Re: [PATCH v9 00/12] mfd: nct6694: Refactor transport layer and add HIF (eSPI) support

[Ming Yu]

Hi Lee,

Thanks for the review. I have replied to each report in its thread. In short:

 - 6/12 and 9/12: The report is valid, but the issue predates this
   series. v10 will add a separate fix with a Fixes tag, and the two
   patches will be rebased on top of it.

 - 12/12: This is the intended behaviour, so no change is planned.

The planned fix for 6/12 and 9/12 is:

  mfd: nct6694: Drop the unused IRQ enable mask

  The .irq_enable and .irq_disable callbacks only update the
  irq_enable bitmask under irq_lock, which is a spinlock_t. Nothing
  ever reads that bitmask, so the callbacks do not mask anything. They
  also take irq_lock while the IRQ core holds desc->lock, a raw
  spinlock. On PREEMPT_RT this is an invalid wait context.

  The fix removes both callbacks, along with irq_enable and irq_lock,
  and keeps IRQCHIP_SKIP_SET_WAKE. Without .irq_disable, the IRQ core
  falls back to lazy disable, and handle_simple_irq() keeps a disabled
  interrupt pending instead of calling its handler. The behaviour is
  therefore unchanged.

  Fixes: 51dad33ede63 ("mfd: Add core driver for Nuvoton NCT6694")

I went with removing the callbacks rather than converting irq_lock to
a raw_spinlock_t, because the bitmask it protects is never used.
Please let me know if you would prefer the conversion instead.

Best regards,
Ming

Lee Jones <lee@xxxxxxxxxx> 於 2026年10月20日週二 下午6:27寫道：
>
> On Tue, 13 Oct 2026, a0282524688@xxxxxxxxx wrote:
>
> > From: Ming Yu <a0282524688@xxxxxxxxx>
> >
> > The Nuvoton NCT6694 is a peripheral expander that provides GPIO, I2C,
> > CAN-FD, Watchdog, HWMON, PWM, and RTC sub-devices. Currently, the
> > driver only supports USB as the host transport interface.
> >
> > This series refactors the NCT6694 MFD driver to support multiple
> > transport backends and adds a Host Interface (HIF) transport driver
> > that communicates over eSPI using Super-I/O shared memory.
> >
> > Patches 1-4 fix pre-existing bugs in the current driver. They carry a
> > Fixes tag and can be picked up independently of the rest of the series.
> >
> > Patches 5-11 isolate the USB transport, extract the transport-agnostic
> > core into nct6694-core.c and wrap the firmware command interface behind
> > regmap, so that the sub-device drivers no longer depend on the
> > transport. Patch 12 adds the HIF transport on top.
>
> Please fix or respond to the Sashkio reviews on patches 6, 9 and 12.
>
> --
> Lee Jones