From: Vinod Koul <vinod.koul@intel.com>
To: Dan Williams <dan.j.williams@intel.com>
Cc: Youquan Song <youquan.song@linux.jf.intel.com>,
Greg KH <gregkh@linuxfoundation.org>,
Youquan Song <youquan.song@intel.com>,
andriy.shevchenko@intel.com, mika.westerberg@intel.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] dma: Add interface to calculate data transferred
Date: Wed, 16 Oct 2013 11:08:57 +0530 [thread overview]
Message-ID: <20131016053857.GV2954@intel.com> (raw)
In-Reply-To: <CAPcyv4jJSgM7EmDMW-rcjVCnC6-95+qeU9yf+yxD-wMCcQ8amg@mail.gmail.com>
On Tue, Oct 15, 2013 at 08:55:20AM -0700, Dan Williams wrote:
> On Tue, Oct 15, 2013 at 11:31 AM, Youquan Song
> <youquan.song@linux.intel.com> wrote:
> > On Sun, Oct 13, 2013 at 08:56:33PM +0530, Vinod Koul wrote:
> >> On Fri, Oct 11, 2013 at 06:33:43AM -0700, Greg KH wrote:
> >> > On Fri, Oct 11, 2013 at 05:42:17PM -0400, Youquan Song wrote:
> > The issue is that when I using UART to transfer data between to COMs
> > which using Designware DMA controller channel. But I check the specific
> > DMA channel by "cat /sys/class/dma/dma0chan3/bytes_transferred", but it
> > should all "0". I have transferred data by UART port, why its DMA
> > channel report "0" bytes transferred? So I guess that it is possible
> > the DMA device driver issue or the data does not use the Designware DMA channel
> > fro transferred. After check the code, I notice only when the DMA
> > channel used by network device driver and it will record how much data has been
> > tranferred, why other device driver will not calculate it. Since DMA
> > channel is used by other device driver, why only network is specific? since it is
> > common interface, the current /sys/class/dma/dma0chan*/bytes_transferred has
> > much possibility to mislead the user.
>
> Yes, and for that reason I think we should delete "
> /sys/class/dma/dma0chan*/bytes_transferred" it really serves no useful
> purpose besides "is my dma channel working" which can be determined by
> other means.
Well am going to take it a bit further and ask you why do we need the
/sys/class/dma? I have never used it for slave work.
Does it get used anywhere in async_tx?
--
~Vinod
next prev parent reply other threads:[~2013-10-16 6:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-11 21:42 DMA: Calculate how many data transferred by DMA Youquan Song
2013-10-11 21:42 ` [PATCH 1/2] dma: Add interface to calculate data transferred Youquan Song
2013-10-11 10:22 ` Shevchenko, Andriy
2013-10-11 13:33 ` Greg KH
2013-10-13 15:26 ` Vinod Koul
2013-10-15 18:31 ` Youquan Song
2013-10-15 15:30 ` Greg KH
2013-10-15 15:55 ` Dan Williams
2013-10-15 16:17 ` Greg KH
2013-10-16 5:38 ` Vinod Koul [this message]
2013-10-16 8:36 ` Shevchenko, Andriy
2013-10-16 7:57 ` Vinod Koul
2013-10-16 9:13 ` Shevchenko, Andriy
2013-10-16 14:12 ` Greg KH
2013-10-16 15:07 ` Vinod Koul
2013-10-16 18:17 ` Dan Williams
2013-10-11 21:42 ` [PATCH 2/2] dma: calculate the data tranferred by 8250 Youquan Song
2013-10-11 13:32 ` Greg KH
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