linux-kernel - Re: remove the ->mapping_error method from dma_map

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Date:   Thu, 22 Nov 2018 17:14:47 +0000
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Christoph Hellwig <hch@....de>, linux-arch@...r.kernel.org,
        linux-alpha@...r.kernel.org, linux-ia64@...r.kernel.org,
        linux-parisc@...r.kernel.org,
        David Woodhouse <dwmw2@...radead.org>, joro@...tes.org,
        the arch/x86 maintainers <x86@...nel.org>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        iommu@...ts.linux-foundation.org, jdmason@...zu.us,
        xen-devel@...ts.xenproject.org, robin.murphy@....com,
        linux-arm-kernel@...ts.infradead.org, m.szyprowski@...sung.com
Subject: Re: remove the ->mapping_error method from dma_map_ops V2

On Thu, Nov 22, 2018 at 09:09:47AM -0800, Linus Torvalds wrote:
> On Thu, Nov 22, 2018 at 9:07 AM Russell King - ARM Linux
> <linux@...linux.org.uk> wrote:
> >
> > I'm afraid that won't work very well - 32 bit platforms with 64-bit
> > addresses (LPAE) would have dma_addr_t as a 64-bit value, which
> > wouldn't fit into an unsigned long.
> 
> Good point. So we'd have to have a special IS_DMA_ERR() function that
> takes a dma_addr_t and checks the same "is it the top 4095 values".

No problem with that.

-- 
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