linux-kernel - RE: [PATCH] tty: serial: fsl_lpuart: don't enable receiver/transmitter before rx/tx dma ready

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Date:   Mon, 30 Jan 2023 03:02:21 +0000
From:   Sherry Sun <sherry.sun@....com>
To:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "jirislaby@...nel.org" <jirislaby@...nel.org>
CC:     "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH] tty: serial: fsl_lpuart: don't enable
 receiver/transmitter before rx/tx dma ready

Gentle ping...

Best Regards
Sherry

> -----Original Message-----
> From: Sherry Sun
> Sent: 2022年11月28日 13:04
> To: gregkh@...uxfoundation.org; jirislaby@...nel.org
> Cc: linux-serial@...r.kernel.org; linux-kernel@...r.kernel.org; dl-linux-imx
> <linux-imx@....com>
> Subject: [PATCH] tty: serial: fsl_lpuart: don't enable receiver/transmitter
> before rx/tx dma ready
> 
> lpuart32_setup_watermark_enable() will configure the UART FIFO and
> watermark, also enable the receiver and transmitter, this should be done
> after the rx/tx dma steup ready.
> 
> Also add lpuart32_hw_disable() to make sure the receiver/transmitter and
> interrupts are disabled during the dma steup.
> 
> Signed-off-by: Sherry Sun <sherry.sun@....com>
> ---
>  drivers/tty/serial/fsl_lpuart.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
> index 8918e08bb19e..bb12b328e224 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -1682,6 +1682,16 @@ static int lpuart_startup(struct uart_port *port)
>  	return 0;
>  }
> 
> +static void lpuart32_hw_disable(struct lpuart_port *sport) {
> +	unsigned long temp;
> +
> +	temp = lpuart32_read(&sport->port, UARTCTRL);
> +	temp &= ~(UARTCTRL_RIE | UARTCTRL_ILIE | UARTCTRL_RE |
> +		  UARTCTRL_TIE | UARTCTRL_TE);
> +	lpuart32_write(&sport->port, temp, UARTCTRL); }
> +
>  static void lpuart32_configure(struct lpuart_port *sport)  {
>  	unsigned long temp;
> @@ -1706,11 +1716,12 @@ static void lpuart32_hw_setup(struct
> lpuart_port *sport)
> 
>  	spin_lock_irqsave(&sport->port.lock, flags);
> 
> -	lpuart32_setup_watermark_enable(sport);
> +	lpuart32_hw_disable(sport);
> 
>  	lpuart_rx_dma_startup(sport);
>  	lpuart_tx_dma_startup(sport);
> 
> +	lpuart32_setup_watermark_enable(sport);
>  	lpuart32_configure(sport);
> 
>  	spin_unlock_irqrestore(&sport->port.lock, flags);
> --
> 2.17.1