linux-kernel - Re: [PATCH v1 1/1] PCI: brcmstb: Use GENMASK() as _

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Message-ID: <YXkphydcdD9giKqs@smile.fi.intel.com>
Date:   Wed, 27 Oct 2021 13:27:19 +0300
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Krzysztof Wilczyński <kw@...ux.com>
Cc:     bcm-kernel-feedback-list@...adcom.com,
        linux-rpi-kernel@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Jim Quinlan <jim2101024@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v1 1/1] PCI: brcmstb: Use GENMASK() as __GENMASK() is for
 internal use only

On Wed, Oct 27, 2021 at 12:00:16PM +0200, Krzysztof Wilczyński wrote:
> > Use GENMASK() as __GENMASK() is for internal use only.
> 
> To add, for posterity, that using __GENMASK() bypasses the
> GENMASK_INPUT_CHECK() macro that adds extra validation.

In general, yes, but here we have a variable...

> > -	u32 val = __GENMASK(31, msi->legacy_shift);
> > +	u32 val = GENMASK(31, msi->legacy_shift);

...which make me thing that the whole construction is ugly
(and I truly believe the code is very ugly here, because
 the idea behind GENMASK() is to be used with constants).

So, what about

	u32 val = ~(BIT(msi->legacy_shift) - 1);

instead?

> Thank you!
> 
> Reviewed-by: Krzysztof Wilczyński <kw@...ux.com>

Thank you!

-- 
With Best Regards,
Andy Shevchenko