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

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Date:   Thu, 17 Nov 2022 22:10:31 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     delisun <delisun@...eo.com.cn>
Cc:     linux@...linux.org.uk, jirislaby@...nel.org,
        linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] serial: pl011: Do not clear RX FIFO & RX interrupt in
 unthrottle.

On Wed, Nov 09, 2022 at 06:58:22PM +0800, 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.
> 
> 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)
> -- 
> 2.25.1
> 
> 
> 

How was this tested?

What commit id does this fix?

And your email is showing up as unvalidated, please fix your email
infrastructure to properly verify messages.

thanks,

greg k-h