linux-kernel - Re: [PATCH] ACPI / GPIO: Driver GPIO mappings for ACPI GPIOs

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Message-ID: <1433051.htaUTMPMBY@vostro.rjw.lan>
Date:	Mon, 03 Nov 2014 23:56:53 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Arnd Bergmann <arnd@...db.de>,
	Alexandre Courbot <gnurou@...il.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Grant Likely <grant.likely@...aro.org>,
	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	Aaron Lu <aaron.lu@...el.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Bryan Wu <cooloney@...il.com>,
	Darren Hart <dvhart@...ux.intel.com>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH] ACPI / GPIO: Driver GPIO mappings for ACPI GPIOs

On Monday, November 03, 2014 02:22:10 PM Linus Walleij wrote:
> On Sat, Oct 25, 2014 at 12:05 AM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> 
> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >
> > Provide a way for device drivers using GPIOs described by ACPI
> > GpioIo resources in _CRS to tell the GPIO subsystem what names
> > (connection IDs) to associate with specific GPIO pins defined
> > in there.
> >
> > To do that, a driver needs to define a mapping table as a
> > NULL-terminated array of struct acpi_gpio_mapping objects
> > that each contain a name, a pointer to an array of pin data
> > (struct acpi_gpio_params) objects and the size of that array.
> >
> > Each struct acpi_gpio_params object consists of three fields,
> > crs_entry_index, pin_index, active_low, representing the index of
> 
> I prefer that you call the second thing "line_index" rather than
> "pin_index". Not all GPIOs in the world are tied to physical pins.
> Also it is easy to confuse stuff with the pin control terminology
> if it's called "pin".
> 
> > the target GpioIo()/GpioInt() resource in _CRS starting from zero,
> > the index of the target pin in that resource starting from zero,
> > and the active-low flag for that pin, respectively.
> >
> > Next, the mapping table needs to be passed as the second argument to
> > acpi_dev_add_driver_gpios() that will register it with the ACPI device
> > object pointed to by its first argument.  That object must represent
> > the ACPI namespace node containing the _CRS object referred to by the
> > GPIO mapping.  That should be done in the driver's .probe() routine.
> >
> > On removal, the driver should unregister its GPIO mapping table
> > by calling acpi_dev_remove_driver_gpios() on the ACPI device
> > object where that table was previously registered.
> >
> > Included are fixes from Mika Westerberg.
> >
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> And "pin" is mentioned several times in the commit message.
> I prefer that we talk about "lines".
> 
> (...)
> 
> > +struct acpi_gpio_params {
> > +       unsigned int crs_entry_index;
> > +       unsigned int pin_index;
> 
> So line_index;
> 
> > +       bool active_low;
> > +};
> 
> With that change:
> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>

OK, made the changes and added your Reviewed-by.

One semi-related question though.  Alexandre ACKed the patch before, so
what did that mean from the GPIO subsystem's perspective?  Was the patch
approved, not approved, semi-approved?

Rafael

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