Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_SPI driver to 2.6.35

["Masayuki Ohtake" <masa-korg@dsn.okisemi.com>]

----- Original Message ----- 
From: "Grant Likely" <grant.likely@secretlab.ca>
To: "Masayuki Ohtake" <masa-korg@dsn.okisemi.com>
Cc: "Thomas Gleixner" <tglx@linutronix.de>; <meego-dev@meego.com>; "LKML" <linux-kernel@vger.kernel.org>; "David
Brownell" <dbrownell@users.sourceforge.net>; <qi.wang@intel.com>; <yong.y.wang@intel.com>;
<andrew.chih.howe.khor@intel.com>; <arjan@linux.intel.com>; <gregkh@suse.de>; "Tomoya MORINAGA"
<morinaga526@dsn.okisemi.com>; "David Woodhouse" <dwmw2@infradead.org>; "Alan Cox" <alan@lxorguk.ukuu.org.uk>
Sent: Tuesday, August 31, 2010 3:03 PM
Subject: Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_SPI driver to 2.6.35


> On Mon, Aug 30, 2010 at 7:45 PM, Masayuki Ohtake
> <masa-korg@dsn.okisemi.com> wrote:
> > ----- Original Message -----
> >> From: "Grant Likely" <grant.likely@secretlab.ca>
> >> To: "Masayuki Ohtake" <masa-korg@dsn.okisemi.com>
> >> Cc: "Thomas Gleixner" <tglx@linutronix.de>; <meego-dev@meego.com>; "LKML" <linux-kernel@vger.kernel.org>; "David
> > Brownell" <dbrownell@users.sourceforge.net>; <qi.wang@intel.com>; <yong.y.wang@intel.com>;
> > <andrew.chih.howe.khor@intel.com>; <arjan@linux.intel.com>; <gregkh@suse.de>; "Tomoya MORINAGA"
> > <morinaga526@dsn.okisemi.com>; "David Woodhouse" <dwmw2@infradead.org>; "Alan Cox" <alan@lxorguk.ukuu.org.uk>
> >> Sent: Tuesday, August 31, 2010 3:23 AM
> >> Subject: Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_SPI driver to 2.6.35
> >>
> >>
> >> On Mon, Aug 30, 2010 at 1:28 AM, Masayuki Ohtake
> >> <masa-korg@dsn.okisemi.com> wrote:
> >> > ----- Original Message -----
> >> > From: "Grant Likely" <grant.likely@secretlab.ca>
> >> > To: "Thomas Gleixner" <tglx@linutronix.de>
> >> > Cc: "Masayuki Ohtak" <masa-korg@dsn.okisemi.com>; <meego-dev@meego.com>; "LKML" <linux-kernel@vger.kernel.org>;
> > "David
> >> > Brownell" <dbrownell@users.sourceforge.net>; <qi.wang@intel.com>; <yong.y.wang@intel.com>;
> >> > <andrew.chih.howe.khor@intel.com>; <arjan@linux.intel.com>; <gregkh@suse.de>; "Tomoya MORINAGA"
> >> > <morinaga526@dsn.okisemi.com>; "David Woodhouse" <dwmw2@infradead.org>; "Alan Cox" <alan@lxorguk.ukuu.org.uk>
> >> > Sent: Saturday, August 28, 2010 4:20 AM
> >> > Subject: Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_SPI driver to 2.6.35
> >> >
> >> >
> >> >> On Fri, Aug 27, 2010 at 12:53 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
> >> >> > B1;2401;0cOn Fri, 27 Aug 2010, Grant Likely wrote:
> >> >> >> [cc'ing Thomas Gleixner and David Woodhouse since this driver needs to
> >> >> >> get some data about the platform (to know what spi_devices are
> >> >> >> present) and I don't know how that is handled for x86 SoCs.]
> >> >> >
> >> >> > The best way to do all this platform specific configuration is to use
> >> >> > device tree. I really don't want to have x86/mach-xyz/board[A-Z]
> >> >> > horror, which is unavoidable when we don't get a sensible way to
> >> >> > configure the boards.
> >> >>
> >> >> I knew you were going to say that! :-)
> >> >>
> >> >> Ohtak-san, for this patch I'd like you to drop the separate driver
> >> >> that only registers the spi_devices and just submit the core driver.
> >> >
> >> > Sorry, I can't follow your discussion by lack of SPI knowledge.
> >> > Which the above mean that "spi_register_board_info" moves to our spi_pch or
> >> > delete for our driver ?
> >>
> >> I mean remove drivers/spi/spi_pch_device.c and the related Kconfig
> >> bits from this patch.
> >> The spi_device registration is a separate task
> >> which should be submitted in a separate patch, and would be better
> >> handled in either platform support code or with a device tree.
> >
> > How should we register spi_device information ?
> > Could you show reference driver ?
>
> Well, to start with, the registration code currently in
> spi_pch_device.c is probably pretty much unusable for any platform
> other than the development board that you're working on.  Every
> machine using the topcliff chip will have a different set of spi
> devices attached to the bus.  So, you'll need a method for having a
> different set of registrations depending on the machine.
>
> Traditionally with ARM systems, there is a separate .c file for each
> machine (see arch/arm/mach-*/*.c) which registers the expected
> devices.  In PowerPC the spi devices are described in a device tree
> file (arch/powerpc/boot/dts/*) which the kernel will parse and
> register the devices it finds.  x86 doesn't support either approach
> because traditionally the kernel is either able to detect the
> hardware, or it can get information from the BIOS (which doesn't work
> for embedded x86).
>
> The x86 maintainers want to adopt the device tree approach for
> describing devices.  Using device tree data in an spi bus driver is
> easy.  All that is required is to supply the of_node pointer to the
> spi bus before registering it.  Search for 'of_node' in
> drivers/spi/mpc52xx_spi.c for an example.  However, device tree
> support is not yet available for x86, so there is still some
> development that needs to be done.
>
> Regardless, the topcliff spi driver can still be merged into mainline
> without the spi_device registration code, and you can keep your
> personal copy of spi_pch_device.c for testing while the details about
> device tree support for x86 get worked out.
>
> g.
>
Hi Grant,

Thank you very much.
I could understand well.

Can I post our SPI patch for Topcliff without 'of_node' code and spi_device registration code?

Thanks, Ohtake(OKISemi)