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

Jean Delvare
2010-02-16T21:49:54Z

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.

> 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 :(

--
Jean Delvare