Related - I2C Trackpads and other IRQ mechanisms have trouble on Intel Hybrid platforms. Handle them with lpmd

[jrelvas-ipc]

One of the biggest power managements issues I've noticed with Alder Lake/Raptor Lake platforms is IRQs getting suboptimal core pinning.

A great example with this is I2C trackpads/touchpads, as seen on https://bugzilla.kernel.org/show_bug.cgi?id=218169.

Moving the finger on the touchpad generates two kinds of interrupts, which are pinned to topologically unrelated cores by the kernel (one interrupt is handled by a P core, another is handled by an E core). This has a very big hit on power consumption.

intel-lpmd could be used in cases like these to pin interrupts to the most optimal cores:

• When on low-power mode, avoid handling interrupts in parked cores. This ensures that the cores actually remain parked.
• Avoid handling related interrupts outside of the same cluster. (P-core, E-core(1-4), E-core(5,8), etc.). This ensures that consistent actions such as using the trackpad do not wake up more than one cluster.

[spandruvada]

We are migrating interrupts from parked cores. The second part we need to think, how we can do,