Regression: serial: imx: overrun errors on debug UART

[Linux regression tracking #adding (Thorsten Leemhuis)]

[TLDR: I'm adding this report to the list of tracked Linux kernel
regressions; the text you find below is based on a few templates
paragraphs you might have encountered already in similar form.
See link in footer if these mails annoy you.]

On 24.03.23 09:57, Stefan Wahren wrote:
> Hi,
> 
> after switching to Linux 6.1.21 on our Tarragon board (i.MX6ULL SoC), we
> experience the following issues with the debug UART (115200 baud, 8N1,
> no hardware flow control):
> 
> - overrun errors if we paste in multiple text lines while system is idle
> - no reaction to single key strokes while system is on higher load
> 
> After reverting 7a637784d517 ("serial: imx: reduce RX interrupt
> frequency") the issue disappear.
> 
> Maybe it's worth to mention that the Tarragon board uses two additional
> application UARTs with similiar baud rates (9600 - 115200 baud, no
> hardware flow control) for RS485 communication, but there are no overrun
> errors (with and without the mention change).

Thanks for the report. To be sure the issue doesn't fall through the
cracks unnoticed, I'm adding it to regzbot, the Linux kernel regression
tracking bot:

#regzbot ^introduced 7a637784d517
#regzbot title serial: imx: overrun errors on debug UART
#regzbot ignore-activity

This isn't a regression? This issue or a fix for it are already
discussed somewhere else? It was fixed already? You want to clarify when
the regression started to happen? Or point out I got the title or
something else totally wrong? Then just reply and tell me -- ideally
while also telling regzbot about it, as explained by the page listed in
the footer of this mail.

Developers: When fixing the issue, remember to add 'Link:' tags pointing
to the report (the parent of this mail). See page linked in footer for
details.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
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