From: Vinod Koul <vkoul@kernel.org>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>,
dmaengine@vger.kernel.org, Michal Simek <michal.simek@xilinx.com>,
Hyun Kwon <hyun.kwon@xilinx.com>,
Tejas Upadhyay <tejasu@xilinx.com>,
Satish Kumar Nagireddy <SATISHNA@xilinx.com>
Subject: Re: [PATCH v3 2/6] dmaengine: Add interleaved cyclic transaction type
Date: Thu, 13 Feb 2020 18:59:38 +0530 [thread overview]
Message-ID: <20200213132938.GF2618@vkoul-mobl> (raw)
In-Reply-To: <20200210140618.GA4727@pendragon.ideasonboard.com>
Hi Laurent,
On 10-02-20, 16:06, Laurent Pinchart wrote:
> > >> The use case here is not to switch to a new configuration, but to switch
> > >> to a new buffer. If the transfer had to be terminated manually first,
> > >> the DMA engine would potentially miss a frame, which is not acceptable.
> > >> We need an atomic way to switch to the next transfer.
> > >
> > > So in this case you have, let's say a cyclic descriptor with N buffers
> > > and they are cyclically capturing data and providing to client/user..
> >
> > For the display case it's cyclic over a single buffer that is repeatedly
> > displayed over and over again until a new one replaces it, when
> > userspace wants to change the content on the screen. Userspace only has
> > to provide a new buffer when content changes, otherwise the display has
> > to keep displaying the same one.
>
> Is the use case clear enough, or do you need more information ? Are you
> fine with the API for this kind of use case ?
So we *know* when a new buffer is being used?
IOW would it be possible for display (rather a dmaengine facing display wrapper) to detect that we are reusing an
old buffer and keep the cyclic and once detected prepare a new
descriptor, submit a new one and then terminate old one which should
trigger next transaction to be submitted
Would that make sense here?
--
~Vinod
next prev parent reply other threads:[~2020-02-13 13:29 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-23 2:29 [PATCH v3 0/6] dma: Add Xilinx ZynqMP DPDMA driver Laurent Pinchart
2020-01-23 2:29 ` [PATCH v3 1/6] dt: bindings: dma: xilinx: dpdma: DT bindings for Xilinx DPDMA Laurent Pinchart
2020-01-23 2:29 ` [PATCH v3 2/6] dmaengine: Add interleaved cyclic transaction type Laurent Pinchart
2020-01-23 8:03 ` Peter Ujfalusi
2020-01-23 8:43 ` Vinod Koul
2020-01-23 8:51 ` Peter Ujfalusi
2020-01-23 12:23 ` Laurent Pinchart
2020-01-24 6:10 ` Vinod Koul
2020-01-24 8:50 ` Laurent Pinchart
2020-02-10 14:06 ` Laurent Pinchart
2020-02-13 13:29 ` Vinod Koul [this message]
2020-02-13 13:48 ` Laurent Pinchart
2020-02-13 14:07 ` Vinod Koul
2020-02-13 14:15 ` Peter Ujfalusi
2020-02-13 16:52 ` Laurent Pinchart
2020-02-14 4:23 ` Vinod Koul
2020-02-14 16:22 ` Laurent Pinchart
2020-02-17 10:00 ` Peter Ujfalusi
2020-02-19 9:25 ` Vinod Koul
2020-02-26 16:30 ` Laurent Pinchart
2020-03-02 3:47 ` Vinod Koul
2020-03-02 7:37 ` Laurent Pinchart
2020-03-03 4:32 ` Vinod Koul
2020-03-03 19:22 ` Laurent Pinchart
2020-03-04 5:13 ` Vinod Koul
2020-03-04 8:01 ` Laurent Pinchart
2020-03-04 15:37 ` Vinod Koul
2020-03-04 16:00 ` Laurent Pinchart
2020-03-04 16:24 ` Vinod Koul
[not found] ` <20200311155248.GA4772@pendragon.ideasonboard.com>
2020-03-18 15:14 ` Laurent Pinchart
2020-03-25 16:00 ` Laurent Pinchart
2020-03-26 7:02 ` Vinod Koul
2020-04-08 17:00 ` Laurent Pinchart
2020-04-15 15:12 ` Laurent Pinchart
2020-03-06 14:49 ` Peter Ujfalusi
2020-03-11 23:15 ` Laurent Pinchart
2020-02-26 16:24 ` Laurent Pinchart
2020-03-02 3:42 ` Vinod Koul
2020-01-24 7:20 ` Peter Ujfalusi
2020-01-24 7:38 ` Peter Ujfalusi
2020-01-24 8:58 ` Laurent Pinchart
2020-01-24 8:56 ` Laurent Pinchart
2020-01-23 2:29 ` [PATCH v3 3/6] dmaengine: virt-dma: Use lockdep to check locking requirements Laurent Pinchart
2020-01-23 2:29 ` [PATCH v3 4/6] dmaengine: xilinx: dpdma: Add the Xilinx DisplayPort DMA engine driver Laurent Pinchart
2020-01-23 2:29 ` [PATCH v3 5/6] dmaengine: xilinx: dpdma: Add debugfs support Laurent Pinchart
2020-01-23 2:29 ` [PATCH v3 6/6] arm64: dts: zynqmp: Add DPDMA node Laurent Pinchart
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