linux-kernel - Re: [PATCH 2/2] i2c: smbus: Use device_ functions instead of of

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Date:   Thu, 16 Dec 2021 22:18:54 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Akhil R <akhilrajeev@...dia.com>
Cc:     Wolfram Sang <wsa@...nel.org>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian Koenig <christian.koenig@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Dmitry Osipenko <digetx@...il.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-tegra <linux-tegra@...r.kernel.org>,
        Krishna Yarlagadda <kyarlagadda@...dia.com>,
        Suresh Mangipudi <smangipudi@...dia.com>
Subject: Re: [PATCH 2/2] i2c: smbus: Use device_ functions instead of of_

On Thu, Dec 16, 2021 at 6:08 PM Akhil R <akhilrajeev@...dia.com> wrote:
> > On Thu, Dec 16, 2021 at 3:14 PM Akhil R <akhilrajeev@...dia.com> wrote:

...

> > > -       irq = of_property_match_string(adapter->dev.of_node, "interrupt-
> > names",
> > > -                                      "smbus_alert");
> > > +       irq = device_property_match_string(adapter->dev.parent, "interrupt-
> > names",
> > > +                                          "smbus_alert");
> >
> > Hmm... Adapter device node is not the same as the node for its parent.
> > Do you have some code that propagates of_node from parent to child?
> Adapter device does not have an of_node unless the adapter driver
> sets it, I guess. I see all the adapter drivers add the of_node and
> parent for adapter. Also, there are many places in i2c-core-base and
> i2c-core-acpi where adapter->dev.parent is referred to as the adapter
> driver device.
>
> Basically, adapter->dev.parent and adapter->dev.of_node would
> ultimately refer to the same device (or the of_node of that device),
> as far as I understand.
> >
> > I.o.w. I would expect to see
> >
> >        irq = device_property_match_string(&adapter->dev, "interrupt-names",
> >
> > here.
> It would then require adding the fw_node as well from the adapter driver.
> I felt it made more sense to refer adapter->dev.parent here as most of the
> (or rather all of the) adapter drivers already sets it.

Is this
https://elixir.bootlin.com/linux/latest/source/drivers/i2c/i2c-core-base.c#L1047
what you are looking for?

...

> > >         if (irq == -EINVAL || irq == -ENODATA)
> > >                 return 0;
> > >         else if (irq < 0)
> >
> > TBH the entire code smells. "Interesting" way of getting an optional named
> > interrupt.
> I felt it useful to have it this way as it would remain agnostic to device tree and
> the ACPI. We would not have to add redundant codes in adapter drivers that
> are using ACPI table.
>
> Named interrupts for the ACPI as well, I feel would be a useful addition that can
> prove to be of value more than this change; I believe.

Me too. My comment was about current state of affairs, and not to your change.

-- 
With Best Regards,
Andy Shevchenko