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

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

+Cc: Mika

On Mon, Jan 12, 2026 at 04:35:08PM +0200, Andy Shevchenko wrote:
> On Tue, Dec 16, 2025 at 12:57:10PM -0500, correctmost wrote:
> 
> > The following commit
> 
> No, it's false positive. The reality is that something else is going on
> there on this and other similar laptops.
> 
> > causes my Lenovo IdeaPad touchpad not to work when
> > kernel/drivers/dma/idma64.ko.zst is present in the initramfs image:
> > 
> > #regzbot introduced: 9140ce47872bfd89fca888c2f992faa51d20c2bc
> > 
> > "idma64: Don't try to serve interrupts when device is powered off"
> 
> So, the touchpad is an I²C device, which is connected to an Intel SoC.
> The I²C host controller is Synopsys DesignWare. On Intel SoCs the above
> mentioned IP is generated with private DMA engine, that's called Intel
> iDMA 64-bit. Basically it's two devices under a single PCI hood.
> The problem here is that when PCI device is in D3, both devices are
> powered off, but something sends an interrupt and it's not recognized
> being the one, send by a device (touchpad).
> 
> There is one of the following potential issues (or their combinations):
> 
> - the I²C host controller hardware got off too early
> - the line is shared with something else that generates interrupt storm
> - the BIOS does weird (wrong) things at a boot time, like not properly
>   shutting down and disabling interrupt sources; also may have wrong
>   pin control settings
> - the touchpad is operating on higher frequency like 400kHz (because
>   BIOS told to use that one instead of 100kHz) than the HW is designed
>   for and hence unreliable with all possible side effects
> - the touchpad firmware behaves wrongly on some sequences (see also
>   note about the bus speed above), try to upgrade touchpad FW
> 
> With my experience with the case of the above mentioned commit that it
> may be BIOS thingy. Also consider the bus speed, there are quirks in
> the kernel for that.
> 
> > Here are the related logs:
> > 
> > ---
> > 
> > irq 27: nobody cared (try booting with the "irqpoll" option)
> 
> Almost all below is not so interesting.
> 
> ...
> 
> > handlers:
> > [<00000000104a7621>] idma64_irq [idma64]
> > [<00000000bd8d08e9>] i2c_dw_isr
> > Disabling IRQ #27
> 
> Yes, this line at least shared between those two and might be more.
> 
> ...
> 
> > i2c_designware i2c_designware.0: controller timed out
> > hid (null): reading report descriptor failed
> > i2c_hid_acpi i2c-ELAN06FA:00: can't add hid device: -110
> > i2c_hid_acpi i2c-ELAN06FA:00: probe with driver i2c_hid_acpi failed with error -110
> 
> Yes, sounds familiar with the speed settings. Try to down it to 100kHz in case
> it's confirmed to be 400kHz.
> 
> > ---
> > 
> > Hardware info:
> > - Lenovo 16" IdeaPad Slim 5 - 16IRU9
> >   - Hardware name: LENOVO 83FW/LNVNB161216, BIOS PFCN14WW 09/20/2024
> >   - ELAN06FA:00 04F3:327E Touchpad
> > 
> > Steps to reproduce:
> > - Cold boot the laptop on Arch Linux
> > 
> > The bug is still present with the 6.19.0-rc1-1-git kernel.
> > 
> > The bisected commit is from March 2024, but I only recently noticed the issue
> > because the initramfs images on Arch Linux now include these additional
> > drivers (as of November 2025):
> > - kernel/drivers/dma/idma64.ko.zst
> > - kernel/drivers/mfd/intel-lpss-pci.ko.zst
> > - kernel/drivers/mfd/intel-lpss.ko.zst
> > 
> > Two other users have reported the issue on the Arch Linux and CachyOS forums,
> 
> Any pointers to that thread, please?
> 
> > so I don't think this is a hardware issue with my individual laptop.
> 
> I don't know how this conclusion is came here. You mean HW as laptop model?
> But are the involved components the same (I²C host controller + touchpad)?

-- 
With Best Regards,
Andy Shevchenko