From: Greg KH <gregkh@linuxfoundation.org>
To: drolevar@gmail.com
Cc: linux-serial@vger.kernel.org, Andrij Abyzov <aabyzov@slb.com>
Subject: Re: [PATCH v2 1/1] serial: 8250_fsl: Fix TX interrupt handling condition
Date: Mon, 28 Sep 2020 14:20:39 +0200 [thread overview]
Message-ID: <20200928122039.GA682772@kroah.com> (raw)
In-Reply-To: <20200928102841.43782-2-aabyzov@slb.com>
On Mon, Sep 28, 2020 at 12:28:41PM +0200, drolevar@gmail.com wrote:
> From: Andrij Abyzov <aabyzov@slb.com>
>
> This is the port of the commit db1b5bc047b3 ("serial: 8250: Fix TX
> interrupt handling condition") to the 8250_fsl irq handling logic.
>
> Interrupt handler checked THRE bit (transmitter holding register
> empty) in LSR to detect if TX fifo is empty.
> In case when there is only receive interrupts the TX handling
> got called because THRE bit in LSR is set when there is no
> transmission (FIFO empty). TX handling caused TX stop, which in
> RS-485 half-duplex mode actually resets receiver FIFO. This is not
> desired during reception because of possible data loss.
>
> The fix is to check if THRI is set in IER in addition of the TX
> fifo status. THRI in IER is set when TX is started and cleared
> when TX is stopped.
> This ensures that TX handling is only called when there is really
> transmission on going and an interrupt for THRE and not when there
> are only RX interrupts.
>
> Signed-off-by: Andrij Abyzov <aabyzov@slb.com>
> ---
> drivers/tty/serial/8250/8250_fsl.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/tty/serial/8250/8250_fsl.c b/drivers/tty/serial/8250/8250_fsl.c
> index 0d0c80905c58..ceac6cfce4c7 100644
> --- a/drivers/tty/serial/8250/8250_fsl.c
> +++ b/drivers/tty/serial/8250/8250_fsl.c
> @@ -71,7 +71,7 @@ int fsl8250_handle_irq(struct uart_port *port)
>
> serial8250_modem_status(up);
>
> - if (lsr & UART_LSR_THRE)
> + if ((lsr & UART_LSR_THRE) && (up->ier & UART_IER_THRI))
> serial8250_tx_chars(up);
>
> up->lsr_saved_flags = orig_lsr;
> --
> 2.25.1
>
What changed from v1?
That goes below the --- line, as is asked for in the submitting patches
document, right?
Can you fix that up and send a v3?
Also, why are you forwarding on a patch that you did not write or sign
off on? Please sign off on it yourself too.
thanks,
greg k-h
prev parent reply other threads:[~2020-09-28 12:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-28 10:28 [PATCH v2 0/1] serial: 8250_fsl: Fix TX interrupt handling condition drolevar
2020-09-28 10:28 ` [PATCH v2 1/1] " drolevar
2020-09-28 12:20 ` Greg KH [this message]
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