lkml.org 
[lkml]   [2021]   [Apr]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 02/26] serial: altera_jtaguart: drop low-latency workaround
On 2021-04-21 at 11:54:45 +0200, Johan Hovold <johan@kernel.org> wrote:
> Commit 53dd0ba7a6f4 ("tty: serial: altera_jtag: drop uart_port->lock
> before calling tty_flip_buffer_push()") claimed to address a locking
> issue but only provided a dubious lockdep splat from an unrelated
> driver, which in the end turned out to be due a broken local change
> carried by the author.
>
> Unfortunately these patches were merged before the issue had been
> analysed properly so the commit messages makes no sense whatsoever.
>
> The real issue was first seen on RT which at the time effectively always
> set the low_latency flag for all serial drivers by patching
> tty_flip_buffer_push(). This in turn revealed that many drivers did not
> handle the infamous low_latency behaviour which meant that data was
> pushed immediately to the line discipline instead of being deferred to a
> work queue.
>
> Since commit a9c3f68f3cd8 ("tty: Fix low_latency BUG"),
> tty_flip_buffer_push() always schedules a work item to push data to the
> line discipline and there's no need to keep any low_latency hacks
> around.
>
> Link: https://lore.kernel.org/linux-serial/cover.1376923198.git.viresh.kumar@linaro.org/
> Cc: Tobias Klauser <tklauser@distanz.ch>
> Signed-off-by: Johan Hovold <johan@kernel.org>

Acked-by: Tobias Klauser <tklauser@distanz.ch>

Thanks

\
 
 \ /
  Last update: 2021-04-21 12:12    [W:0.181 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site