linux-kernel - Re: [PATCH v2 03/15] spi: Replace if-else-if by bitops and multiplications

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Message-ID: <24e71654-bc79-42ac-86d1-4e6100f6893a@sirena.org.uk>
Date:   Mon, 10 Jul 2023 17:56:59 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Cristian Ciocaltea <cristian.ciocaltea@...labora.com>,
        Yang Yingliang <yangyingliang@...wei.com>,
        Amit Kumar Mahapatra via Alsa-devel 
        <alsa-devel@...a-project.org>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        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,
        linux-amlogic@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
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        linux-riscv@...ts.infradead.org,
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        Sanjay R Mehta <sanju.mehta@....com>,
        Radu Pirea <radu_nicolae.pirea@....ro>,
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        Alain Volmat <alain.volmat@...s.st.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Max Filippov <jcmvbkbc@...il.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Richard Cochran <richardcochran@...il.com>
Subject: Re: [PATCH v2 03/15] spi: Replace if-else-if by bitops and
 multiplications

On Mon, Jul 10, 2023 at 06:49:20PM +0300, Andy Shevchenko wrote:

> -		if (xfer->bits_per_word <= 8)
> -			maxsize = maxwords;
> -		else if (xfer->bits_per_word <= 16)
> -			maxsize = 2 * maxwords;
> -		else
> -			maxsize = 4 * maxwords;
> -
> +		maxsize = maxwords * roundup_pow_of_two(BITS_TO_BYTES(xfer->bits_per_word));

This will change the behaviour if bits_per_word is more than 32.  That
is validated out elsewhere but I shouldn't have had to go around
checking the code to confirm that this is the case.  This is the sort of
thing that should be highlighted when doing this sort of edge case
stylistic change.

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