linux-kernel - Re: [PATCH] serial: pl011: Do not clear RX FIFO & RX interrupt in unthrottle.

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Date:   Thu, 10 Nov 2022 12:24:41 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     delisun <delisun@...eo.com.cn>
cc:     linux@...linux.org.uk,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        linux-serial <linux-serial@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] serial: pl011: Do not clear RX FIFO & RX interrupt in
 unthrottle.

On Thu, 10 Nov 2022, delisun wrote:

> Clearing the RX FIFO will cause data loss.
> Copy the pl011_enabl_interrupts implementation, and remove the clear
> interrupt and FIFO part of the code.
> 
> Fixes: 211565b10099 ("serial: pl011: UPSTAT_AUTORTS requires .throttle/unthrottle")
> Signed-off-by: delisun <delisun@...eo.com.cn>
> ---
>  drivers/tty/serial/amba-pl011.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> index 5cdced39eafd..08034e5dcec0 100644
> --- a/drivers/tty/serial/amba-pl011.c
> +++ b/drivers/tty/serial/amba-pl011.c
> @@ -1828,8 +1828,17 @@ static void pl011_enable_interrupts(struct uart_amba_port *uap)
>  static void pl011_unthrottle_rx(struct uart_port *port)
>  {
>  	struct uart_amba_port *uap = container_of(port, struct uart_amba_port, port);
> +	unsigned long flags;
>  
> -	pl011_enable_interrupts(uap);
> +	spin_lock_irqsave(&uap->port.lock, flags);
> +
> +	uap->im = UART011_RTIM;
> +	if (!pl011_dma_rx_running(uap))
> +		uap->im |= UART011_RXIM;
> +
> +	pl011_write(uap->im, uap, REG_IMSC);
> +
> +	spin_unlock_irqrestore(&uap->port.lock, flags);
>  }
>  
>  static int pl011_startup(struct uart_port *port)

Thanks.

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com> 

-- 
 i.