From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@lst.de>
Date: Thu, 03 Sep 2020 16:12:52 +0000
Subject: Re: [PATCH 1/2] dma-mapping: introduce dma_get_seg_boundary_nr_pages()
Message-Id: <20200903161252.GA24841@lst.de>
List-Id: <linux-ia64.vger.kernel.org>
References: <20200901221646.26491-1-nicoleotsuka@gmail.com> <20200901221646.26491-2-nicoleotsuka@gmail.com> <CAHp75VcVJBSnPQ6NfdF8FdEDfM+oQ=Sr+cH5VGX4SrAqrgpf-g@mail.gmail.com>
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To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Nicolin Chen <nicoleotsuka@gmail.com>, Christoph Hellwig <hch@lst.de>, Stephen Rothwell <sfr@canb.auug.org.au>, Michael Ellerman <mpe@ellerman.id.au>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, "open list:LINUX FOR POWERPC PA SEMI PWRFICIENT" <linuxppc-dev@lists.ozlabs.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, rth@twiddle.net, ink@jurassic.park.msu.ru, Matt Turner <mattst88@gmail.com>, linux-alpha@vger.kernel.org, Tony Luck <tony.luck@intel.com>, Fenghua Yu <fenghua.yu@intel.com>, linux-ia64@vger.kernel.org, schnelle@linux.ibm.com, gerald.schaefer@linux.ibm.com, hca@linux.ibm.com, Vasily Gorbik <gor@linux.ibm.com>, Christian Borntraeger <borntraeger@de.ibm.com>, linux-s390@vger.kernel.org, "David S. Miller" <davem@davemloft.net>, sparclinux@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>, James Bottomley <James.Bottomley@hansenpartnership.com>, Helge Deller <deller@gmx.de>, linux-parisc@vger.kernel.org

On Thu, Sep 03, 2020 at 01:57:39PM +0300, Andy Shevchenko wrote:
> > +{
> > +       if (!dev)
> > +               return (U32_MAX >> page_shift) + 1;
> > +       return (dma_get_seg_boundary(dev) >> page_shift) + 1;
> 
> Can it be better to do something like
>   unsigned long boundary = dev ? dma_get_seg_boundary(dev) : U32_MAX;
> 
>   return (boundary >> page_shift) + 1;
> 
> ?

I don't really see what that would buy us.