Re: [PATCH] spi: Fix error code checking in spi_mem_exec_op()

[Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>]

On 3/13/24 12:34, Florian Fainelli wrote:
> On 3/13/24 12:29, Pratyush Yadav wrote:
> > On Wed, Mar 13 2024, Florian Fainelli wrote:
> >
> > > On 3/13/24 11:28, Pratyush Yadav wrote:
> > > > On Wed, Mar 13 2024, Michael Walle wrote:
> > > >
> > > > > On Wed Mar 13, 2024 at 6:10 PM CET, Florian Fainelli wrote:
> > > > > > After commit cff49d58f57e ("spi: Unify error codes by replacing 
> > > > > > -ENOTSUPP with
> > > > > > -EOPNOTSUPP"), our SPI NOR flashes would stop probing with the 
> > > > > > following
> > > > > > visible in the kernel log:
> > > > > >
> > > > > > [    2.196300] brcmstb_qspi f0440920.qspi: using bspi-mspi mode
> > > > > > [    2.210295] spi-nor: probe of spi1.0 failed with error -95
> > > > > >
> > > > > > It turns out that the check in spi_mem_exec_op() was changed to check
> > > > > > for -ENOTSUPP (old error code) or -EOPNOTSUPP (new error code), 
> > > > > > but this
> > > > > > means that for drivers that were converted, the second condition 
> > > > > > is now
> > > > > > true, and we stop falling through like we used to. Fix the error to
> > > > > > check for neither error being neither -ENOTSUPP *nor* -EOPNOTSUPP.
> > > > > >
> > > > > > Fixes: cff49d58f57e ("spi: Unify error codes by replacing 
> > > > > > -ENOTSUPP with -EOPNOTSUPP")
> > > > > > Signed-off-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>
> > > > > > Change-Id: I4159811f6c582c4de2143382473d2000b8755872
> > > > >
> > > > > Ha, thank you!
> > > > >
> > > > > Reviewed-by: Michael Walle <mwalle@xxxxxxxxxx>
> > > > >
> > > > > FWIW in next, there is commit
> > > > > e63aef9c9121e ("spi: spi-mem: add statistics support to ->exec_op() 
> > > > > calls")
> > > > > that probably will conflict with this one.
> > > > >
> > > > > Also, - not for this patch - but with that logic, spi_mem_exec_op()
> > > > > might return EOPNOTSUPP *or* ENOTSUPP, even for drivers which might
> > > > > still return ENOTSUPP, because there is one condition in
> > > > > spi_mem_exec_op() which will always return EOPNOTSUPP. That is
> > > > > somewhat confusing, no?
> > > > I agree. I suppose it would be better to do:
> > > >       if (!ret)
> > > >          return 0;
> > > >       if (ret == -ENOTSUPP || ret == -EOPNOTSUPP)
> > > >          return -EOPNOTSUPP;
> > >
> > > But with e63aef9c9121e ("spi: spi-mem: add statistics support to 
> > > ->exec_op()
> > > calls") applied, would not that mean duplicating the statistics 
> > > gathering, or
> > > were the statistics gathering only intended for when ret == 0?
> >
> > Hmm, I didn't properly understand this. Ignore my suggestion. Your patch
> > does the right thing.
>
> What I meant is that e63aef9c9121e will increment statistics not just 
> when we return 0 from ctlr->mem_ops->exec_op, but also if we return 
> -ENOTSUPP or -EOPNOTSUPP, and I am  not sure if this is exactly what is 
> intended. But this is somewhat orthogonal.

It looks like the handling of a non-zero return code will fall either in 
the -ETIMEDOUT category, or in the general category of an error. I 
suppose there is a question whether a operation that could not be 
supported should fall in the "error" category.
--
Florian

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