From: ". Christoph Hellwig" <hch@lst.de>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Sergey Senozhatsky <senozhatsky@google.com>,
Linux Media Mailing List <linux-media@vger.kernel.org>,
Linux Doc Mailing List <linux-doc@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
IOMMU DRIVERS <iommu@lists.linux-foundation.org>,
Ricardo Ribalda <ribalda@chromium.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Robin Murphy <robin.murphy@arm.com>,
". Christoph Hellwig" <hch@lst.de>
Subject: Re: [PATCH v3 5/6] media: uvcvideo: Use dma_alloc_noncontiguos API
Date: Wed, 9 Dec 2020 12:16:39 +0100 [thread overview]
Message-ID: <20201209111639.GB22806@lst.de> (raw)
In-Reply-To: <20201208071320.GA1667627@google.com>
On Tue, Dec 08, 2020 at 04:13:20PM +0900, Sergey Senozhatsky wrote:
> On (20/12/08 13:54), Tomasz Figa wrote:
> >
> > In any case, Sergey is going to share a preliminary patch on how the
> > current API would be used in the V4L2 videobuf2 framework. That should
> > give us more input on how such a helper could look.
>
> HUGE apologies for the previous screw up! I replied in the
> gmail web-interface and that did not work out as expected
> (at all, big times).
Actually the previous mail was a mime multipart one, and the plain text
version displayed just fine here. My the gmail engineers finally learned
something after all.
> Another thing to notice is that the new API requires us to have two execution branches
> in allocators - one for the current API; and one for the new API (if it's supported and
> if user-space requested non-coherent allocation).
So I think we do want these branches for coherent vs non-coherent as they
have very different semantics and I do not think that hiding them under
the same API helps people to understand those vastly different semantics.
OTOH we should look into a fallback for DMA API instances that do not
support the discontigous allocations.
I think between your comments and those from Ricardo I have a good idea
for a somewhat updated API. I'll try to post something in the next days.
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next prev parent reply other threads:[~2020-12-09 11:16 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-25 22:19 [PATCH v3 5/6] media: uvcvideo: Use dma_alloc_noncontiguos API Ricardo Ribalda
2020-11-26 11:44 ` Sergey Senozhatsky
2020-11-30 8:31 ` Christoph Hellwig
2020-11-30 8:34 ` Christoph Hellwig
2020-11-30 10:49 ` Ricardo Ribalda
2020-12-01 3:36 ` Sergey Senozhatsky
2020-12-01 14:49 ` Christoph Hellwig
2020-12-08 4:54 ` Tomasz Figa
2020-12-08 6:45 ` Sergey Senozhatsky via iommu
2020-12-08 7:13 ` Sergey Senozhatsky
2020-12-09 11:16 ` . Christoph Hellwig [this message]
2021-01-07 14:14 ` Ricardo Ribalda
2021-01-11 8:36 ` . Christoph Hellwig
2021-01-15 13:08 ` Ricardo Ribalda
2021-01-20 17:17 ` . Christoph Hellwig
2021-01-26 17:06 ` . Christoph Hellwig
2021-01-26 23:29 ` Ricardo Ribalda
2021-01-27 15:56 ` . Christoph Hellwig
2021-01-27 21:35 ` Ricardo Ribalda
2021-01-28 7:57 ` . Christoph Hellwig
2020-12-09 11:12 ` Christoph Hellwig
2020-12-09 13:05 ` Robin Murphy
2020-12-10 5:08 ` Tomasz Figa
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