linux-kernel - Re: [PATCH v8 5/5] spi: dw: Round of n

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Date:   Fri, 21 Apr 2023 23:18:16 +0530
From:   Joy Chakraborty <joychakr@...gle.com>
To:     Serge Semin <fancer.lancer@...il.com>
Cc:     David Laight <David.Laight@...lab.com>,
        Mark Brown <broonie@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...el.com>,
        "linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "manugautam@...gle.com" <manugautam@...gle.com>,
        "rohitner@...gle.com" <rohitner@...gle.com>
Subject: Re: [PATCH v8 5/5] spi: dw: Round of n_bytes to power of 2

On Fri, Apr 21, 2023 at 10:45 PM Serge Semin <fancer.lancer@...il.com> wrote:
>
> On Fri, Apr 21, 2023 at 10:40:44PM +0530, Joy Chakraborty wrote:
> > On Fri, Apr 21, 2023 at 10:18 PM Serge Semin <fancer.lancer@...il.com> wrote:
> > >
> > > On Fri, Apr 21, 2023 at 04:39:30PM +0000, David Laight wrote:
> > > > From: Joy Chakraborty
> > > > > Sent: 21 April 2023 10:22
> > > > ...
> > > > > Sure, I can make the following change in the formatting and send the
> > > > > patch series:
> > > > >          dws->n_bytes =
> > > > >                  roundup_pow_of_two(DIV_ROUND_UP(transfer->bits_per_word,
> > > > >                                                  BITS_PER_BYTE));
> > > >
> > >
> > > > Won't checkpatch bleat about that?
> > >
> > > Why would it?
> >
> > I ran checkpatch on this and it seems to be fine with minor spacing changes.
>
> What spacing do you mean? No problem with the change as is:
> [fancer@...ilestation] kernel $ git show HEAD | grep -A1 -B2 roundup_pow_of_two
> -       dws->n_bytes = DIV_ROUND_UP(transfer->bits_per_word, BITS_PER_BYTE);
> +       dws->n_bytes =
> +               roundup_pow_of_two(DIV_ROUND_UP(transfer->bits_per_word,
> +                                               BITS_PER_BYTE));
> [fancer@...ilestation] kernel $ ./scripts/checkpatch.pl --git HEAD
> total: 0 errors, 0 warnings, 10 lines checked
>
> Commit e18b699257db ("spi: dw: Round of n_bytes to power of 2") has no obvious style problems and is ready for submission.
>
> -Serge(y)
>

Sorry for my error, it looks like my email client does not show it correctly.
What I was going to upload in V9 is the same as you mentioned.

Thanks
Joy
> >
> > >
> > > >
> > > > Is it ever actually valid for the caller to provide a
> > > > value that isn't 8, 16 or 32 ?
> > >
> > > Judging by this
> > > https://elixir.bootlin.com/linux/v6.3-rc7/source/drivers/spi/spi.c#L3630
> > > it is. SPI-controller also supports word lengths within the
> > > pre-synthesized range. So it's up to the SPI-peripherals and their
> > > protocols what word length to select.
> > >
> > > -Serge(y)
> > >
> > > >
> > > > I'm sure it looked as though some other lengths/counts
> > > > where likely to go badly wrong.
> > > >
> > > > I know there are times when it is useful to bit-bang 'odd'
> > > > numbers of bits - like command+address+delay for fast reads
> > > > but that is a sub-32bit transfer so (at least somewhere)
> > > > is 1 word but not all the bits.
> > > >
> > > >       David
> > > >
> > > > -
> > > > Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
> > > > Registration No: 1397386 (Wales)