Re: [PATCH 1/3] MFD: introduce lpc_sch for Intel SCH LPC bridge

Denis Turischev
2010-02-17T10:02:38Z

Jean Delvare wrote:
> On Tue, 16 Feb 2010 11:57:46 -0800, David Brownell wrote:
>> On Thursday 11 February 2010, Denis Turischev wrote:
>>> Intel Poulsbo (SCH) chipset LPC bridge controller contains several
>>> functions. Creating and MFD driver for the LPC bridge controller allows
>> Spelling nit: "Creating an" (not and). Keyboard, brain, or edit fault. ;)
>>
>>
>>> simultaneous use of SMBus and GPIO interfaces on the SCH.
>> This looks like the right way to package such southbridge level
>> componentry. Maye not just these two interfaces, either.
>>
>> But ... how does this play with ACPI? The last several Intel
>> systems I looked at seemed to expect ACPI to manage GPIOs and the
>> IRQs they may issue. (He wrote, staring at an ICH8-system where
>> ACPI uses GPIOs to manage several buttons and LEDs.)
>>
>> It would seem error-prone to ignore that coupling on systems
>> with ACPI. Linux has enough trouble sorting out issues caused
>> by buggy AML (ACPI bytecode) without introducing conflicts in
>> who manages which hardware resource (ACPI vs. operating system).
>
> Might be a good idea to use acpi_check_resource_conflict() or similar
> before instantiating the platform devices.

May be it worth to add such resource check directly to mfd_add_device function?

>
>> Of course, if ACPI weren't being used to hide such board-specific
>> details from operating systems, such issues would not exist. But
>> such hiding is one of the basic goals of ACPI ... annoying.
>
> Don't start me on this :(
>