linux-kernel - Re: [PATCH 1/2] tty: serial: fsl_lpuart: only enable Idle Line Interrupt for non-dma case

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Date:   Wed, 9 Nov 2022 14:02:04 +0200 (EET)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Sherry Sun <sherry.sun@....com>
cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        linux-serial <linux-serial@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, linux-imx@....com
Subject: Re: [PATCH 1/2] tty: serial: fsl_lpuart: only enable Idle Line
 Interrupt for non-dma case

On Wed, 9 Nov 2022, Sherry Sun wrote:

> For the lpuart driver, the Idle Line Interrupt Enable now is only needed
> for the CPU mode, so enable the UARTCTRL_ILIE at the correct place, and
> clear it when shutdown.
> 
> Also need to configure the suitable UARTCTRL_IDLECFG, now the value is
> 0x7, represent 128 idle characters will trigger the Idle Line Interrupt.
>
> Signed-off-by: Sherry Sun <sherry.sun@....com>
> ---
>  drivers/tty/serial/fsl_lpuart.c | 13 ++++++++-----
>  1 file changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
> index bd685491eead..f5a0a14fa366 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -179,7 +179,7 @@
>  #define UARTCTRL_SBK		0x00010000
>  #define UARTCTRL_MA1IE		0x00008000
>  #define UARTCTRL_MA2IE		0x00004000
> -#define UARTCTRL_IDLECFG	0x00000100
> +#define UARTCTRL_IDLECFG_OFF   8
>  #define UARTCTRL_LOOPS		0x00000080
>  #define UARTCTRL_DOZEEN		0x00000040
>  #define UARTCTRL_RSRC		0x00000020
> @@ -230,6 +230,8 @@
>  #define GLOBAL_RST_MIN_US	20
>  #define GLOBAL_RST_MAX_US	40
>  
> +#define UARTCTRL_IDLECFG	0x7
> +

GEN_MASK() to the correct bits directly?

>  /* Rx DMA timeout in ms, which is used to calculate Rx ring buffer size */
>  #define DMA_RX_TIMEOUT		(10)
>  
> @@ -1506,7 +1508,7 @@ static void lpuart32_setup_watermark(struct lpuart_port *sport)
>  	ctrl = lpuart32_read(&sport->port, UARTCTRL);
>  	ctrl_saved = ctrl;
>  	ctrl &= ~(UARTCTRL_TIE | UARTCTRL_TCIE | UARTCTRL_TE |
> -			UARTCTRL_RIE | UARTCTRL_RE);
> +			UARTCTRL_RIE | UARTCTRL_RE | UARTCTRL_ILIE);
>  	lpuart32_write(&sport->port, ctrl, UARTCTRL);
>  
>  	/* enable FIFO mode */
> @@ -1530,7 +1532,8 @@ static void lpuart32_setup_watermark_enable(struct lpuart_port *sport)
>  	lpuart32_setup_watermark(sport);
>  
>  	temp = lpuart32_read(&sport->port, UARTCTRL);
> -	temp |= UARTCTRL_RE | UARTCTRL_TE | UARTCTRL_ILIE;
> +	temp |= UARTCTRL_RE | UARTCTRL_TE;
> +	temp |= UARTCTRL_IDLECFG << UARTCTRL_IDLECFG_OFF;

FIELD_PREP() would probably be more appropriate for this? Then you can 
also drop the shift offset.

-- 
 i.

>  	lpuart32_write(&sport->port, temp, UARTCTRL);
>  }
>  
> @@ -1669,7 +1672,7 @@ static void lpuart32_configure(struct lpuart_port *sport)
>  	}
>  	temp = lpuart32_read(&sport->port, UARTCTRL);
>  	if (!sport->lpuart_dma_rx_use)
> -		temp |= UARTCTRL_RIE;
> +		temp |= UARTCTRL_RIE | UARTCTRL_ILIE;
>  	if (!sport->lpuart_dma_tx_use)
>  		temp |= UARTCTRL_TIE;
>  	lpuart32_write(&sport->port, temp, UARTCTRL);
> @@ -1770,7 +1773,7 @@ static void lpuart32_shutdown(struct uart_port *port)
>  
>  	/* disable Rx/Tx and interrupts */
>  	temp = lpuart32_read(port, UARTCTRL);
> -	temp &= ~(UARTCTRL_TE | UARTCTRL_RE |
> +	temp &= ~(UARTCTRL_TE | UARTCTRL_RE | UARTCTRL_ILIE |
>  			UARTCTRL_TIE | UARTCTRL_TCIE | UARTCTRL_RIE);
>  	lpuart32_write(port, temp, UARTCTRL);
>  
>