Re: omap uart + dma issues (Re: [PATCH] tty: serial: 8250_omap: do not defer termios changes)

[Sekhar Nori]

On Wednesday 13 April 2016 05:30 AM, Peter Hurley wrote:

>>> - generates spurious uart interrupt for every rx dma transaction
>>>   (ie., necessitates acking every UART interrupt, even UART_IIR_NO_INT)
>>>   _Even with this workaround_, it still generates spurious interrupt warning
>>>   which shuts off interrupts for several ms while logging the error
>>>   message to the console, virtually guaranteeing lost data.
>>
>> as I wrote in my other email I think RDI should be disabled with DMA
> 
> 
> I'll test to see if disabling RDI eliminates the UART_IIR_NO_INT spurious
> interrupts.
> 
>> according the Intel manual and I *think* someone here reported that
>> they see the same problem.
> 
> Let's confirm with the Intel folks that this is true, which would argue
> for using the omap-style rx dma flow.

Andy Shevchenko pointed this out here: https://lkml.org/lkml/2016/2/23/588

Regards,
Sekhar