From: Horatiu Vultur <horatiu.vultur@microchip.com>
To: Michael Walle <michael@walle.cc>
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>,
Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
devicetree <devicetree@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: fwnode_for_each_child_node() and OF backend discrepancy
Date: Thu, 30 Jun 2022 22:16:17 +0200 [thread overview]
Message-ID: <20220630201617.sqpihcevym7sxqng@soft-dev3-1.localhost> (raw)
In-Reply-To: <4782de1fc6692a98bd6c267c2714325f@walle.cc>
The 06/28/2022 23:07, Michael Walle wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>
> Am 2022-06-28 22:52, schrieb Horatiu Vultur:
> > The 06/28/2022 22:28, Andy Shevchenko wrote:
> > > EXTERNAL EMAIL: Do not click links or open attachments unless you know
> > > the content is safe
> > >
> > > On Tue, Jun 28, 2022 at 5:17 PM Krzysztof Kozlowski
> > > <krzysztof.kozlowski@linaro.org> wrote:
> > > > On 28/06/2022 17:09, Michael Walle wrote:
> >
> > Hi,
> >
> > Sorry for joint this late.
> >
> > >
> > > ...
> > >
> > > > > Mh. Assume a SoC with an integrated ethernet switch. Some ports
> > > > > are externally connected, some don't. I'd think they should be disabled,
> > > > > no? Until now, all bindings I know, treat them as disabled. But OTOH
> > > > > you still need to do some configurations on them, like disable port
> > > > > forwarding, disable them or whatever. So the hardware is present, but
> > > > > it is not connected to anything.
> > > >
> > > > I see your point and the meaning is okay... except that drivers don't
> > > > touch disabled nodes. If a device (with some address space) is disabled,
> > > > you do not write there "please be power off". Here the case is a bit
> > > > different, because I think ports do not have their own address space.
> > > > Yet it contradicts the logic - something is disabled in DT and you
> > > > expect to perform actual operations on it.
> > >
> > > You beat me up to this comment, I also see a contradiction of what
> > > "disabled" means in your, Michael, case and what it should be.
> > >
> > > If you need to perform an operation on some piece of HW, it has not to
> > > be disabled.
> > >
> > > Or, you may deduce them by knowing how many ports in hardware (this is
> > > usually done not by counting the nodes, but by a property) and do
> > > whatever you want on ones, you have not listed (by port_num) in the
> > > array of parsed children.
> >
> > It is not possible to have a defined for the MAX number of ports that
> > supported by lan966x. Which is 8. And assigned that define to
> > num_phys_ports instead of counting the entries in DT?
>
> You mean also for the lan9662? I'm pretty sure that doesn't
> work. Have a look where num_phys_ports is used. One random
> example:
> https://elixir.bootlin.com/linux/latest/source/drivers/net/ethernet/microchip/lan966x/lan966x_main.c#L874
>
> So if your switch only has 4 ports, then I'd guess you'll
> access a non-existing register.
Underneath lan662 and lan668 is the same chip. The HW people disable
some ports/features on each platform but from what I know you will still
be able to access the registers.
>
> -michael
--
/Horatiu
next prev parent reply other threads:[~2022-06-30 20:12 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-27 12:49 fwnode_for_each_child_node() and OF backend discrepancy Michael Walle
2022-06-27 13:08 ` Krzysztof Kozlowski
2022-06-27 13:33 ` Rafael J. Wysocki
2022-06-28 10:32 ` Krzysztof Kozlowski
2022-06-28 14:41 ` Sakari Ailus
2022-06-29 10:50 ` Rafael J. Wysocki
2022-06-29 13:01 ` Grant Likely
2022-06-28 11:10 ` Andy Shevchenko
2022-06-28 11:36 ` Michael Walle
2022-06-28 13:11 ` Andy Shevchenko
2022-06-28 13:23 ` Michael Walle
2022-06-28 13:29 ` Andy Shevchenko
2022-06-28 13:47 ` Michael Walle
2022-06-28 13:51 ` Krzysztof Kozlowski
2022-06-28 14:22 ` Michael Walle
2022-06-28 14:36 ` Krzysztof Kozlowski
2022-06-28 15:09 ` Michael Walle
2022-06-28 15:17 ` Krzysztof Kozlowski
2022-06-28 20:28 ` Andy Shevchenko
2022-06-28 20:52 ` Horatiu Vultur
2022-06-28 21:07 ` Michael Walle
2022-06-30 20:16 ` Horatiu Vultur [this message]
2022-06-30 21:00 ` Michael Walle
2022-06-30 21:21 ` Vladimir Oltean
2022-06-30 21:32 ` Michael Walle
2022-06-28 21:59 ` Vladimir Oltean
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220630201617.sqpihcevym7sxqng@soft-dev3-1.localhost \
--to=horatiu.vultur@microchip.com \
--cc=andriy.shevchenko@linux.intel.com \
--cc=andy.shevchenko@gmail.com \
--cc=devicetree@vger.kernel.org \
--cc=krzysztof.kozlowski+dt@linaro.org \
--cc=krzysztof.kozlowski@linaro.org \
--cc=linux-acpi@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=michael@walle.cc \
--cc=rafael@kernel.org \
--cc=robh+dt@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).