Re: [PATCH 1/2] i2c: usbio: Add ACPI device-id for MTL-CVF devices

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Hans,

On Thu, Oct 02, 2025 at 10:56:47AM +0200, Hans de Goede wrote:
> Hi,
> 
> First of all I messed up the git format-patch command,
> there is no second patch in this series.
> 
> (at least not for the i2c subsystem. There is a similar GPIO
> patch but I send that out separately)
> 
> On 1-Oct-25 11:58 PM, Sakari Ailus wrote:
> > Hi Hans,
> > 
> > On Wed, Oct 01, 2025 at 11:23:10PM +0200, Hans de Goede wrote:
> >> Add "INTC10D2" ACPI device-id for MTL-CVF devices, like the Dell Latitude
> >> 7450.
> >>
> >> Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2368506
> >> Signed-off-by: Hans de Goede <hansg@kernel.org>
> >> ---
> >> Note this applies on top of the addition of the new i2c-usbio driver which
> >> is being merged through gregkh/usb.git usb-next
> >> ---
> >>  drivers/i2c/busses/i2c-usbio.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/drivers/i2c/busses/i2c-usbio.c b/drivers/i2c/busses/i2c-usbio.c
> >> index d42f9ab6e9a5..e7799abf6787 100644
> >> --- a/drivers/i2c/busses/i2c-usbio.c
> >> +++ b/drivers/i2c/busses/i2c-usbio.c
> >> @@ -27,6 +27,7 @@ static const struct acpi_device_id usbio_i2c_acpi_hids[] = {
> >>  	{ "INTC1008" }, /* MTL */
> >>  	{ "INTC10B3" }, /* ARL */
> >>  	{ "INTC10B6" }, /* LNL */
> >> +	{ "INTC10D2" }, /* MTL-CVF */
> > 
> > INTC10D2 is apparently already claimed by the LJCA I²C driver. Do you have
> > an actual system that uses USBIO and this HID?
> 
> Yes, see the Closes: tag which points to a bug-report which such a system:
> 
> https://bugzilla.redhat.com/show_bug.cgi?id=2368506
> 
> Let me also reply to your other comment here:
> 
> >> INTC10D2 is apparently already claimed by the LJCA I²C driver. Do you have
> >> an actual system that uses USBIO and this HID?
> > 
> > Actually it looks like i2c-ljca.c shouldn't list this HID. The same
> > probably goes for all 10CF--10D3.
> 
> I would not be so sure of this, there are at least some Dell systems
> which use a combination of ljca and Meteor Lake and I believe these
> do use the "INTC10D2" HID with LJCA for the I2C part and the same
> goes for the GPIO / SPI parts.. One example of such a system is
> the Dell Precision 5490.

LJCA on MTL is supposed to be 1008. Do you have the *SDT so we could verify
this?

> 
> The way these Intel uses these HIDs is really weird they seem to
> simply mean "I2C" on *a* USBIO expander with this generation CPU.

I can assure you I have nothing to do with this ACPI ID usage scheme. :-)

> 
> Where there really seems no reason to change the HID for CPU
> generations, where as it would be a good reason to change the HID
> if the actual USBIO expander is different ...

That's indeed supposed to be the case. Also the _HID should always reflect
the actual device and only _CID should indicate it's compatible with
something else. But that BIOS is already out there so there's little that
can be done to it anyway. :-\

-- 
Regards,

Sakari Ailus