Hi,
On 11/15/2012 05:20 AM, Huang Shijie wrote:
于 2012年11月13日 17:42, Lauri Hintsala 写道:
Hi Huang,
DMA support doesn't work with latest stable v3.6.5 or development
3.7-rc5 kernels. I get following error message when I open the serial
port /dev/ttyAPP0:
[ 48.730000] mxs-auart 8006a000.serial: step 1 error
[ 48.750000] mxs-auart 8006a000.serial: We can not start up the DMA.
I tested this patch set in imx28-evk board Rev C with linux-next-20121114.
it works fine.
Maybe you can try the linux-next code.
I tested linux-next-20121114 on apx4devkit (imx28 based device) and I
got the same error message:
# stty -F /dev/ttyAPP0 crtscts; microcom /dev/ttyAPP0 -s 115200
[ 133.710000] mxs-auart 8006a000.serial: step 1 error
[ 133.720000] mxs-auart 8006a000.serial: We can not start up the DMA.
About the flow control:
If we do not enable the HW flow control, the data may lost. And I do not
know how to handle with the Xon/Xoff when the DMA is supported.
I do not have the answer but it is already implemented in Freescale's
reference kernel
(http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/tree/drivers/serial/mxs-auart.c?h=imx_2.6.35_11.09.01).
So I think it is possible to handle all data without HW flow control.
Best Regards,
Lauri Hintsala
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