linux-kernel - RE: [PATCH v2 2/3] ACPI: PMIC: Replace open coded be16_to

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Date:   Wed, 31 Aug 2022 10:06:09 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Mika Westerberg' <mika.westerberg@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>
CC:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, Andy Shevchenko <andy@...nel.org>
Subject: RE: [PATCH v2 2/3] ACPI: PMIC: Replace open coded be16_to_cpu()

From: Mika Westerberg
> Sent: 31 August 2022 10:49
> 
> On Wed, Aug 31, 2022 at 11:37:21AM +0200, Hans de Goede wrote:
> > Hi,
> >
> > On 8/31/22 11:34, Andy Shevchenko wrote:
> > > On Wed, Aug 31, 2022 at 08:43:54AM +0300, Mika Westerberg wrote:
> > >> On Tue, Aug 30, 2022 at 08:11:54PM +0300, Andy Shevchenko wrote:
> > >>> -#define VR_MODE_DISABLED        0
> > >>> -#define VR_MODE_AUTO            BIT(0)
> > >>> -#define VR_MODE_NORMAL          BIT(1)
> > >>> -#define VR_MODE_SWITCH          BIT(2)
> > >>> -#define VR_MODE_ECO             (BIT(0)|BIT(1))
> > >>> +#define PMIC_REG_MASK		GENMASK(11, 0)
> > >>> +
> > >>> +#define VR_MODE_DISABLED        (0 << 0)
> > >>> +#define VR_MODE_AUTO            (1 << 0)
> > >>> +#define VR_MODE_NORMAL          (2 << 0)
> > >>> +#define VR_MODE_ECO             (3 << 0)
> > >>> +#define VR_MODE_SWITCH          (4 << 0)
> > >>
> > >> IMHO this one is worse than what it was.
> > >
> > > I'm not sure why. Here is obvious wrong use of BIT() macro against
> > > plain numbers. I can split it into a separate change with an explanation
> > > of why it's better. But I think it doesn't worth the churn.
> >
> > FWIW I'm with Andy here, the VR_MODE_ECO clearly is trying
> > to just say 3, so this is just a plain enum for values 0-4 and
> > as such should not use the BIT macros.
> 
> Yeah, enum would look better but the << 0 just makes me confused ;-)

No idea what that code is doing.
The values are all used to initialise a .bit structure member.
So maybe BIT() is right.
The _ECO value isn't used at all.

Deeper analysis may be needed.

	David

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