Re: Fwd: [alsa-devel] [PATCH 1/1] SPI : spi-pxa2xx : fix spi init of WM510205 codec via ACPI (resend)

[Charles Keepax <ckeepax-yzvPICuk2AATkU/dhu1WVueM+bqZidxxQQ4Iyu8u01E@public.gmane.org>]

On Thu, Jun 25, 2015 at 04:56:12PM +0100, Mark Brown wrote:
> On Thu, Jun 25, 2015 at 04:44:07PM +0100, Charles Keepax wrote:
> > On Thu, Jun 25, 2015 at 03:58:53PM +0100, Mark Brown wrote:
> > > On Thu, Jun 25, 2015 at 02:18:23PM +0200, Christian Hartmann wrote:
> 
> > > >                 Name (_HID, "WM510205")  // _HID: Hardware ID
> > > >                 Name (_CID, "WM510205")  // _CID: Compatible ID
> > > >                 Name (_DDN, "Wolfson Microelectronics Audio WM5102")
> 
> > > Separately to the chip select discussion one thing to highlight here is
> > > that for some reason the BIOS is listing the device as "WM510205" rather
> > > than "WM5102" - do those extra numbers mean anything and does this mean
> > > that WM50120[1-4] and possibly higher numbers are also valid?
> 
> > From my brief discussions with the Windows guys here on this
> > basically those last two digits are being used to inform the
> > Windows driver of use-case setup. So here it will set things up
> > for whatever the Window's driver considers to be setup "5".
> 
> Yay for scalability and abstraction.

Well it certainly is abstract.

> 
> > I think from the Linux side we can safely ignore those last two
> > digits. I expect that all systems of the same make and model
> > would report the same last two digits but that it might change
> > between models if the Windows driver is expected to something
> > differently for that model.
> 
> Well, we might want to consider using this to set our platform data
> instead of the machine ID if people have just been copying a smallish
> set of reference designs, it might might make for a slightly smaller set
> of ID tables than the machine ID based stuff does.
> 
> Due to the way ACPI ID matching works we'll also need to add every
> suffix individually to the table, we're looking for complete matches not
> substring matches here.

>From what I can gather currently yes every system has a different
suffix so it should be fine to skip checking the machine ID and
just use the ACPI ID to select the pdata.

Thanks,
Charles
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