Re: ITE8708 on ASUS PN50 uses a 16 byte io region

[Sean Young <sean@mess.org>]

Hi Michael,

On Sat, Sep 26, 2020 at 02:32:21PM +0200, Michael Zimmermann wrote:
> The acpi _HID name of the device is "ITE8708" and the device works
> with linux's ITE8708 config.
> 
> I can't find any datasheet or even product page for that IC so I don't
> know what footprint to look for when looking at the PCB - none of the
> bigger ICs near the IR sensor have that name on them and the smaller
> ones usually don't have any useful information printed on them.
> Additionally I can only access one side of the PCB because I couldn't
> figure out how to fully disassemble the device yet.

This is a super i/o device, so this handles stuff like serial ports,
parallel ports, floppy disks. All the legacy stuff you don't need any more.

There is a coreboot tool which can identify super i/o devices:

	https://www.coreboot.org/Superiotool

The super io devices I've seen are about 2cm by 3cm.

I could find a datasheet for the IT8712F on google.


Sean

PS. Please don't top post.

> 
> Thanks
> Michael
> 
> On Sat, Sep 26, 2020 at 1:30 PM Sean Young <sean@mess.org> wrote:
> >
> > On Sat, Sep 26, 2020 at 10:22:46AM +0200, Michael Zimmermann wrote:
> > > Hi,
> > >
> > > here's the resource descriptor from my DSDT:
> > > Name (BUF0, ResourceTemplate ()
> > > {
> > >     IO (Decode16,
> > >         0x0000,             // Range Minimum
> > >         0x0000,             // Range Maximum
> > >         0x01,               // Alignment
> > >         0x10,               // Length
> > >         _Y1A)
> > >     IRQNoFlags (_Y1B)
> > >         {}
> > >     DMA (Compatibility, NotBusMaster, Transfer8, )
> > >         {}
> > > })
> > >
> > > As you can see it uses 16 bytes for the IO region while the driver
> > > drivers/media/rc/ite-cir.c expects 8.
> > > I don't see any obvious reason why they do that since they only seem
> > > to write two words in there, and if I edit the DSDT to change the
> > > length from 0x10 to 0x8 the linux driver detects the device properly
> > > it works just fine.
> > >
> > > So is this a bug on ASUS' side or should we just accept longer regions
> > > for the same device type?
> >
> > So looking at the driver, some devices do have an io region of 16 and
> > others expect 8. See the io_region_size field of ite_dev_descs.
> >
> > So for ITE8708 the io_region_size is set to 8. Does your device really
> > have an ITE8708 or is the DSDT wrong?
> >
> >
> > Sean