Re: [REGRESSION][BISECTED] Lenovo IdeaPad touchpad does not work when idma64 is present in initramfs

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Thu, Jan 22, 2026 at 05:29:38PM -0500, correctmost wrote:
> On Thu, Jan 22, 2026, at 6:00 AM, Mika Westerberg wrote:
> > On Wed, Jan 21, 2026 at 05:19:17PM +0200, Andy Shevchenko wrote:
> >> > Well I mean if touchpads actually worked prior this idma64 commit and now
> >> > they don't isn't that a regression?
> >> 
> >> I don't think so, because commit did the right thing and just revealed an issue
> >> that was rather hidden. Reverting is not an option.
> >
> > I now looked at both working and non-working /proc/interrupts and when it
> > is working there is no interrupt flood at all:
> >
> >  27:          0          0          0          0       2277          0  
> >         0          0          0          0          0          0 
> > IR-IO-APIC   27-fasteoi   idma64.0, i2c_designware.0
> >
> > This makes me think that perhaps the toucpad is powered off and that causes
> > the issue until I2C HID probes and resets it. I looked at the ACPI tables
> > but I did not (yet) find anything that stands out.
> >
> > I wonder if it was tried to put i2c-designware*.ko and i2c-hid.ko into the
> > initramfs, and does work it around? I would expect so.
> 
> I don't see an i2c-designware module loaded when my touchpad works:

It's most likely built-in. This is the requirement when kernel wants to support
some of the (old) Intel hardware. If you see it in `cat /proc/interrupts`, or
in the output of `lspci -nk`, it's there.

> $ grep -i i2c /proc/modules 
> i2c_i801 40960 0 - Live 0x0000000000000000
> i2c_smbus 20480 1 i2c_i801, Live 0x0000000000000000
> i2c_mux 16384 1 i2c_i801, Live 0x0000000000000000
> i2c_hid_acpi 12288 0 - Live 0x0000000000000000
> i2c_hid 45056 1 i2c_hid_acpi, Live 0x0000000000000000
> i2c_algo_bit 24576 2 xe,i915, Live 0x0000000000000000
> 
> I tried adding all of the following modules to my initramfs image and I still
> encountered the touchpad failure:
> 
> drivers/dma/idma64.ko.zst
> drivers/hid/i2c-hid/i2c-hid-acpi.ko.zst
> drivers/hid/i2c-hid/i2c-hid.ko.zst
> drivers/i2c/i2c-mux.ko.zst
> drivers/i2c/i2c-smbus.ko.zst
> drivers/i2c/busses/i2c-i801.ko.zst
> drivers/mfd/intel-lpss.ko.zst
> drivers/mfd/intel-lpss-pci.ko.zst
> 
> (The drivers/i2c/algos/i2c-algo-bit.ko.zst module was already present in
> the working image, so I didn't have to add it.)

-- 
With Best Regards,
Andy Shevchenko