Hi Uli,
On Fri, Feb 16, 2018 at 3:27 PM, Ulrich Hecht
<ulrich.hecht+renesas@xxxxxxxxx> wrote:
> On Thu, Feb 15, 2018 at 2:12 PM, Wolfram Sang <wsa@xxxxxxxxxxxxx> wrote:
>>> This can be prevented by doing a dummy read of the RX data register.
>>
>> Just so I understand the issue correctly: We are reading the register to
>> throw the content away to prevent it being used in the TTY buffers?
>
> Not quite. The problem was that if the buffers are full,
> sci_receive_chars() returned immediately without reading anything from
> the data register, and that led to a lockup. I am not fully sure why
> that is so (I arrived at the fix by examining how the different code
> paths look from the serial controller's perspective), but dropping
> data here fixes it. At this point buffers are full, so any data
> received will have to be discarded anyway.
Do you get an interrupt storm, from the receive or overrun interrupt?
Anyway, the patch makes sense to me, so
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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