Re: [Outreachy kernel] [PATCH] Staging: mt29f_spinand: Replace udelay function with usleep_range

[Eva Rachel Retuya <eraretuya@gmail.com>]

On Fri, Oct 30, 2015 at 10:32:40PM +0100, Arnd Bergmann wrote:
> On Sunday 25 October 2015 01:24:51 Eva Rachel Retuya wrote:
> > Use 'usleep_range' instead of 'udelay' to elapse time. For
> > spinand_reset, define the upper limit by a factor of 2 to keep the wait
> > short while still allowing a "good enough" range for wakeup. Define the
> > range 250us - 1ms for spinand_cmdfunc to provide enough leeway before
> > issuing spinand_reset. Checkpatch found this issue.
> > 
> > CHECK: usleep_range is preferred over udelay; see
> > Documentation/timers/timers-howto.txt
> 
> You are missing here an explanation about how you verified that the
> conversion is safe: Are you sure that the spinand_reset() function
> is never called from "atomic" context?
> 
> 	Arnd

Please correct me if I'm wrong. I look up similar patches before this
and scanned the code taking into consideration what was discussed. In
this case, I didn't see any indication that it is not allowed to sleep
and also by looking at the probe function containing "devm_kzalloc(..., GFP_KERNEL). The caller/s of the reset function does not indicate whether it is on "lock status" and from my analysis, the use of "udelay()" simply wants to elapse time before proceeding.

Do you think it operates in atomic context?

Eva