ` Enrico Weigelt, metux IT consult
2021-06-18 9:13 ` Linus Walleij
2021-06-21 17:25 ` Bjorn Andersson
2021-06-10 12:16 ` [PATCH V3 2/3] gpio: virtio: Add IRQ support Viresh Kumar
2021-06-10 21:30 ` Linus Walleij
2021-06-14 7:08 ` Viresh Kumar
2021-06-10 12:16 ` [PATCH V3 3/3] MAINTAINERS: Add entry for Virtio-gpio Viresh Kumar
[not found] ` <01000179f5da7763-2ea817c6-e176-423a-952e-de02443f71e2-000000@email.amazonses.com>
2021-06-10 17:40 ` [PATCH V3 1/3] gpio: Add virtio-gpio driver Jean-Philippe Brucker
2021-06-11 3:39 ` Viresh Kumar
[not found] ` <01000179f9276678-ae2bb25f-4c0c-4176-b906-650c585b9753-000000@email.amazonses.com>
2021-06-11 8:34 ` [Stratos-dev] " Arnd Bergmann
2021-06-14 5:26 ` Viresh Kumar
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