linux-kernel - Re: [PATCH] spi: Fix error code checking in spi_mem_exec

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Message-ID: <mafs0o7bic7fs.fsf@kernel.org>
Date: Wed, 13 Mar 2024 19:28:39 +0100
From: Pratyush Yadav <pratyush@...nel.org>
To: "Michael Walle" <mwalle@...nel.org>
Cc: "Florian Fainelli" <florian.fainelli@...adcom.com>,
  <linux-spi@...r.kernel.org>,  "Mark Brown" <broonie@...nel.org>,  "Miquel
 Raynal" <miquel.raynal@...tlin.com>,  "Mika Westerberg"
 <mika.westerberg@...ux.intel.com>,  "Chia-Lin Kao (AceLan)"
 <acelan.kao@...onical.com>,  "open list" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] spi: Fix error code checking in spi_mem_exec_op()

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@...adcom.com>
>> Change-Id: I4159811f6c582c4de2143382473d2000b8755872
>
> Ha, thank you!
>
> Reviewed-by: Michael Walle <mwalle@...nel.org>
>
> 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;

-- 
Regards,
Pratyush Yadav