linux-kernel - Re: [PATCH v4 8/8] linux/log2.h: Use roundup/dow_pow

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Message-ID: <d1c87c83f38e74f0c6b0692248fe88dfd2bdec3e.camel@suse.de>
Date:   Tue, 03 Dec 2019 17:06:43 +0100
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Andrew Murray <andrew.murray@....com>,
        Marc Zyngier <maz@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Hanjun Guo <guohanjun@...wei.com>,
        Sudeep Holla <sudeep.holla@....com>,
        Tariq Toukan <tariqt@...lanox.com>,
        Frank Rowand <frowand.list@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "maintainer:BROADCOM BCM7XXX ARM ARCHITECTURE" 
        <bcm-kernel-feedback-list@...adcom.com>,
        Eric Anholt <eric@...olt.net>,
        Stefan Wahren <wahrenst@....net>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Christoph Hellwig <hch@....de>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
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        Phil Elwell <phil@...pberrypi.org>,
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        PCI <linux-pci@...r.kernel.org>,
        "moderated list:BROADCOM BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@...ts.infradead.org>,
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        Len Brown <lenb@...nel.org>,
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        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        Linux IOMMU <iommu@...ts.linux-foundation.org>
Subject: Re: [PATCH v4 8/8] linux/log2.h: Use roundup/dow_pow_two() on 64bit
 calculations

Hi Rob,

On Tue, 2019-12-03 at 09:53 -0600, Rob Herring wrote:
> On Tue, Dec 3, 2019 at 5:48 AM Nicolas Saenz Julienne
> <nsaenzjulienne@...e.de> wrote:
> > The function now is safe to use while expecting a 64bit value. Use it
> > where relevant.
> 
> What was wrong with the existing code? This is missing some context.

You're right, I'll update it.

For most of files changed the benefit here is factoring out a common pattern
using the standard function roundup/down_pow_two() which now provides correct
64bit results.

As for of/device.c and arm64/iort.c it's more of a readability enhancement. I
consider it's easier to understand than the current calculation as it abstracts
the math.

> > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
> > ---
> >  drivers/acpi/arm64/iort.c                        | 2 +-
> >  drivers/net/ethernet/mellanox/mlx4/en_clock.c    | 3 ++-
> >  drivers/of/device.c                              | 3 ++-
> 
> In any case,
> 
> Acked-by: Rob Herring <robh@...nel.org>
> 

Thanks!

Regards,
Nicolas


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