From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Paul Burton <paul.burton@mips.com>,
iommu@lists.linux-foundation.org,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-mips@linux-mips.org, linux-kernel@vger.kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH] MIPS: Fix `dma_alloc_coherent' returning a non-coherent allocation
Date: Thu, 1 Nov 2018 14:30:34 +0000 (GMT) [thread overview]
Message-ID: <alpine.LFD.2.21.1811011405530.20378@eddie.linux-mips.org> (raw)
In-Reply-To: <20181101083346.GA7136@lst.de>
On Thu, 1 Nov 2018, Christoph Hellwig wrote:
> Oops, yes this looks good:
BTW, for anyone missing hardware suitable for serious DMA testing I can
recommend getting a pair of DEFPA cards, the ubiquitous PCI version of
this board, cheaply available, which is the same except for a different
host bus bridge ASIC, developed later. They can be wired back to back
similarly to Ethernet adapters (or in a loop if you have 2 or more dual
attachment versions), no other hardware is required save for patch cords.
Version 3 (DEFPA-xC) boards support universal PCI signalling, older ones
are 5V-only.
These devices are a stellar example of fine engineering[1]. Our `defxx'
driver, which I believe has been adapted from the DEC OSF/1 one referred
in the said document, has some latency and other issues that I plan to
address sometime, once I have sorted higher-priority issues, however
hardware itself is excellent.
References:
[1] Chran-Ham Chang et al., "High-performance TCP/IP and UDP/IP Networking
in DEC OSF/1 for Alpha AXP", Digital Technical Journal, vol. 5, no. 1
(Winter 1993), "Network Adapter Characteristics", p. 7
<ftp://ftp.linux-mips.org/pub/linux/mips/people/macro/DEC/DTJ/DTJ904/DTJ904PF.PDF>
Maciej
next prev parent reply other threads:[~2018-11-01 14:32 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-14 9:58 merge dma_direct_ops and dma_noncoherent_ops v3 Christoph Hellwig
2018-09-14 9:58 ` [PATCH 1/6] dma-mapping: add the missing ARCH_HAS_SYNC_DMA_FOR_CPU_ALL declaration Christoph Hellwig
2018-09-14 9:58 ` [PATCH 2/6] MIPS: don't select DMA_MAYBE_COHERENT from DMA_PERDEV_COHERENT Christoph Hellwig
2018-09-14 9:58 ` [PATCH 3/6] dma-mapping: move the dma_coherent flag to struct device Christoph Hellwig
2018-09-14 9:58 ` [PATCH 4/6] dma-mapping: merge direct and noncoherent ops Christoph Hellwig
2018-10-31 14:24 ` Maciej W. Rozycki
2018-10-31 16:31 ` Maciej W. Rozycki
2018-10-31 20:32 ` Christoph Hellwig
2018-10-31 20:50 ` Maciej W. Rozycki
2018-11-01 5:13 ` Christoph Hellwig
2018-11-01 7:54 ` [PATCH] MIPS: Fix `dma_alloc_coherent' returning a non-coherent allocation Maciej W. Rozycki
2018-11-01 8:33 ` Christoph Hellwig
2018-11-01 14:30 ` Maciej W. Rozycki [this message]
2018-11-05 18:10 ` Paul Burton
2018-09-14 9:58 ` [PATCH 5/6] dma-mapping: consolidate the dma mmap implementations Christoph Hellwig
2018-09-14 9:58 ` [PATCH 6/6] dma-mapping: support non-coherent devices in dma_common_get_sgtable Christoph Hellwig
2018-09-20 7:02 ` merge dma_direct_ops and dma_noncoherent_ops v3 Christoph Hellwig
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