On 18.07.2018 14:33, Dmitry Osipenko wrote:
On Friday, 13 July 2018 14:32:42 MSK David R. Piegdon wrote:
Hi,
a while back I sent a few mails regarding spurious interrupts in the
UARTA (hsuart) block of the Tegra2 SoC, when using the 8250 driver for
it instead of the hsuart driver. After going down a pretty deep
debugging/testing hole, I think I found a patch that fixes the issue. So
far testing in a reboot-cycle suggests that the error frequency dropped
from >3% of all reboots to at least <0.05% of all reboots. Tests
continue to run over the weekend.
The patch below already is a second iteration; the first did not reset
the MCR or contain the lines below '// clear interrupts'. This resulted
in no more spurious interrupts, but in a few % of spurious interrupts
that were recovered the UART block did not receive any characters any
more. So further resetting was required to fully reacquire operational
state of the UART block.
I'd love any comments/suggestions on this!
I'm wondering whether later Tegra's have that issue as well, maybe Mikko
knows?
My understanding is that the issue is on all generations.
Instead of #ifdef-ing T20 in the code, there probably should be some kind of a
port flag. Please send a proper patch and follow suggestions from tty/
maintainers.
Yep - if possible to do in a tegra-specific callback, that would be
nice, but I'm not sure if that's possible.
Cheers,
Mikko
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