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

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Hi Sean,

I finally managed to open the device and it has an IT8225VG-128.
I can't find any datasheet for that device though.

Thanks
Michael

On Sun, Sep 27, 2020 at 12:03 AM Sean Young <sean@xxxxxxxx> wrote:
>
> On Sat, Sep 26, 2020 at 04:18:10PM +0200, Michael Zimmermann wrote:
> > On Sat, Sep 26, 2020 at 3:33 PM Sean Young <sean@xxxxxxxx> wrote:
> > >
> > > 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.
> >
> > Hi Sean,
> >
> > superiotool r4.12-2974-ga32df26ec07
> > Found Aspeed AST2400 (id=0x00) at 0x2e
> >
> > Which is kinda confusing. So either the superiotool detection is
> > flawed or the PN50 actually has an AST2400 and is programmed to
> > emulate the IR part of an IT8708F.
> > Also, that thing seems beefy enough to be the systems EC, does that seem likely?
>
> Strange. To be honest, I don't know.
>
> So looking at the driver, there are four models supported. They have an
> io_region_size of IT87_IOREG_LENGTH, IT8708_IOREG_LENGTH, and
> IT8709_IOREG_LENGTH. That's 8, 8, and 2. The header file also has a size
> of IT85_IOREG_LENGTH which is 16, but this is not used anywhere.
>
> The documentation I can find for one IT85 model is:
>
> http://www.recomb-omsk.ru/published/SC/html/scripts/doc/94689_datasheet_IT8512E_F_V0.4.1.pdf
>
> As far as I can make out, if it was this device, the driver wouldn't work
> at all.
>
> I'm thinking the likely explanation is that the DSDT is wrong and we should
> make the change as you originally suggested.
>
>
> Sean
>
>
> >
> > Thanks
> > Michael
> > >
> > > >
> > > > Thanks
> > > > Michael
> > > >
> > > > On Sat, Sep 26, 2020 at 1:30 PM Sean Young <sean@xxxxxxxx> 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



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