From: Tomasz Figa <tfiga@chromium.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
Hans Verkuil <hverkuil-cisco@xs4all.nl>,
Ricardo Ribalda <ribalda@chromium.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCHv2 8/8] videobuf2: handle non-contiguous DMA allocations
Date: Thu, 17 Jun 2021 18:40:58 +0900 [thread overview]
Message-ID: <CAAFQd5DqK2gSTGjfo-vahXwMzzO9gv26cY=vV6urn3viDLPE7g@mail.gmail.com> (raw)
In-Reply-To: <20210617085233.GA4702@lst.de>
On Thu, Jun 17, 2021 at 5:52 PM Christoph Hellwig <hch@lst.de> wrote:
>
> On Thu, Jun 17, 2021 at 05:30:11PM +0900, Tomasz Figa wrote:
> > We still have use cases for dma_alloc_coherent() and DMA_ATTR_NO_KERNEL_MAPPING.
>
> dma_alloc_coherent does not take a flags argument, so you can't use
> DMA_ATTR_NO_KERNEL_MAPPING with it. What would your use case be here
> anyway? In general DMA_ATTR_NO_KERNEL_MAPPING is rather misnamed, as
> usually there is a kernel mapping, just not one that is coherent and
> should be used.
Sorry, I meant dma_alloc_attrs() and yes, it's indeed a misnomer. Our
use case basically has no need for the additional coherent mapping, so
creation of it can be skipped to save some vmalloc space. (Yes, it
probably only matters for 32-bit architectures.)
next prev parent reply other threads:[~2021-06-17 9:41 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-27 13:13 [PATCHv2 0/8] videobuf2: support new noncontiguous DMA API Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 1/8] videobuf2: rework vb2_mem_ops API Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 2/8] videobuf2: inverse buffer cache_hints flags Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 3/8] videobuf2: split buffer cache_hints initialisation Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 4/8] videobuf2: move cache_hints handling to allocators Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 5/8] videobuf2: add V4L2_MEMORY_FLAG_NON_COHERENT flag Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 6/8] videobuf2: add queue memory coherency parameter Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 7/8] videobuf2: handle V4L2_MEMORY_FLAG_NON_COHERENT flag Sergey Senozhatsky
2021-05-01 3:48 ` Sergey Senozhatsky
2021-06-03 11:32 ` Hans Verkuil
2021-06-17 1:46 ` Sergey Senozhatsky
2021-04-27 13:13 ` [PATCHv2 8/8] videobuf2: handle non-contiguous DMA allocations Sergey Senozhatsky
2021-04-28 6:14 ` Christoph Hellwig
2021-06-03 11:59 ` Hans Verkuil
2021-06-17 7:56 ` Sergey Senozhatsky
2021-06-17 8:01 ` Christoph Hellwig
2021-06-17 8:30 ` Tomasz Figa
2021-06-17 8:52 ` Christoph Hellwig
2021-06-17 9:40 ` Tomasz Figa [this message]
2021-06-17 10:06 ` Christoph Hellwig
2021-06-18 3:21 ` Tomasz Figa
2021-06-18 4:25 ` Christoph Hellwig
2021-06-18 4:44 ` Tomasz Figa
2021-06-22 7:33 ` Christoph Hellwig
2021-07-07 12:42 ` Tomasz Figa
2021-06-25 3:10 ` Sergey Senozhatsky
2021-07-07 12:48 ` Tomasz Figa
2021-07-07 13:29 ` Sergey Senozhatsky
2021-07-07 14:10 ` Tomasz Figa
2021-07-09 7:20 ` Sergey Senozhatsky
2021-06-17 7:56 ` Sergey Senozhatsky
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