Subject: [PATCH 09/16] tty: serial: 8250_dma: Add a TX trigger workaround for AM33xx

From: [email-masked] (Sebastian Andrzej Siewior)
Date: Fri, 12 Sep 2014 11:51:22 +0200

On 09/12/2014 11:40 AM, Frans Klaver wrote:

> I'm not sure. I just reproduced this on a boneblack, using your uart_v9
> branch.
> 
>> This problem only pops-up if you use DMA. With disabled DMA you don't
>> see this, right?
> 
> I get the lockup both with and without DMA enabled. Here's the 8250
> config I use. Our full .config is attached in case it may provide
> something relevant.

Hmm. I have a bone black here. Can you tell what you did to get this
lockup? The port configuration (unless 115200 8N1) and what you did to
get this lockup.

> Something that may also help: when I have a lockup on the boneblack, dma
> is enabled and something is written to console like I described earlier,
> I get the following bad irq:

> Full dmesg is also attached.

This one should be stuffed by this:
	"[RFC] ARM: edma: unconditionally ack the error interrupt"
	https://lkml.org/lkml/2014/9/10/714

> Hope you find something useful in there.

> Thanks,
> Frans

Sebastian