From: Christoph Hellwig <hch@lst.de>
To: Nikita Yushchenko <nikita.yoush@cogentembedded.com>
Cc: Will Deacon <will.deacon@arm.com>, Arnd Bergmann <arnd@arndb.de>,
linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
Simon Horman <horms@verge.net.au>,
Bjorn Helgaas <bhelgaas@google.com>,
artemi.ivanov@cogentembedded.com, robin.murphy@arm.com,
fkan@apm.com, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v2] arm64: do not set dma masks that device connection can't handle
Date: Tue, 10 Jan 2017 15:51:06 +0100 [thread overview]
Message-ID: <20170110145106.GC27156@lst.de> (raw)
In-Reply-To: <07253eaa-5729-0f15-42b6-e8403f1f0412@cogentembedded.com>
On Tue, Jan 10, 2017 at 03:47:25PM +0300, Nikita Yushchenko wrote:
> With this direction, semantics of dma mask becomes even more
> questionable. I'd say dma_mask is candidate for removal (or to move to
> swiotlb's or iommu's local area)
We need the dma mask so that the device can advertise what addresses
the device supports. Many old devices only support 32-bit DMA addressing,
and some less common ones just 24-bit or other weird ones.
prev parent reply other threads:[~2017-01-10 14:51 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-09 7:30 [PATCH v2] arm64: do not set dma masks that device connection can't handle Nikita Yushchenko
2017-01-10 11:51 ` Will Deacon
2017-01-10 12:47 ` Nikita Yushchenko
2017-01-10 13:12 ` Arnd Bergmann
2017-01-10 13:25 ` Robin Murphy
2017-01-10 13:42 ` Arnd Bergmann
2017-01-10 14:16 ` Robin Murphy
2017-01-10 15:06 ` Arnd Bergmann
2017-01-11 12:37 ` Nikita Yushchenko
2017-01-11 16:21 ` Arnd Bergmann
2017-01-11 18:28 ` Robin Murphy
2017-01-10 14:59 ` Christoph Hellwig
2017-01-10 14:01 ` Nikita Yushchenko
2017-01-10 14:57 ` Christoph Hellwig
2017-01-10 14:51 ` Christoph Hellwig [this message]
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