Xilinx Zynq console rx not working

[Chris Johns]

On 14/8/21 12:40 am, Kinsey Moore wrote:
> On 8/13/2021 03:05, Chris Johns wrote:
>> Hi,
>>
>> I am bring up a major app on RTEMS 6 and LibBSD on custom Zynq hardware and I am
>> not getting any receive interrupts from the console UART. The same hardware
>> works with RTEMS 4.11 and RTEMS 5.
>>
>> I also do not see any console input with qemu and I thought this was something
>> in qemu but I am now not so sure.
>>
>> Anyone else seeing this issue?
>>
>> There has been a lot of playing with the Zynq UART driver recently.
> 
> I just went through and backed out all those changes you mentioned back to when
> the polled-only driver was split out and I still don't have functionality on
> Zynq under QEMU. Testing using fileio.exe, things are partially functional until
> I revert the change that enabled set_attributes. After the commit that enables
> set_attributes for the zynq UART, fileio produces output waiting for user input
> and will accept the first character to open the menu, but accepts no further
> input. Before that commit, the fileio test doesn't produce the expected output.
> 
> A full bisect would probably provide more accurate results, but this is what I
> could do quickly.
> 
> Note that ZynqMP fileio works on QEMU with current code and is fully
> operational. It is almost certainly the exact same emulated peripheral in QEMU
> and the hardware is supposed to be very close if not identical as well.

I have taken a closer look at the driver. I am receiving RX interrupts and the
characters are being queued however the receive FIFO trigger interrupt is only
raised when the FIFO reaches the set threshold of half the FIFO size. I suspect
there is an assumption the RX timeout will fire but it is not.

Chris