From: Vinod Koul <vinod.koul@intel.com>
To: Nandor Han <nandor.han@ge.com>
Cc: =Dan Williams <dan.j.williams@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>,
dmaengine@vger.kernel.org, linux-serial@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: EXT: Re: [PATCH RFC 1/4] dma: imx-sdma - reduce transfer latency for DMA cyclic clients
Date: Sat, 2 Jul 2016 22:57:05 +0530 [thread overview]
Message-ID: <20160702172704.GV14945@localhost> (raw)
In-Reply-To: <57768552.6060407@ge.com>
On Fri, Jul 01, 2016 at 05:59:30PM +0300, Nandor Han wrote:
>
>
> On 28/06/16 17:34, Vinod Koul wrote:
> >On Thu, Jun 09, 2016 at 03:16:30PM +0300, Nandor Han wrote:
> >>Having the SDMA driver use a tasklet for running the clients
> >>callback introduce some issues:
> >> - probability to have desynchronized data because of the
> >> race condition created since the DMA transaction status
> >> is retrieved only when the callback is executed, leaving
> >> plenty of time for transaction status to get altered.
> >> - inter-transfer latency which can leave channels idle.
> >>
> >>Move the callback execution, for cyclic channels, to SDMA
> >>interrupt (as advised in `Documentation/dmaengine/provider.txt`)
> >>to (a)reduce the inter-transfer latency and (b) eliminate the
> >>race condition possibility where DMA transaction status might
> >>be changed by the time is read.
> >>
> >>The responsibility of the SDMA interrupt latency
> >>is moved to the SDMA clients which case by case should defer
> >>the work to bottom-halves when needed.
> >
> >Both of these look fine. Please change the patch titles to dmaengine: xxxx
> >
> >Are these going to be merged thru dmaengine tree or serial one?
> >
>
> I will send soon a V2 where I will fix the titles. If you are OK
> with all the patchset it can be merged to dmaengine tree, otherwise
> probably goes to serial one.
Sure I can merge all.. provided ACKs on other patches.
--
~Vinod
next prev parent reply other threads:[~2016-07-02 17:27 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-09 12:16 [PATCH RFC 0/4] serial,dma: use DMA cyclic for IMX UART driver Nandor Han
2016-06-09 12:16 ` [PATCH RFC 1/4] dma: imx-sdma - reduce transfer latency for DMA cyclic clients Nandor Han
2016-06-28 14:34 ` Vinod Koul
2016-07-01 14:59 ` EXT: " Nandor Han
2016-07-02 17:27 ` Vinod Koul [this message]
2016-07-14 8:32 ` Peter Senna Tschudin
2016-06-09 12:16 ` [PATCH RFC 2/4] dma: imx-sdma - update the residue calculation for cyclic channels Nandor Han
2016-06-09 12:16 ` [PATCH RFC 3/4] serial: imx-serial - update UART IMX driver to use cyclic DMA Nandor Han
2016-06-09 12:16 ` [PATCH RFC 4/4] serial: imx-serial - update RX error counters when DMA is used Nandor Han
2016-08-08 12:38 ` [PATCH 0/4] serial,dmaengine: use DMA cyclic for IMX UART driver Nandor Han
2016-08-08 12:38 ` [PATCH 1/4] dmaengine: imx-sdma - reduce transfer latency for DMA cyclic clients Nandor Han
2016-08-08 12:38 ` [PATCH 2/4] dmaengine: imx-sdma - update the residue calculation for cyclic channels Nandor Han
2016-08-08 12:38 ` [PATCH 3/4] serial: imx-serial - update UART IMX driver to use cyclic DMA Nandor Han
2016-08-08 12:38 ` [PATCH 4/4] serial: imx-serial - update RX error counters when DMA is used Nandor Han
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