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

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

On Tue, Jan 27, 2026 at 03:43:57PM +0100, Mika Westerberg wrote:
> On Tue, Jan 27, 2026 at 05:56:37AM -0500, correctmost wrote:

...

> > > Okay can you set CONFIG_INTEL_IDMA64=n in .config? That should prevent it
> > > from loading. Keep the rest as it was.
> > 
> > That change makes the IRQ message go away and the touchpad seems to work
> > fine in my desktop environment (log attached).
> > 
> > These are the config changes that I tested with:
> > - CONFIG_I2C_DESIGNWARE_CORE=m
> > - CONFIG_I2C_DESIGNWARE_PLATFORM=m
> > - CONFIG_INTEL_IDMA64=n
> 
> Okay thanks it looks good to me too.
> 
> I tried to go through the datasheets again but could not figure why the
> LPSS I2C IP would keep the interrupt asserted.

We can try to dig something internally, but it's another story.

> However, I think we can
> hack^Hwork this around by simply not creating the IDMA64 device at all for
> I2C. This should be fine to do because I2C is really not using DMA in the
> first place so this is kind of just wasting "memory". So something like
> below.
> 
> Please re-enable CONFIG_INTEL_IDMA64=m and the rest and try if this makes
> it work without the irq splat. And if it does please try with the
> "original" arch setup and see if that works too (keeping the patch applied
> of course).
> 
> Andy, what's your thoughts on this?

Fun fact, that I was thinking about the similar approach as in "don't enumerate
DMA for I²C LPSS controllers" a few hours ago (and for the record, sometime ago
but I don't remember why that time).

So I'm fine, but we need to put also a big comment with the reference to this
discussion or so.

...

Btw, do we have an i2c alert interrupt here? Might be it's somehow related?

-- 
With Best Regards,
Andy Shevchenko