From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-mips@linux-mips.org, linux-samsung-soc@vger.kernel.org,
linux-ia64@vger.kernel.org, linux-c6x-dev@linux-c6x.org,
linux-s390@vger.kernel.org, linux-sh@vger.kernel.org,
linux-hexagon@vger.kernel.org, linux-xtensa@linux-xtensa.org,
x86@kernel.org, linux-tegra@vger.kernel.org,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
dmaengine@vger.kernel.org, iommu@lists.linux-foundation.org,
openrisc@lists.librecores.org, netdev@vger.kernel.org,
sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org,
linuxppc-dev@lists.ozlabs.org, Christoph Hellwig <hch@lst.de>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 42/44] powerpc/cell: use the dma_supported method for ops switching
Date: Sun, 18 Jun 2017 19:54:02 +1000 [thread overview]
Message-ID: <1497779642.31581.6.camel__35655.2925114103$1497779841$gmane$org@kernel.crashing.org> (raw)
In-Reply-To: <20170618071344.GB18526@infradead.org>
On Sun, 2017-06-18 at 00:13 -0700, Christoph Hellwig wrote:
> On Sun, Jun 18, 2017 at 06:50:27AM +1000, Benjamin Herrenschmidt wrote:
> > What is your rationale here ? (I have missed patch 0 it seems).
>
> Less code duplication, more modular dma_map_ops insteance.
>
> > dma_supported() was supposed to be pretty much a "const" function
> > simply informing whether a given setup is possible. Having it perform
> > an actual switch of ops seems to be pushing it...
>
> dma_supported() is already gone from the public DMA API as it doesn't
> make sense to be called separately from set_dma_mask. It will be
> entirely gone in the next series after this one.
Ah ok, in that case it makes much more sense, we can rename it then.
> > What if a driver wants to test various dma masks and then pick one ?
> >
> > Where does the API documents that if a driver calls dma_supported() it
> > then *must* set the corresponding mask and use that ?
>
> Where is the API document for _any_ of the dma routines? (A: work in
> progress by me, but I need to clean up the mess of arch hooks before
> it can make any sense)
Heh fair enough.
> > I don't like a function that is a "boolean query" like this one to have
> > such a major side effect.
> >
> > > From an API standpoint, dma_set_mask() is when the mask is established,
> >
> > and thus when the ops switch should happen.
>
> And that's exactly what happens at the driver API level. It just turns
> out the dma_capable method is they way better place to actually
> implement it, as the ->set_dma_mask method requires lots of code
> duplication while not offering any actual benefit over ->dma_capable.
> And because of that it's gone after this series.
>
> In theory we could rename ->dma_capable now, but it would require a
> _lot_ of churn. Give me another merge window or two and we should
> be down to be about 2 handful of dma_map_ops instance, at which point
> we could do all this gratious renaming a lot more easily :)
Sure, I get it now, as long as it's not publicly exposed to drivers
we are fine.
Cheers,
Ben.
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next prev parent reply other threads:[~2017-06-18 9:55 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20170616181059.19206-1-hch@lst.de>
2017-06-16 18:10 ` [PATCH 01/44] firmware/ivc: use dma_mapping_error Christoph Hellwig
2017-06-16 18:10 ` [PATCH 02/44] ibmveth: properly unwind on init errors Christoph Hellwig
2017-06-16 18:10 ` [PATCH 03/44] dmaengine: ioat: don't use DMA_ERROR_CODE Christoph Hellwig
2017-06-16 18:10 ` [PATCH 04/44] drm/exynos: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 05/44] drm/armada: don't abuse DMA_ERROR_CODE Christoph Hellwig
2017-06-16 18:10 ` [PATCH 06/44] iommu/dma: don't rely on DMA_ERROR_CODE Christoph Hellwig
2017-06-16 18:10 ` [PATCH 07/44] xen-swiotlb: consolidate xen_swiotlb_dma_ops Christoph Hellwig
2017-06-16 18:10 ` [PATCH 08/44] xen-swiotlb: implement ->mapping_error Christoph Hellwig
2017-06-16 18:10 ` [PATCH 09/44] c6x: remove DMA_ERROR_CODE Christoph Hellwig
2017-06-16 18:10 ` [PATCH 10/44] ia64: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 11/44] m32r: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 12/44] microblaze: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 13/44] openrisc: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 14/44] sh: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 15/44] xtensa: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 16/44] arm64: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 17/44] hexagon: switch to use ->mapping_error for error reporting Christoph Hellwig
2017-06-16 18:10 ` [PATCH 18/44] iommu/amd: implement ->mapping_error Christoph Hellwig
2017-06-16 18:10 ` [PATCH 19/44] s390: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 20/44] sparc: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 21/44] powerpc: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 22/44] x86/pci-nommu: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 23/44] x86/calgary: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 24/44] x86: remove DMA_ERROR_CODE Christoph Hellwig
2017-06-16 18:10 ` [PATCH 25/44] arm: implement ->mapping_error Christoph Hellwig
2017-06-16 18:10 ` [PATCH 26/44] dma-mapping: remove DMA_ERROR_CODE Christoph Hellwig
2017-06-16 18:10 ` [PATCH 27/44] sparc: remove leon_dma_ops Christoph Hellwig
2017-06-16 18:10 ` [PATCH 28/44] sparc: remove arch specific dma_supported implementations Christoph Hellwig
2017-06-16 18:10 ` [PATCH 29/44] dma-noop: remove dma_supported and mapping_error methods Christoph Hellwig
2017-06-16 18:10 ` [PATCH 30/44] dma-virt: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 31/44] hexagon: remove arch-specific dma_supported implementation Christoph Hellwig
2017-06-16 18:10 ` [PATCH 32/44] hexagon: remove the unused dma_is_consistent prototype Christoph Hellwig
2017-06-16 18:10 ` [PATCH 33/44] openrisc: remove arch-specific dma_supported implementation Christoph Hellwig
2017-06-16 18:10 ` [PATCH 34/44] arm: remove arch specific " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 35/44] x86: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 36/44] dma-mapping: remove HAVE_ARCH_DMA_SUPPORTED Christoph Hellwig
2017-06-16 18:10 ` [PATCH 37/44] mips/loongson64: implement ->dma_supported instead of ->set_dma_mask Christoph Hellwig
2017-06-16 18:10 ` [PATCH 38/44] arm: " Christoph Hellwig
2017-06-16 18:10 ` [PATCH 39/44] xen-swiotlb: remove xen_swiotlb_set_dma_mask Christoph Hellwig
2017-06-16 18:10 ` [PATCH 40/44] tile: remove dma_supported and mapping_error methods Christoph Hellwig
2017-06-16 18:10 ` [PATCH 41/44] powerpc/cell: clean up fixed mapping dma_ops initialization Christoph Hellwig
2017-06-16 18:10 ` [PATCH 42/44] powerpc/cell: use the dma_supported method for ops switching Christoph Hellwig
2017-06-16 18:10 ` [PATCH 43/44] dma-mapping: remove the set_dma_mask method Christoph Hellwig
2017-06-16 18:10 ` [PATCH 44/44] powerpc: merge __dma_set_mask into dma_set_mask Christoph Hellwig
[not found] ` <20170616181059.19206-4-hch@lst.de>
2017-06-16 20:40 ` [PATCH 03/44] dmaengine: ioat: don't use DMA_ERROR_CODE Alexander Duyck
[not found] ` <CAKgT0UdxrimWrxNVsLMQ9G6ABBJZwfWHTcP18qqd4rT0Fa-KWg@mail.gmail.com>
2017-06-18 7:09 ` Christoph Hellwig
[not found] ` <20170616181059.19206-43-hch@lst.de>
2017-06-17 20:50 ` [PATCH 42/44] powerpc/cell: use the dma_supported method for ops switching Benjamin Herrenschmidt
[not found] ` <1497732627.2897.128.camel@kernel.crashing.org>
2017-06-18 7:13 ` Christoph Hellwig
[not found] ` <20170618071344.GB18526@infradead.org>
2017-06-18 9:54 ` Benjamin Herrenschmidt [this message]
[not found] ` <20170616181059.19206-7-hch@lst.de>
2017-06-19 15:12 ` [PATCH 06/44] iommu/dma: don't rely on DMA_ERROR_CODE Robin Murphy
2017-06-20 12:41 ` new dma-mapping tree, was Re: clean up and modularize arch dma_mapping interface V2 Christoph Hellwig
[not found] ` <20170620124140.GA27163@lst.de>
2017-06-20 13:04 ` Stephen Rothwell
2017-06-20 13:14 ` Robin Murphy
[not found] ` <6025d4d4-1975-9598-c16d-26d17d029ec7@arm.com>
2017-06-20 13:15 ` Christoph Hellwig
[not found] ` <20170620230400.1a5ae889@canb.auug.org.au>
2017-06-20 13:16 ` Christoph Hellwig
[not found] ` <CGME20170620131628epcas1p4f21d821bd414cba7e2d49abcbe414365@epcas1p4.samsung.com>
[not found] ` <20170620131623.GB30769@lst.de>
2017-06-21 13:32 ` Marek Szyprowski
[not found] ` <5425587c-73e8-e24a-86a3-8a65a7791dcb@samsung.com>
2017-06-22 21:53 ` Stephen Rothwell
2017-06-26 7:03 ` Christoph Hellwig
2017-06-21 19:24 ` tndave
[not found] ` <162d7932-5766-4c29-5471-07d1b699190a@oracle.com>
2017-06-24 7:18 ` Christoph Hellwig
[not found] ` <20170624071855.GD14580@lst.de>
2017-06-24 15:36 ` Benjamin Herrenschmidt
[not found] ` <1498318616.31581.87.camel@kernel.crashing.org>
2017-06-26 9:47 ` Christoph Hellwig
[not found] ` <20170626094739.GB13981@lst.de>
2017-06-26 22:06 ` tndave
[not found] <20170608132609.32662-1-hch@lst.de>
2017-06-08 13:26 ` [PATCH 42/44] powerpc/cell: use the dma_supported method for ops switching Christoph Hellwig
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