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From: Vinod Koul <vkoul@kernel.org>
To: Lars-Peter Clausen <lars@metafoo.de>
Cc: Adrian Larumbe <adrian.martinezlarumbe@imgtec.com>,
	dmaengine@vger.kernel.org, michal.simek@xilinx.com,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/4] Expand Xilinx CDMA functions
Date: Fri, 23 Apr 2021 22:50:40 +0530	[thread overview]
Message-ID: <YIMB6DpM//wrPC6q@vkoul-mobl.Dlink> (raw)
In-Reply-To: <bed31611-a084-2a05-f3a3-25585a47be9a@metafoo.de>

On 23-04-21, 15:51, Lars-Peter Clausen wrote:
> On 4/23/21 3:24 PM, Vinod Koul wrote:
> > On 23-04-21, 11:17, Lars-Peter Clausen wrote:
> > > It seems to me what we are missing from the DMAengine API is the equivalent
> > > of device_prep_dma_memcpy() that is able to take SG lists. There is already
> > > a memset_sg, it should be possible to add something similar for memcpy.
> > You mean something like dmaengine_prep_dma_sg() which was removed?
> > 
> Ah, that's why I could have sworn we already had this!

Even at that time we had the premise that we can bring the API back if
we had users. I think many have asked for it, but I havent seen a patch
with user yet :)

> > static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_sg(
> >                 struct dma_chan *chan,
> >                 struct scatterlist *dst_sg, unsigned int dst_nents,
> >                 struct scatterlist *src_sg, unsigned int src_nents,
> >                 unsigned long flags)
> > 
> > The problem with this API is that it would work only when src_sg and
> > dst_sg is of similar nature, if not then how should one go about
> > copying...should we fill without a care for dst_sg being different than
> > src_sg as long as total data to be copied has enough space in dst...
> At least for the CDMA the only requirement is that both buffers have the
> same total size.

I will merge if with a user but semantics need to be absolutely clear on
what is allowed and not, do I hear a volunteer ?
-- 
~Vinod

WARNING: multiple messages have this Message-ID (diff)
From: Vinod Koul <vkoul@kernel.org>
To: Lars-Peter Clausen <lars@metafoo.de>
Cc: Adrian Larumbe <adrian.martinezlarumbe@imgtec.com>,
	dmaengine@vger.kernel.org, michal.simek@xilinx.com,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 0/4] Expand Xilinx CDMA functions
Date: Fri, 23 Apr 2021 22:50:40 +0530	[thread overview]
Message-ID: <YIMB6DpM//wrPC6q@vkoul-mobl.Dlink> (raw)
In-Reply-To: <bed31611-a084-2a05-f3a3-25585a47be9a@metafoo.de>

On 23-04-21, 15:51, Lars-Peter Clausen wrote:
> On 4/23/21 3:24 PM, Vinod Koul wrote:
> > On 23-04-21, 11:17, Lars-Peter Clausen wrote:
> > > It seems to me what we are missing from the DMAengine API is the equivalent
> > > of device_prep_dma_memcpy() that is able to take SG lists. There is already
> > > a memset_sg, it should be possible to add something similar for memcpy.
> > You mean something like dmaengine_prep_dma_sg() which was removed?
> > 
> Ah, that's why I could have sworn we already had this!

Even at that time we had the premise that we can bring the API back if
we had users. I think many have asked for it, but I havent seen a patch
with user yet :)

> > static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_sg(
> >                 struct dma_chan *chan,
> >                 struct scatterlist *dst_sg, unsigned int dst_nents,
> >                 struct scatterlist *src_sg, unsigned int src_nents,
> >                 unsigned long flags)
> > 
> > The problem with this API is that it would work only when src_sg and
> > dst_sg is of similar nature, if not then how should one go about
> > copying...should we fill without a care for dst_sg being different than
> > src_sg as long as total data to be copied has enough space in dst...
> At least for the CDMA the only requirement is that both buffers have the
> same total size.

I will merge if with a user but semantics need to be absolutely clear on
what is allowed and not, do I hear a volunteer ?
-- 
~Vinod

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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2021-04-23 17:20 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-23  1:19 [PATCH 0/4] Expand Xilinx CDMA functions Adrian Larumbe
2021-04-23  1:19 ` Adrian Larumbe
2021-04-23  1:19 ` [PATCH 1/4] dmaengine: xilinx_dma: Add extended address support in CDMA Adrian Larumbe
2021-04-23  1:19   ` Adrian Larumbe
2021-04-23  1:19 ` [PATCH 2/4] dmaengine: xilinx_dma: Add channel configuration setting callback Adrian Larumbe
2021-04-23  1:19   ` Adrian Larumbe
2021-04-23  1:19 ` [PATCH 3/4] dmaengine: xilinx_dma: Add CDMA SG transfer support Adrian Larumbe
2021-04-23  1:19   ` Adrian Larumbe
2021-04-23  1:19 ` [PATCH 4/4] dmaengine: xilinx_dma: Add device synchronisation callback Adrian Larumbe
2021-04-23  1:19   ` Adrian Larumbe
2021-04-23  6:33   ` Lars-Peter Clausen
2021-04-23  6:33     ` Lars-Peter Clausen
2021-04-23 11:49     ` [EXTERNAL] " Adrian Larumbe
2021-04-23 11:49       ` Adrian Larumbe
2021-04-23  9:17 ` [PATCH 0/4] Expand Xilinx CDMA functions Lars-Peter Clausen
2021-04-23  9:17   ` Lars-Peter Clausen
2021-04-23 11:38   ` [EXTERNAL] " Adrian Larumbe
2021-04-23 11:38     ` Adrian Larumbe
2021-04-23 13:24   ` Vinod Koul
2021-04-23 13:24     ` Vinod Koul
2021-04-23 13:51     ` Lars-Peter Clausen
2021-04-23 13:51       ` Lars-Peter Clausen
2021-04-23 14:36       ` [EXTERNAL] " Adrian Larumbe
2021-04-23 14:36         ` Adrian Larumbe
2021-04-23 17:20       ` Vinod Koul [this message]
2021-04-23 17:20         ` Vinod Koul
2021-06-01 10:29         ` radhey pandey
2021-06-01 10:29           ` radhey pandey
2021-07-02 14:23           ` [EXTERNAL] " Adrian Larumbe
2021-07-02 14:23             ` Adrian Larumbe
2021-07-05  3:53             ` Vinod Koul
2021-07-05  3:53               ` Vinod Koul

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