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From: Christoph Hellwig <hch@lst.de>
To: Tomasz Figa <tfiga@chromium.org>
Cc: Christoph Hellwig <hch@lst.de>,
	Sergey Senozhatsky <senozhatsky@chromium.org>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	"open list:IOMMU DRIVERS" <iommu@lists.linux-foundation.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Media Mailing List <linux-media@vger.kernel.org>
Subject: Re: [PATCH 8/8] WIP: add a dma_alloc_contiguous API
Date: Wed, 7 Oct 2020 14:24:18 +0200	[thread overview]
Message-ID: <20201007122418.GA31318@lst.de> (raw)
In-Reply-To: <CAAFQd5AtN-ykAF_2mAqGxVugeEegYxfYdS6gD4O3zCY1jznNYA@mail.gmail.com>

On Wed, Oct 07, 2020 at 02:21:43PM +0200, Tomasz Figa wrote:
> My initial feeling is that it should work, but we'll give you a
> definitive answer once we prototype it. :)
> 
> We might actually give it a try in the USB HCD subsystem as well, to
> implement usb_alloc_noncoherent(), as an optimization for drivers
> which have to perform multiple random accesses to the URB buffers. I
> think you might recall discussing this by the way of the pwc and
> uvcvideo camera drivers.

Yes.  I guess for usb the dma_alloc_noncoherent as-is in linux-next
might be better.   So if you have the cycles please prototype it
either way, although for that we'd also need at least a
mmap_noncoherent method, and probaby a get_sgtable_noncoherent one.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Tomasz Figa <tfiga@chromium.org>
Cc: 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>,
	Sergey Senozhatsky <senozhatsky@chromium.org>,
	"open list:IOMMU DRIVERS" <iommu@lists.linux-foundation.org>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH 8/8] WIP: add a dma_alloc_contiguous API
Date: Wed, 7 Oct 2020 14:24:18 +0200	[thread overview]
Message-ID: <20201007122418.GA31318@lst.de> (raw)
In-Reply-To: <CAAFQd5AtN-ykAF_2mAqGxVugeEegYxfYdS6gD4O3zCY1jznNYA@mail.gmail.com>

On Wed, Oct 07, 2020 at 02:21:43PM +0200, Tomasz Figa wrote:
> My initial feeling is that it should work, but we'll give you a
> definitive answer once we prototype it. :)
> 
> We might actually give it a try in the USB HCD subsystem as well, to
> implement usb_alloc_noncoherent(), as an optimization for drivers
> which have to perform multiple random accesses to the URB buffers. I
> think you might recall discussing this by the way of the pwc and
> uvcvideo camera drivers.

Yes.  I guess for usb the dma_alloc_noncoherent as-is in linux-next
might be better.   So if you have the cycles please prototype it
either way, although for that we'd also need at least a
mmap_noncoherent method, and probaby a get_sgtable_noncoherent one.
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply	other threads:[~2020-10-07 12:24 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-30 16:09 dma_alloc_pages / dma_alloc_noncoherent fixups Christoph Hellwig
2020-09-30 16:09 ` Christoph Hellwig
2020-09-30 16:09 ` [PATCH 1/8] dma-mapping: remove the {alloc,free}_noncoherent methods Christoph Hellwig
2020-09-30 16:09   ` Christoph Hellwig
2020-09-30 16:09 ` [PATCH 2/8] dma-mapping: document dma_{alloc,free}_pages Christoph Hellwig
2020-09-30 16:09   ` Christoph Hellwig
2020-09-30 16:09 ` [PATCH 3/8] dma-direct check for highmem pages in dma_direct_alloc_pages Christoph Hellwig
2020-09-30 16:09   ` Christoph Hellwig
2020-09-30 16:09 ` [PATCH 4/8] dma-direct: use __GFP_ZERO " Christoph Hellwig
2020-09-30 16:09   ` Christoph Hellwig
2020-10-06  7:24   ` Hillf Danton
2020-09-30 16:09 ` [PATCH 5/8] dma-direct: factor out a dma_direct_alloc_from_pool helper Christoph Hellwig
2020-09-30 16:09   ` Christoph Hellwig
2020-09-30 16:09 ` [PATCH 6/8] dma-direct: simplify the DMA_ATTR_NO_KERNEL_MAPPING handling Christoph Hellwig
2020-09-30 16:09   ` Christoph Hellwig
2020-09-30 16:09 ` [PATCH 7/8] dma-iommu: remove __iommu_dma_mmap Christoph Hellwig
2020-09-30 16:09   ` Christoph Hellwig
2020-09-30 16:09 ` [PATCH 8/8] WIP: add a dma_alloc_contiguous API Christoph Hellwig
2020-09-30 16:09   ` Christoph Hellwig
2020-10-02 17:50   ` Tomasz Figa
2020-10-02 17:50     ` Tomasz Figa
2020-10-05  8:26     ` Christoph Hellwig
2020-10-05  8:26       ` Christoph Hellwig
2020-10-06 20:56       ` Tomasz Figa
2020-10-06 20:56         ` Tomasz Figa
2020-10-07  6:21         ` Christoph Hellwig
2020-10-07  6:21           ` Christoph Hellwig
2020-10-07 12:21           ` Tomasz Figa
2020-10-07 12:21             ` Tomasz Figa
2020-10-07 12:24             ` Christoph Hellwig [this message]
2020-10-07 12:24               ` Christoph Hellwig
2020-10-14 13:20   ` Tomasz Figa
2020-10-14 13:20     ` Tomasz Figa
2020-10-14 15:03     ` David Laight
2020-10-14 15:03       ` David Laight
2020-11-09 14:53     ` Ricardo Ribalda
2020-11-09 14:53       ` Ricardo Ribalda
2020-11-10  9:25       ` Christoph Hellwig
2020-11-10  9:25         ` Christoph Hellwig
2020-11-10  9:33         ` Ricardo Ribalda
2020-11-10  9:33           ` Ricardo Ribalda
2020-11-10  9:41           ` Christoph Hellwig
2020-11-10  9:41             ` Christoph Hellwig
2020-11-10  9:50           ` Tomasz Figa
2020-11-10  9:50             ` Tomasz Figa
2020-11-10  9:57             ` Christoph Hellwig
2020-11-10  9:57               ` Christoph Hellwig
2020-11-17 21:21               ` Ricardo Ribalda
2020-11-17 21:21                 ` Ricardo Ribalda
2020-11-18 14:25   ` [PATCH] WIP! media: uvcvideo: Use dma_alloc_noncontiguos API Ricardo Ribalda
2020-11-18 14:25     ` Ricardo Ribalda
2020-11-24 11:35     ` Christoph Hellwig
2020-11-24 11:35       ` Christoph Hellwig
2020-11-24 12:01       ` Ricardo Ribalda
2020-11-24 12:01         ` Ricardo Ribalda
2020-11-24 13:33         ` Christoph Hellwig
2020-11-24 13:33           ` Christoph Hellwig

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