From: Robin Murphy <robin.murphy@arm.com>
To: Christoph Hellwig <hch@lst.de>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
Joonyoung Shim <jy0922.shim@samsung.com>,
Seung-Woo Kim <sw0312.kim@samsung.com>,
Ben Skeggs <bskeggs@redhat.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Tomasz Figa <tfiga@chromium.org>,
Matt Porter <mporter@kernel.crashing.org>,
iommu@lists.linux-foundation.org
Cc: alsa-devel@alsa-project.org, linux-samsung-soc@vger.kernel.org,
linux-scsi@vger.kernel.org, linux-parisc@vger.kernel.org,
linux-doc@vger.kernel.org, nouveau@lists.freedesktop.org,
linux-kernel@vger.kernel.org, linux-mips@vger.kernel.org,
linux-mm@kvack.org, Stefan Richter <stefanr@s5r6.in-berlin.de>,
netdev@vger.kernel.org, linux1394-devel@lists.sourceforge.net,
linux-arm-kernel@lists.infradead.org,
linux-media@vger.kernel.org
Subject: Re: [PATCH 08/18] dma-mapping: add a new dma_alloc_noncoherent API
Date: Fri, 25 Sep 2020 12:15:37 +0100 [thread overview]
Message-ID: <c8ea4023-3e19-d63b-d936-46a04f502a61@arm.com> (raw)
In-Reply-To: <20200915155122.1768241-9-hch@lst.de>
On 2020-09-15 16:51, Christoph Hellwig wrote:
[...]
> +These APIs allow to allocate pages in the kernel direct mapping that are
> +guaranteed to be DMA addressable. This means that unlike dma_alloc_coherent,
> +virt_to_page can be called on the resulting address, and the resulting
Nit: if we explicitly describe this as if it's a guarantee that can be
relied upon...
> +struct page can be used for everything a struct page is suitable for.
[...]
> +This routine allocates a region of <size> bytes of consistent memory. It
> +returns a pointer to the allocated region (in the processor's virtual address
> +space) or NULL if the allocation failed. The returned memory may or may not
> +be in the kernels direct mapping. Drivers must not call virt_to_page on
> +the returned memory region.
...then forbid this document's target audience from relying on it,
something seems off. At the very least it's unhelpfully unclear :/
Given patch #17, I suspect that the first paragraph is the one that's no
longer true.
Robin.
next prev parent reply other threads:[~2020-09-25 11:16 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 15:51 a saner API for allocating DMA addressable pages v3 Christoph Hellwig
2020-09-15 15:51 ` [PATCH 01/18] media/v4l2: remove V4L2-FLAG-MEMORY-NON-CONSISTENT flag Christoph Hellwig
2020-09-25 18:47 ` Tomasz Figa
2020-09-15 15:51 ` [PATCH 02/18] mm: turn alloc_pages into an inline function Christoph Hellwig
2020-09-15 15:51 ` [PATCH 03/18] drm/exynos: stop setting DMA_ATTR_NON_CONSISTENT Christoph Hellwig
2020-09-15 15:51 ` [PATCH 04/18] drm/nouveau/gk20a: " Christoph Hellwig
2020-09-15 15:51 ` [PATCH 05/18] net/au1000-eth: stop using DMA_ATTR_NON_CONSISTENT Christoph Hellwig
2020-09-15 15:51 ` [PATCH 06/18] lib82596: move DMA allocation into the callers of i82596_probe Christoph Hellwig
2020-09-22 8:48 ` Thomas Bogendoerfer
2020-09-15 15:51 ` [PATCH 07/18] 53c700: improve non-coherent DMA handling Christoph Hellwig
2020-09-22 8:49 ` Thomas Bogendoerfer
2020-09-15 15:51 ` [PATCH 08/18] dma-mapping: add a new dma_alloc_noncoherent API Christoph Hellwig
2020-09-25 11:15 ` Robin Murphy [this message]
2020-09-25 16:17 ` Christoph Hellwig
2020-09-15 15:51 ` [PATCH 09/18] sgiwd93: convert to dma_alloc_noncoherent Christoph Hellwig
2020-09-22 8:49 ` Thomas Bogendoerfer
2020-09-15 15:51 ` [PATCH 10/18] hal2: " Christoph Hellwig
2020-09-22 8:50 ` Thomas Bogendoerfer
2020-09-15 15:51 ` [PATCH 11/18] lib82596: " Christoph Hellwig
2020-09-22 8:50 ` Thomas Bogendoerfer
2020-09-15 15:51 ` [PATCH 12/18] sgiseeq: " Christoph Hellwig
2020-09-22 8:51 ` Thomas Bogendoerfer
2020-09-15 15:51 ` [PATCH 13/18] 53c700: " Christoph Hellwig
2020-09-22 8:51 ` Thomas Bogendoerfer
2020-09-15 15:51 ` [PATCH 14/18] dma-mapping: remove dma_cache_sync Christoph Hellwig
2020-09-22 8:52 ` Thomas Bogendoerfer
2020-09-15 15:51 ` [PATCH 15/18] dma-mapping: add a new dma_alloc_pages API Christoph Hellwig
2020-09-22 8:53 ` Thomas Bogendoerfer
2020-09-15 15:51 ` [PATCH 16/18] dma-mapping: add new {alloc, free}_noncoherent dma_map_ops methods Christoph Hellwig
2020-09-15 15:51 ` [PATCH 17/18] dma-iommu: implement ->alloc_noncoherent Christoph Hellwig
2020-09-25 18:46 ` Tomasz Figa
2020-09-26 14:14 ` Christoph Hellwig
2020-09-26 15:25 ` Tomasz Figa
2020-09-15 15:51 ` [PATCH 18/18] firewire-ohci: use dma_alloc_pages Christoph Hellwig
2020-09-21 6:36 ` a saner API for allocating DMA addressable pages v3 Christoph Hellwig
2020-09-25 4:21 ` Christoph Hellwig
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