Hi Peter
On 07/24/2014 01:32 AM, Peter Hurley wrote:
Hi Dirk,
On 07/23/2014 12:10 AM, Dirk Behme wrote:
Hi,
this is a question regarding the i.MX6 part (drivers/tty/serial/imx.c) of the commit
serial: Test for no tx data on tx restart
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c557d392fbf5badd693ea1946a4317c87a26a716
Talking with some i.MX6 experts about this, I've got the comment
-- cut --
The imx serial driver part of this commit isn't correct
as imx.c sends x_char in irq handler, not in imx_start_tx(),
-- cut --
What do you think?
Thanks for the comment.
Yeah, I missed that the imx driver handled x_char _at all_,
because how the imx driver is handling x_char looks broken.
For example, if data is already in the tx ring buffer,
imx_start_tx() will send that data before the x_char, and if
all the tx ring buffer data is sent successfully, the tx
interrupt is switched back off, so the x_char won't be sent.
imx_start_tx() doesn't do any actual data transfer, it only
switches tx interrupt on, and tx interrupt does the actual data
transfer, so if x_char is pending, it will always be sent before
the data in ring buffer.
Also, the imx driver doesn't send x_char in dma mode?
Yes, I think so.
Thanks,
Jiada
Regards,
Peter Hurley
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