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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Wed, 5 Dec 2018 10:11:34 +0100
Message-ID: <CAMuHMdXS_039E6F3=+UgfE_KgJcwmVvA-zPraOiQPUXMEwck2A@mail.gmail.com>
Subject: Re: [PATCH v2 1/2] spi: Add Renesas R-Car Gen3 RPC SPI controller driver
To:     masonccyang@mxic.com.tw
Cc:     Marek Vasut <marek.vasut@gmail.com>,
        Boris Brezillon <boris.brezillon@bootlin.com>,
        Mark Brown <broonie@kernel.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Simon Horman <horms@verge.net.au>, juliensu@mxic.com.tw,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        linux-spi <linux-spi@vger.kernel.org>, zhengxunli@mxic.com.tw
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Mason,

On Wed, Dec 5, 2018 at 8:44 AM <masonccyang@mxic.com.tw> wrote:
> > "Marek Vasut" <marek.vasut@gmail.com>
> > 2018/12/05 上午 10:04
> > On 12/03/2018 10:18 AM, Mason Yang wrote:
> > > Add a driver for Renesas R-Car Gen3 RPC SPI controller.
> > >
> > > Signed-off-by: Mason Yang <masonccyang@mxic.com.tw>

> > > +static u8 rpc_bits_xfer(u32 nbytes)
> > > +{
> > > +   if (nbytes > 4)
> > > +      nbytes = 4;
> >
> > Use clamp() ?
> >
>
> nbytes = clamp(nbytes, 1, 4);
>
> got many warnings, something like,
> ./include/linux/kernel.h:845:29: warning: comparison of distinct pointer types lacks a cast

You can either make the constants unsigned (1U and 4U), or
use clamp_t(u32, ...).

> > > +         rpc->smenr |= RPC_SMENR_SPIDE(rpc_bits_xfer
> > > +               (op->data.nbytes)) | RPC_SMENR_SPIDB
> > > +               (fls(op->data.buswidth >> 1));
> >
> > Drop parenthesis around fls()
>
> ?
> no way.

Please split the line before RPC_SMENR_SPIDB, and join the next line
with the parameters, so it becomes obvious the parentheses are needed
because RPC_SMENR_SPIDB() is a macro taking parameters.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds