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: Tue, 3 Mar 2020 10:02:54 +0530 [thread overview]
Message-ID: <20200303043254.GN4148@vkoul-mobl> (raw)
In-Reply-To: <20200302073728.GB9177@pendragon.ideasonboard.com>
Hi Laurent,
On 02-03-20, 09:37, Laurent Pinchart wrote:
> > I would be more comfortable in calling an API to do so :)
> > The flow I am thinking is:
> >
> > - prep cyclic1 txn
> > - submit cyclic1 txn
> > - call issue_pending() (cyclic one starts)
> >
> > - prep cyclic2 txn
> > - submit cyclic2 txn
> > - signal_cyclic1_txn aka terminate_cookie()
> > - cyclic1 completes, switch to cyclic2 (dmaengine driver)
> > - get callback for cyclic1 (optional)
> >
> > To check if hw supports terminate_cookie() or not we can check if the
> > callback support is implemented
>
> Two questions though:
>
> - Where is .issue_pending() called for cyclic2 in your above sequence ?
> Surely it should be called somewhere, as the DMA engine API requires
> .issue_pending() to be called for a transfer to be executed, otherwise
> it stays in the submitted but not pending queue.
Sorry missed that one, I would do that after submit cyclic2 txn step and
then signal signal_cyclic1_txn termination
> - With the introduction of a new .terminate_cookie() operation, we need
> to specify that operation for all transfer types. What's its
Correct
> envisioned semantics for non-cyclic transfers ? And how do DMA engine
> drivers report that they support .terminate_cookie() for cyclic
> transfers but not for other transfer types (the counterpart of
> reporting, in my proposition, that .issue_pending() isn't supported
> replace the current cyclic transfer) ?
Typically for dmaengine controller cyclic is *not* a special mode, only
change is that a list provided to controller is circular.
So, the .terminate_cookie() should be a feature for all type of txn's.
If for some reason (dont discount what hw designers can do) a controller
supports this for some specific type(s), then they should return
-ENOTSUPP for cookies that do not support and let the caller know.
--
~Vinod
next prev parent reply other threads:[~2020-03-03 4:32 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
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 [this message]
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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