Messages in this thread | | | Date | Tue, 15 Oct 2013 08:55:20 -0700 | Subject | Re: [PATCH 1/2] dma: Add interface to calculate data transferred | From | Dan Williams <> |
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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.
-- Dan
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