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Message-ID: <4d8d18af22d6dcd122bc9b4d9c2bd49e8443c746.camel@suse.de>
Subject: Re: [PATCH v2 10/11] arm64: edit zone_dma_bits to fine tune
 dma-direct min mask
From:   Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
To:     Christoph Hellwig <hch@lst.de>
Cc:     catalin.marinas@arm.com, wahrenst@gmx.net, marc.zyngier@arm.com,
        robh+dt@kernel.org, Robin Murphy <robin.murphy@arm.com>,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-arch@vger.kernel.org, iommu@lists.linux-foundation.org,
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        linux-kernel@vger.kernel.org, phill@raspberryi.org,
        f.fainelli@gmail.com, will@kernel.org, eric@anholt.net,
        mbrugger@suse.com, linux-rpi-kernel@lists.infradead.org,
        akpm@linux-foundation.org, frowand.list@gmail.com,
        m.szyprowski@samsung.com
Date:   Mon, 26 Aug 2019 13:08:50 +0200
In-Reply-To: <20190826070633.GB11331@lst.de>
References: <20190820145821.27214-1-nsaenzjulienne@suse.de>
         <20190820145821.27214-11-nsaenzjulienne@suse.de>
         <20190826070633.GB11331@lst.de>
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On Mon, 2019-08-26 at 09:06 +0200, Christoph Hellwig wrote:
> On Tue, Aug 20, 2019 at 04:58:18PM +0200, Nicolas Saenz Julienne wrote:
> > -	if (IS_ENABLED(CONFIG_ZONE_DMA))
> > +	if (IS_ENABLED(CONFIG_ZONE_DMA)) {
> >  		arm64_dma_phys_limit =3D max_zone_dma_phys();
> > +		zone_dma_bits =3D ilog2((arm64_dma_phys_limit - 1) &
> > GENMASK_ULL(31, 0)) + 1;
>
Hi Christoph,
thanks for the rewiews.

> This adds a way too long line.

I know, I couldn't find a way to split the operation without making it even
harder to read. I'll find a solution.

> I also find the use of GENMASK_ULL
> horribly obsfucating, but I know that opinion is't shared by everyone.

Don't have any preference so I'll happily change it. Any suggestions? Using=
 the
explicit 0xffffffffULL seems hard to read, how about SZ_4GB - 1?


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