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

From: Florian Fainelli
Date: Wed Mar 13 2024 - 15:36:37 EST

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.


In this case we should return ret when:

ret is 0
OR
when ret is not -EOPNOTSUPP or -ENOTSUPP.

So if we get either of the two we _won't_ return and continue forward.

From looking at just this, spi_mem_exec_op() only returns -EOPNOTSUPP so
far since it has:

if (!spi_mem_internal_supports_op(mem, op))
return -EOPNOTSUPP;

But then looking further, it has:

ret = spi_sync(mem->spi, &msg);

if (ret)
return ret;

spi_sync() can return -ENOTSUPP if it goes via __spi_async(). I suppose
we would need to fix that if we want consistent return codes. But that
isn't a problem this patch should fix. So with the merge conflict fixed
up,

Thanks, although as I replied to Mark in the other branch of the thread, since this is a regression affecting v6.8, would not we want it to be fast tracked, and not based upon for-next?


Reviewed-by: Pratyush Yadav <pratyush@xxxxxxxxxx>


--
Florian

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