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From: Itai Handler <itai.handler@gmail.com>
To: Michel Macena Oliveira <michel@austral-dynamics.com>
Cc: linux-rt-users@vger.kernel.org
Subject: Re: Serial port driver usage and status
Date: Thu, 16 Jul 2020 22:26:23 +0300
Message-ID: <CAFpOueQm5MhbrV53=kAcw=ES2LzsZPkmX2SqTVKuYTf0QDt=7w@mail.gmail.com> (raw)
In-Reply-To: <CAKkbJ-yB4XGuexzmwfkR8g76HR8iCkXaHsXaLaS6V+Wfy86bvg@mail.gmail.com>

Hi Michel,

On 7/16/20, Michel Macena Oliveira <michel@austral-dynamics.com> wrote:
> Hi, sorry for my newbie question,
> What is the status of the serial port driver?
> I've written some code to use serial ports  for the generic kernel linux,
> And now I want to write something similar for the real time kernel, do
> I have to use some specific library, flags or something or is it just
> the same settings?
>
> I'm asking because now I need to take into account the serial access
> in the scheduler to ensure a real time behavior .
>
> Any help, advice, hint or tips would be appreciated.
>

Do you mean that you wrote some code that works with a /dev/tty* serial port?

In some kernel versions (e.g 4.19) we saw high latencies in the rx
path of serial drivers.
I think that this is due to rx handled in the context of a workqueue
which also handles other system activities.
We found a workaround to this problem. If I remember correctly we
create a dedicated thread for the port and assign it a high priority.

Itai Handler

  reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-16 17:29 Michel Macena Oliveira
2020-07-16 19:26 ` Itai Handler [this message]
2020-07-16 20:20   ` Michel Macena Oliveira
2020-07-16 20:40     ` Itai Handler
2020-07-16 20:40     ` Austin Schuh
2020-08-05 18:29       ` Michel Macena Oliveira
2020-08-05 19:21         ` Itai Handler
2020-08-05 19:52           ` Michel Macena Oliveira
2020-08-06 19:56             ` Itai Handler

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