linux-kernel - Re: [PATCH 4/4] soundwire: stream: Tidy do_bank

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Date:   Fri, 2 Jun 2023 08:38:10 +0000
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
CC:     <vkoul@...nel.org>, <yung-chuan.liao@...ux.intel.com>,
        <sanyog.r.kale@...el.com>, <alsa-devel@...a-project.org>,
        <linux-kernel@...r.kernel.org>, <patches@...nsource.cirrus.com>
Subject: Re: [PATCH 4/4] soundwire: stream: Tidy do_bank_switch error messages

On Thu, Jun 01, 2023 at 11:34:10AM -0500, Pierre-Louis Bossart wrote:
> On 6/1/23 11:16, Charles Keepax wrote:
> > Every error path in do_bank_switch prints an error message so there is no
> > need for the callers to also print error messages. Indeed in multi-master
> > cases these extra messages are confusing because they print out against a
> > random bus device whereas the do_bank_switch messages print against the bus
> > that actually failed.
> 
> Errm, what?
> 
> There is no way to know which bus failed in multi-master mode, and the
> 'stream' can span multiple buses so the use of pr_err was intentional.

Apologies this is the commit message not quite keeping pace with
the code base. Originally when I wrote the patch the error
message after do_bank_switch were a "dev_err(bus->dev", that was
then fixed up in commit d014688eb373 ("soundwire: stream: remove
bus->dev from logs on multiple buses").

> There's just no other way to report issues, and I don't see why one
> would remove such logs and fail silently.
> 
> I just don't get what you are trying to address.
>

The current code would say produce something like:

Bank switch failed: -5
_sdw_prepare_stream: do_bank_switch failed: -5

I am sensing you are keen to keep both error messages, so fair
enough I will drop that. Although worth noting originally before
that patch I mention above this would have been:

Bank switch failed: -5
do_bank_switch failed: -5

Which is really what I was attempting to address, that is clearly
redundant. Now with the addition of the function in the print I
guess it is slightly less redundant.

> > This also allows clean up of a couple of if's and variable initialisations
> > that were only there to silence potentially uninitialised variable
> > warnings on the bus variable.
> 
> That should be a separate patch IMHO.
> 

I will trim the patch down to leave the duplicate error messages
and just remove those bits.

Thanks,
Charles