linux-kernel - Re: [PATCH] Revert "serial: 8250: Fix clearing FIFOs in RS485 mode again"

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Message-ID: <CAAEAJfAQ9=B6sm=Ard+YTDN5g5r03o=t9xU3Nu2QaKrXXZ4pGw@mail.gmail.com>
Date:   Sun, 16 Dec 2018 19:28:22 -0300
From:   Ezequiel Garcia <ezequiel@...guardiasur.com.ar>
To:     Paul Burton <paul.burton@...s.com>
Cc:     Marek Vasut <marex@...x.de>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Paul Burton <pburton@...ecomp.com>,
        Daniel Jedrychowski <avistel@...il.com>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
        stable <stable@...r.kernel.org>,
        Ezequiel Garcia <ezequiel@...labora.com>
Subject: Re: [PATCH] Revert "serial: 8250: Fix clearing FIFOs in RS485 mode again"

On Sun, 16 Dec 2018 at 19:24, Paul Burton <paul.burton@...s.com> wrote:
>
> Hi Ezequiel,
>
> On Sun, Dec 16, 2018 at 06:52:53PM -0300, Ezequiel Garcia wrote:
> > diff --git a/drivers/tty/serial/8250/8250_port.c
> > b/drivers/tty/serial/8250/8250_port.c
> > index c39482b96111..fac19cbc51d1 100644
> > --- a/drivers/tty/serial/8250/8250_port.c
> > +++ b/drivers/tty/serial/8250/8250_port.c
> > @@ -2209,10 +2209,11 @@ int serial8250_do_startup(struct uart_port *port)
> >         /*
> >          * Clear the FIFO buffers and disable them.
> >          * (they will be reenabled in set_termios())
> >          */
> >         serial8250_clear_fifos(up);
> > +       serial_out(up, UART_FCR, 0);
> >
> >         /*
> >          * Clear the interrupt registers.
> >          */
> >         serial_port_in(port, UART_LSR);
> >
>
> This helps, but it only addresses one part of one of the 4 reasons I
> listed as motivation for my revert. For example serial8250_do_shutdown()
> also clearly intends to disable the FIFOs.
>

OK. So, let's fix that :-)

By all means, it would be really nice to push forward and fix the garbage
issue on JZ4780, as well as the transmission issue on AM335x.

AM335x is a wildly popular platform, and it's not funny to break it.
So, let's please stop discussing which board we'll break and just fix both.
-- 
Ezequiel García, VanguardiaSur
www.vanguardiasur.com.ar