linux-kernel - Re: [PATCH v3 4/8] i2c: riic: Use GENMASK() macro for bitmask definitions

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Message-ID: <CA+V-a8u03DjtUFf8j_y+bgbotiRt3fbBZGhrCTNqSVSdD8D8Uw@mail.gmail.com>
Date: Thu, 2 Jan 2025 08:53:14 +0000
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Andi Shyti <andi.shyti@...nel.org>, David Laight <david.laight.linux@...il.com>
Cc: Chris Brandt <chris.brandt@...esas.com>, Geert Uytterhoeven <geert+renesas@...der.be>, 
	Wolfram Sang <wsa+renesas@...g-engineering.com>, Philipp Zabel <p.zabel@...gutronix.de>, 
	linux-renesas-soc@...r.kernel.org, linux-i2c@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Biju Das <biju.das.jz@...renesas.com>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>, 
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: Re: [PATCH v3 4/8] i2c: riic: Use GENMASK() macro for bitmask definitions

Hi Andi,

On Wed, Jan 1, 2025 at 12:11 PM David Laight
<david.laight.linux@...il.com> wrote:
>
> On Fri, 27 Dec 2024 11:51:50 +0000
> Prabhakar <prabhakar.csengg@...il.com> wrote:
>
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > Replace raw bitmask values with the `GENMASK()` macro in the `i2c-riic`
> > driver to improve readability and maintain consistency.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
> > Reviewed-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
> > Tested-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
> > Tested-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> > Reviewed-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
> > ---
> > v2->v3
> > - Collected RB and tested tags
> >
> > v1->v2
> > - Collected RB tag from Geert
> > ---
> >  drivers/i2c/busses/i2c-riic.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-riic.c b/drivers/i2c/busses/i2c-riic.c
> > index 954e066d61a8..ddae4b74a86b 100644
> > --- a/drivers/i2c/busses/i2c-riic.c
> > +++ b/drivers/i2c/busses/i2c-riic.c
> > @@ -55,7 +55,7 @@
> >  #define ICCR2_RS     BIT(2)
> >  #define ICCR2_ST     BIT(1)
> >
> > -#define ICMR1_CKS_MASK       0x70
> > +#define ICMR1_CKS_MASK       GENMASK(6, 4)
> >  #define ICMR1_BCWP   BIT(3)
> >  #define ICMR1_CKS(_x)        ((((_x) << 4) & ICMR1_CKS_MASK) | ICMR1_BCWP)
>
> I'm really not at all sure how this makes it 'more readable'.
> Call me 'old fashioned' but I like hex constants - especially for bytes.
> In this case it might be best to be consistent with the hardware datasheet.
>
Let me know if you dont accept such patches. I'll drop it from the next version.

> Pretty much the only time I've actually used anything like BIT() was
> for a spec that numbered the bits from 1 to 32 with bit 1 being the most
> significant.
>
> >
> > @@ -73,7 +73,7 @@
> >
> >  #define ICSR2_NACKF  BIT(4)
> >
> > -#define ICBR_RESERVED        0xe0 /* Should be 1 on writes */
> > +#define ICBR_RESERVED        GENMASK(7, 5) /* Should be 1 on writes */
>
>         'Should all be set on writes' ?
>
Yes.

Cheers,
Prabhakar