linux-kernel - Re: [PATCH v2 04/15] spi: Replace open coded spi_controller_xfer

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Message-ID: <ZK11flZf/1grJ1Bd@smile.fi.intel.com>
Date:   Tue, 11 Jul 2023 18:30:06 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Cristian Ciocaltea <cristian.ciocaltea@...labora.com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        Amit Kumar Mahapatra via Alsa-devel 
        <alsa-devel@...a-project.org>,
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        Tharun Kumar P <tharunkumar.pasumarthi@...rochip.com>,
        Vijaya Krishna Nivarthi <quic_vnivarth@...cinc.com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, linux-spi@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
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        Richard Cochran <richardcochran@...il.com>
Subject: Re: [PATCH v2 04/15] spi: Replace open coded
 spi_controller_xfer_timeout()

On Tue, Jul 11, 2023 at 03:14:54PM +0100, Mark Brown wrote:
> On Tue, Jul 11, 2023 at 02:01:13PM +0300, Andy Shevchenko wrote:
> > On Mon, Jul 10, 2023 at 06:30:32PM +0100, Mark Brown wrote:
> > > On Mon, Jul 10, 2023 at 06:49:21PM +0300, Andy Shevchenko wrote:
> 
> > > > + * Assume speed to be 100 kHz if it's not defined at the time of invocation.
> 
> > > You didn't mention this bit in the changelog, and I'm not 100% convinced
> > > it was the best idea in the first place.  It's going to result in some
> > > very big timeouts if it goes off, and we really should be doing
> > > validation much earlier in the process.
> 
> > Okay, let's drop this change.
> 
> Like I say we *should* be fine with the refactoring without this, or at
> least if it's an issue we should improve the validation.

For the speeds < 1000 Hz, this change will lead to the div by 0 crash.
It seems that the current code which this one removes is better than
the spi_controller_xfer_timeout() provides.

If anything, the spi_controller_xfer_timeout() should be improved first.
So, for now I drop this for sure. Maybe in the future we can come back
to it.

-- 
With Best Regards,
Andy Shevchenko