[Ksummit-2013-discuss] [ATTEND] ACPI vs DT

[Simon Guinot]

On Tue, Jul 30, 2013 at 01:19:13AM -0700, Guenter Roeck wrote:
> On 07/27/2013 03:33 AM, Simon Guinot wrote:
> >On Sat, Jul 27, 2013 at 01:49:27AM -0500, linux at roeck-us.net wrote:
> >>Quoting "Rafael J. Wysocki" <rjw at sisk.pl>:
> >>
> >>>On Thursday, July 25, 2013 10:16:28 AM Linus Walleij wrote:
> >>>>On Thu, Jul 25, 2013 at 1:05 AM, Rafael J. Wysocki <rjw at sisk.pl> wrote:
> >>>>
> >>>>>If you want a platform device to be created automatically for
> >>>>an object with
> >>>>>a particular PNP ID, add that PNP ID to acpi_platform_device_ids[] in
> >>>>>drivers/acpi/acpi_platform.c.  Then, you'll be able to match
> >>>>your driver to
> >>>>>that platform device using acpi_match_table, as described in
> >>>>>Documentation/acpi/enumeration.txt.
> >>>>>
> >>>>>Of course, that's going to work only if the ACPI namespace
> >>>>contains an object
> >>>>>with that PNP ID.  Now, you can ask me "What to do if it
> >>>>doesn't?" and that's
> >>>>>a good question.
> >>>>
> >>>>Hm this fits well into the topic of the thread.
> >>>>
> >>>>Atleast it seems like ACPI+ioport detection should be possible to
> >>>>combine in the same driver, so that if no PNP ID is found through
> >>>>ACPI, it can fall back to the ioport probing.
> >>>
> >>>Yes, that's viable in my opinion.
> >>>
> >>Sounds reasonable. I'll play with that and see if I can get it
> >>working on any of the boards I have access to.
> >
> >At least on my boards, I am almost sure that the ACPI namespace doesn't
> >contain any ID related with the super-I/O. At the time this boards has
> >been developed, LaCie (the board vendor) didn't do anything to add a
> >such ID.
> >
> That is one of my concerns. Another is that - at least to my knowledge
> - ACPI bindings may not be as well defined as, for example, PCI IDs or
> devicetree properties. Or maybe they are, and I just don't know
> where to find the necessary information.
> 
> >However, I will spend some time the next week to double-check that. And
> >I will also try to make coexist ACPI and ioport detection inside the
> >gpio-f7188x driver.
> >
> Another concern is that your driver is not synchronized with the
> hwmon driver and the watchdog driver for the same chip. The hwmon
> driver only uses superio access during initialization, so it is
> probably not that critical. The watchdog driver, however, uses
> superio accesses for its keepalive function. As far as I can see,
> you did not implement any synchronization (eg by using
> request_muxed_region before enabling superio accesses), which may
> result in the two drivers stepping on each other's foot.

I will fix that in the next driver version. Thanks for the catch.

Simon
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