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: > > > Currently, the DMA channel calculates its data transferred only at network > > > device driver. When other devices like UART or SPI etc, transfers data by > > > DMA > > > mode, but it always shows 0 at /sys/class/dma/dma0chan*/bytes_transferred. > > > > Is that really a problem? I have never heard anyone complaining about > > it. Where are the reports of this? > Right, am not still getting the point on what is the problem that this series > is > trying to fix..
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. Thanks -Youquan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
