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From: Christoph Hellwig <hch@lst.de>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Christoph Hellwig <hch@lst.de>,
	linux-arch@vger.kernel.org, Michal Simek <monstr@monstr.eu>,
	Greentime Hu <green.hu@gmail.com>,
	Vincent Chen <deanbo422@gmail.com>,
	linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org,
	linux-c6x-dev@linux-c6x.org, linux-hexagon@vger.kernel.org,
	linux-m68k@vger.kernel.org, nios2-dev@lists.rocketboards.org,
	openrisc@lists.librecores.org, linux-parisc@vger.kernel.org,
	linux-sh@vger.kernel.org, sparclinux@vger.kernel.org,
	linux-xtensa@linux-xtensa.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 22/22] parisc: use generic dma_noncoherent_ops
Date: Tue, 24 Apr 2018 10:20:23 +0200	[thread overview]
Message-ID: <20180424082023.GA19725@lst.de> (raw)
In-Reply-To: <1524346967.3335.9.camel@HansenPartnership.com>

On Sat, Apr 21, 2018 at 10:42:47PM +0100, James Bottomley wrote:
> Well, this is wrong: you just made every 32 bit parisc system
> unnecessarily use non-coherent.  We actually only have a small small
> set of non-coherent systems.  The pxcs and pcxt systems (which are
> about 99% of the user base) can use coherent dma ops.  The problem
> seems to be in your new world you only have one dma_noncoherent_ops
> pointer ... we definitely need two on parisc, so whether
> arch_dma_cache_sync is present or not needs to be dynamic not config
> defined.

The changelog explicitly mentions merging the two noncoherent
implementations, they only differ in the alloc and free callsbacks,
and we now runtime switch between them.  Before the pcxs and pcxt
cases used pcx_dma_ops, and pcxl and pxcl2 used pcxl_dma_ops, now
all four use dma_noncoherent_ops and arch_dma_alloc/arch_dma_free
branch out to different behavior.

Both pcx_dma_ops and pcxl_dma_ops do define the cache_sync
method in the existing code, so that isn't the issue.

I'll take a deeper look at what sort of behavior change might have
been introduced.

> 
> James
---end quoted text---

      reply	other threads:[~2018-04-24  8:19 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-20  8:02 Christoph Hellwig
2018-04-20  8:02 ` [PATCH 01/22] dma-debug: move initialization to common code Christoph Hellwig
2018-04-20 10:23   ` Robin Murphy
2018-04-24  7:35     ` Christoph Hellwig
2018-04-20  8:02 ` [PATCH 02/22] dma-mapping: simplify Kconfig dependencies Christoph Hellwig
2018-04-20  8:02 ` [PATCH 03/22] dma-mapping: provide a generic dma-noncoherent implementation Christoph Hellwig
2018-04-20  8:02 ` [PATCH 04/22] alpha: use dma_direct_ops for jensen Christoph Hellwig
2018-04-20  8:02 ` [PATCH 05/22] alpha: simplify get_arch_dma_ops Christoph Hellwig
2018-04-20  8:02 ` [PATCH 06/22] arc: use generic dma_noncoherent_ops Christoph Hellwig
2018-04-25 11:17   ` Alexey Brodkin
2018-04-26  6:45     ` hch
2018-04-26  8:25       ` hch
2018-04-20  8:02 ` [PATCH 07/22] arm-nommu: " Christoph Hellwig
2018-04-20  8:02 ` [PATCH 08/22] c6x: " Christoph Hellwig
2018-04-20  8:03 ` [PATCH 09/22] hexagon: " Christoph Hellwig
2018-04-20  8:03 ` [PATCH 10/22] m68k: " Christoph Hellwig
2018-04-20  8:03 ` [PATCH 11/22] microblaze: " Christoph Hellwig
2018-04-20  8:03 ` [PATCH 12/22] microblaze: remove the consistent_sync and consistent_sync_page Christoph Hellwig
2018-04-20  8:03 ` [PATCH 13/22] nds32: use generic dma_noncoherent_ops Christoph Hellwig
2018-04-23  6:49   ` Greentime Hu
2018-04-24 19:16     ` Christoph Hellwig
2018-04-25  1:43       ` Greentime Hu
2018-04-25  6:40         ` Christoph Hellwig
2018-04-25 12:25           ` Greentime Hu
2018-04-26  6:42             ` Christoph Hellwig
2018-04-26  8:06               ` Greentime Hu
2018-04-26  8:24                 ` Christoph Hellwig
2018-04-26  9:39                   ` Greentime Hu
2018-04-20  8:03 ` [PATCH 14/22] nios2: " Christoph Hellwig
2018-04-20  8:03 ` [PATCH 15/22] openrisc: " Christoph Hellwig
2018-04-20  8:03 ` [PATCH 16/22] sh: simplify get_arch_dma_ops Christoph Hellwig
2018-04-20  8:03 ` [PATCH 17/22] sh: introduce a sh_cacheop_vaddr helper Christoph Hellwig
2018-04-20  8:03 ` [PATCH 18/22] sh: use dma_direct_ops for the CONFIG_DMA_COHERENT case Christoph Hellwig
2018-04-20  8:03 ` [PATCH 19/22] sh: use generic dma_noncoherent_ops Christoph Hellwig
2018-04-20  8:03 ` [PATCH 20/22] xtensa: " Christoph Hellwig
2018-04-20  8:03 ` [PATCH 21/22] sparc: " Christoph Hellwig
2018-04-20  8:03 ` [PATCH 22/22] parisc: " Christoph Hellwig
2018-04-21 17:43   ` Helge Deller
2018-04-21 21:52     ` James Bottomley
2018-04-25  7:21     ` Christoph Hellwig
2018-04-25 21:07       ` Helge Deller
2018-04-21 21:42   ` James Bottomley
2018-04-24  8:20     ` Christoph Hellwig [this message]

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