From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: Christoph Hellwig <hch@lst.de>, Will Deacon <will.deacon@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
linux-arm-kernel@lists.infradead.org,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 09/10] swiotlb: add support for non-coherent DMA
Date: Fri, 26 Oct 2018 10:04:21 +0200 [thread overview]
Message-ID: <20181026080421.GA6100@lst.de> (raw)
In-Reply-To: <9ea28547-dd1a-b4bd-2e91-f71e70417e7d@arm.com>
On Mon, Oct 22, 2018 at 06:11:04PM +0100, Robin Murphy wrote:
>> + if (!dev_is_dma_coherent(dev) &&
>> + (attrs & DMA_ATTR_SKIP_CPU_SYNC) == 0)
>
> Nit: other parts of the file are already using the "!(...)" style rather
> than "(...) == 0".
Indeed. Probably some kind of copy and past error..
> I had a quick play at moving the cache maintenance here out into the
> callers, which comes out arguably looking perhaps a little cleaner (only +1
> source line overall, and actually reduces text size by 32 bytes for my
> build), but sadly I can't really see any way of doing the equivalent for
> map/unmap short of duplicating the whole 3-line arch_sync_*() block, which
> just makes for a different readability problem. As you mentioned on patch
> #7, I guess this really is just one of those things which has no nice
> solution, so cosmetics aside,
It looks pretty ok, but given that I want to send this version to
Linus for the merge window I don't really dare to touch it.
The master plan for 4.21 is to actually merge swiotlb into dma-direct
and to allow direct calls to dma-direct given how expensive indirect
calls are with spectre, and dma mappings show up badly in various
benchmarks. I'll see if I can do that in a way following what you've
done.
next prev parent reply other threads:[~2018-10-26 8:04 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-08 8:02 move swiotlb noncoherent dma support from arm64 to generic code V2 Christoph Hellwig
2018-10-08 8:02 ` [PATCH 01/10] swiotlb: remove a pointless comment Christoph Hellwig
2018-10-11 17:49 ` Robin Murphy
2018-10-19 0:09 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 02/10] swiotlb: mark is_swiotlb_buffer static Christoph Hellwig
2018-10-11 17:54 ` Robin Murphy
2018-10-19 0:12 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 03/10] swiotlb: do not panic on mapping failures Christoph Hellwig
2018-10-11 18:06 ` Robin Murphy
2018-10-19 0:18 ` Konrad Rzeszutek Wilk
2018-10-19 0:17 ` Konrad Rzeszutek Wilk
2018-10-19 6:04 ` Christoph Hellwig
2018-10-19 13:45 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 04/10] swiotlb: remove the overflow buffer Christoph Hellwig
2018-10-11 18:19 ` Robin Murphy
2018-10-12 17:04 ` Catalin Marinas
2018-10-19 0:23 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 05/10] swiotlb: merge swiotlb_unmap_page and unmap_single Christoph Hellwig
2018-10-18 17:44 ` Robin Murphy
2018-10-19 0:25 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 06/10] swiotlb: use swiotlb_map_page in swiotlb_map_sg_attrs Christoph Hellwig
2018-10-18 17:53 ` Robin Murphy
2018-10-19 0:33 ` Konrad Rzeszutek Wilk
2018-11-07 1:27 ` John Stultz
2018-11-09 7:49 ` Christoph Hellwig
2018-11-09 16:37 ` Robin Murphy
2018-11-19 19:36 ` Robin Murphy
2018-11-20 9:22 ` Christoph Hellwig
2018-11-13 0:07 ` John Stultz
2018-11-13 0:26 ` John Stultz
2018-11-14 14:13 ` Christoph Hellwig
2018-11-14 16:12 ` Christoph Hellwig
2018-11-19 23:22 ` John Stultz
2018-11-20 9:25 ` Christoph Hellwig
2018-11-23 18:27 ` Will Deacon
2018-11-23 19:34 ` Robin Murphy
2018-11-26 19:31 ` Will Deacon
2018-10-08 8:02 ` [PATCH 07/10] swiotlb: refactor swiotlb_map_page Christoph Hellwig
2018-10-18 18:09 ` Robin Murphy
2018-10-19 0:37 ` Konrad Rzeszutek Wilk
2018-10-19 6:52 ` Christoph Hellwig
2018-10-19 13:46 ` Konrad Rzeszutek Wilk
2018-10-08 8:02 ` [PATCH 08/10] swiotlb: don't dip into swiotlb pool for coherent allocations Christoph Hellwig
2018-10-12 17:04 ` Catalin Marinas
2018-10-19 0:40 ` Konrad Rzeszutek Wilk
2018-10-19 16:45 ` Robin Murphy
2018-10-08 8:02 ` [PATCH 09/10] swiotlb: add support for non-coherent DMA Christoph Hellwig
2018-10-19 0:49 ` Konrad Rzeszutek Wilk
2018-10-22 17:11 ` Robin Murphy
2018-10-26 8:04 ` Christoph Hellwig [this message]
2018-10-26 9:59 ` Robin Murphy
2018-10-08 8:02 ` [PATCH 10/10] arm64: use the generic swiotlb_dma_ops Christoph Hellwig
2018-10-12 13:01 ` Robin Murphy
2018-10-12 14:40 ` Christoph Hellwig
2018-10-12 17:05 ` Catalin Marinas
2018-10-22 17:52 ` Robin Murphy
2018-10-26 12:44 ` Christoph Hellwig
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