linux-kernel - Re: [PATCH 1/8] gpio: Add Elba SoC gpio driver for spi cs control

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Date:   Sun, 22 Aug 2021 18:13:50 -0700
From:   Brad Larson <brad@...sando.io>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
        Arnd Bergmann <arnd@...db.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Mark Brown <broonie@...nel.org>,
        Serge Semin <fancer.lancer@...il.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Olof Johansson <olof@...om.net>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-spi <linux-spi@...r.kernel.org>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/8] gpio: Add Elba SoC gpio driver for spi cs control

Hi Andy,

On Mon, Mar 29, 2021 at 3:40 AM Andy Shevchenko
<andy.shevchenko@...il.com> wrote:
>
> On Mon, Mar 29, 2021 at 4:19 AM Brad Larson <brad@...sando.io> wrote:
> > On Sun, Mar 7, 2021 at 11:21 AM Andy Shevchenko
> > <andy.shevchenko@...il.com> wrote:
> > > On Thu, Mar 4, 2021 at 4:40 PM Brad Larson <brad@...sando.io> wrote:
>
> ...
>
> > > > +config GPIO_ELBA_SPICS
> > > > +       bool "Pensando Elba SPI chip-select"
> > >
> > > Can't it be a module? Why?
> >
> > All Elba SoC based platforms require this driver to be built-in to boot and
> > removing the module would result in a variety of exceptions/errors.
>
> Needs to be at least in the commit message.
>
>
>
> > > > +       depends on ARCH_PENSANDO_ELBA_SOC
> > > > +       help
> > > > +         Say yes here to support the Pensndo Elba SoC SPI chip-select driver
> > >
> > > Please give more explanation what it is and why users might need it,
> > > and also tell users how the module will be named (if there is no
> > > strong argument why it can't be a  module).
> > >
> > Fixed the typo.
>
> Yeah, according to the above, you better elaborate what this module is
> and why people would need it.
> Also can be a good hint to add
> default ARCH_MY_COOL_PLATFORM

Regarding the above module question and Kconfig definition, since I
first looked at this and reviewed the comments I realized I should be
using builtin.  The file gpio/Kconfig is currently this

config GPIO_ELBA_SPICS
        def_bool y
        depends on ARCH_PENSANDO_ELBA_SOC || COMPILE_TEST

> ...
>
> > > > +#include <linux/of.h>
> > >
> > > It's not used here, but you missed mod_devicetable.h.
> >
> > Removed <linux/of.h>.  There is no dependency on mod_devicetable.h.
>
> What do you mean? You don't use data structures from that?
> of_device_id or other ID structures are defined there. Your module
> works without them?
>
I typed the wrong filename.  I do still have <linux/of.h>

> > > > +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > > > +       p->base = devm_ioremap_resource(&pdev->dev, res);
> > >
> > > p->base = devm_platform_ioremap_resource(pdev, 0);
> >
> > Implementation follows devm_ioremap_resource() example in lib/devres.c.
>
> So? How does this make it impossible to address my comment?

I was simply stating that I followed the recommended API per the
source code although I don't recall if I was looking at 4.14, 5.10 or
linux-next at the time.  Changed to using
devm_platform_ioremap_resource().

> > > > +       if (IS_ERR(p->base)) {
> > >
> > > > +               dev_err(&pdev->dev, "failed to remap I/O memory\n");
> > >
> > > Duplicate noisy message.
> > >
> > > > +               return PTR_ERR(p->base);
> > > > +       }

Yep, I've removed the extraneous log message.

Regards,
Brad