Re: [PATCH] iio: adc: fsl-imx25-gcq: check the return value of the

[Andy Shevchenko]

On Thu, Oct 22, 2026 at 04:24:45AM +0530, Arnav Kapoor wrote:
> The driver ignores the return value of all the regmap accesses. If one
> of them fails, e.g. because the memory mapped registers can't be
> accessed, the driver just continues with an undefined state.

Can MMIO actually fail? It can give invalid values (due to HW being off or
wrong MMIO window). It can give a page fault, or some other error in HW,
but the read itself most likely never fails.

> The most severe case is the read of the FIFO in
> mx25_gcq_get_raw_value(): the destination variable is not initialized,
> so a failed read leaks uninitialized stack memory to userspace.
> 
> Check the return value of all the register accesses and propagate the
> errors to the caller. In the interrupt handler, where there is not much
> that can be done about a failed access, just don't use the content of
> the status register if it can't be read.

I consider this change an unneeded churn until you come up with real life
example of how MMIO fails (at least on this platform, not exactly with this
driver).

Yes, I aware that checking for error codes of regmap is a good manners and
style in general, but would we do jsut that in a standalone change?

-- 
With Best Regards,
Andy Shevchenko