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

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

On Wed, Feb 04, 2026 at 08:11:27AM -0500, correctmost wrote:
> On Wed, Feb 4, 2026, at 7:31 AM, Mika Westerberg wrote:
> > On Tue, Feb 03, 2026 at 07:39:36AM -0500, correctmost wrote:
> >> On Tue, Feb 3, 2026, at 5:04 AM, Mika Westerberg wrote:
> >> > On Mon, Feb 02, 2026 at 06:16:02AM -0500, correctmost wrote:
> >> >> > Could you drop the above hack again so that it should "fail". Then build
> >> >> > the kernel with CONFIG_PREEMPT_VOLUNTARY=y and add the below hack. Perhaps
> >> >> > this is just lucky timing? Please try a couple of boots and make sure the
> >> >> > results are the same each time.
> >> >> 
> >> >> I cold booted five times and the touchpad did not work during any of those boots.
> >> >
> >> > Thanks!
> >> >
> >> >> I noticed that the "probe with driver" failure reports -22 instead of -110 now:
> >> >> 
> >> >> [   33.023932] i2c_hid_acpi i2c-ELAN06FA:00: Report Descriptor: 05 01 09 02 a1 01 85 01 09 01 a1 00 05 09 19 01 29 02 15 00 25 01 75 01 95 02 81 02 95 06 81 03 05 01 09 30 09 31 15 81 25 7f 75 08 95 02 81 06 75 08 95 05 81 03 c0 06 00 ff 09 01 85 0e 09 c5
> >> >> [   33.026070] hid-generic 0018:04F3:327E.0001: item fetching failed at offset 638/675
> >> >> [   33.027573] hid-generic 0018:04F3:327E.0001: probe with driver hid-generic failed with error -22
> >> >> ...
> >> >> [   33.183959] hid-multitouch 0018:04F3:327E.0001: item fetching failed at offset 638/675
> >> >> [   33.183975] hid-multitouch 0018:04F3:327E.0001: probe with driver hid-multitouch failed with error -22
> >> >> 
> >> >
> >> > This is really odd because "item fetching" is not really accessing any
> >> > hardware bus - it just parses the descriptor and the descriptor looks fine
> >> > to me (and this is the same as in case of working run):
> >> >
> >> > Usage Page (Generic Desktop)
> >> > Usage (Generic Desktop.Mouse)
> >> > Collection (1)
> >> >   Report ID (1)
> >> >   Usage (Generic Desktop.Pointer)
> >> >   Collection (0)
> >> >     Usage Page (Button)
> >> >     Usage Minimum (1)
> >> >     Usage Maximum (2)
> >> >     Logical Minimum (0)
> >> >     Logical Maximum (1)
> >> >     Report Size (1)
> >> >     Report Count (2)
> >> >     Input (2)
> >> >     Report Count (6)
> >> >     Input (3)
> >> >     Usage Page (Generic Desktop)
> >> >     Usage (Generic Desktop.X)
> >> >     Usage (Generic Desktop.Y)
> >> >     Logical Minimum (129)
> >> >     Logical Maximum (127)
> >> >     Report Size (8)
> >> >     Report Count (2)
> >> >     Input (6)
> >> >     Report Size (8)
> >> >     Report Count (5)
> >> >     Input (3)
> >> >   End Collection (0)
> >> >   Usage Page (Vendor Defined Page 1)
> >> >   Usage (Vendor Defined Page 1.Vendor Usage 1)
> >> >   Report ID (14)
> >> >   Usage (Vendor Defined Page 1.00c5)
> >> >
> >> > I noticed  you still have:
> >> >
> >> > [    0.069726] Dynamic Preempt: full
> >> >
> >> > Can you change that in .config to:
> >> >
> >> > CONFIG_PREEMPT_VOLUNTARY=y
> >> 
> >> Strange, I did change that config.  Do I need to change another config for it to take effect?
> >
> > Probably not.
> >
> >> CONFIG_PREEMPT_BUILD=y
> >> # CONFIG_PREEMPT_NONE is not set
> >> CONFIG_PREEMPT_VOLUNTARY=y
> >> CONFIG_PREEMPT=y
> >> # CONFIG_PREEMPT_LAZY is not set
> >> CONFIG_PREEMPT_COUNT=y
> >> CONFIG_PREEMPTION=y
> >> CONFIG_PREEMPT_DYNAMIC=y
> >> CONFIG_PREEMPT_RCU=y
> >> CONFIG_PREEMPT_NOTIFIERS=y
> >> # CONFIG_PREEMPT_TRACER is not set
> >> # CONFIG_PREEMPTIRQ_DELAY_TEST is not set
> >> 
> >> >
> >> > Also let's add on top of everything one more hack patch, just in case ;-)
> >> >
> >> > diff --git a/drivers/i2c/i2c-core-acpi.c b/drivers/i2c/i2c-core-acpi.c
> >> > index ed90858a27b7..0297ebedb802 100644
> >> > --- a/drivers/i2c/i2c-core-acpi.c
> >> > +++ b/drivers/i2c/i2c-core-acpi.c
> >> > @@ -371,7 +371,7 @@ static const struct acpi_device_id 
> >> > i2c_acpi_force_100khz_device_ids[] = {
> >> >  	 * a 400KHz frequency. The root cause of the issue is not known.
> >> >  	 */
> >> >  	{ "DLL0945", 0 },
> >> > -	{ "ELAN06FA", 0 },
> >> > +//	{ "ELAN06FA", 0 },
> >> >  	{}
> >> >  };
> >> 
> >> The "DSDT uses known not-working I2C bus speed 400000, forcing it to 100000" message is now gone, but the touchpad still doesn't function (full log attached).
> >
> > Thanks again! It still fails in completely unexpected place I wonder if the
> > BPF quirsk somehow could affect it?
> >
> > Could you still try with CONFIG_HID_BPF=n and see if there is any change?
> 
> I applied that config change and saw the same touchpad failure (full log attached).

Just to confirm, after you applied the change, compiled a kernel, the change is
visible in .config in the kernel output folder (by default it's the same where
kernel sources are located for compilation), correct?

-- 
With Best Regards,
Andy Shevchenko