[PATCH 1/1] tty: serial: imx: disable ageing timer interrupt if dma in use

[Han, Nandor (GE Healthcare)]

> -----Original Message-----
> From: linux-serial-owner at vger.kernel.org [mailto:linux-serial-
> owner at vger.kernel.org] On Behalf Of Troy Kisky
> Sent: 07 October 2017 04:47
> To: gregkh at linuxfoundation.org
> Cc: fabio.estevam at nxp.com; l.stach at pengutronix.de; u.kleine-
> koenig at pengutronix.de; linux-serial at vger.kernel.org; linux-arm-
> kernel at lists.infradead.org; Troy Kisky <troy.kisky at boundarydevices.com>
> Subject: EXT: [PATCH 1/1] tty: serial: imx: disable ageing timer interrupt if
> dma in use
> 
> Since commit 4dec2f119e86 ("imx-serial: RX DMA startup latency")
> 
> the interrupt routine no longer will start rx dma.

I think you have 2 commits here: 
- one that disables ageing timer when DMA is in use
- one that cleans the leftovers after 4dec2f119e86.

> 
> Signed-off-by: Troy Kisky <troy.kisky at boundarydevices.com>
> ---
>  drivers/tty/serial/imx.c | 34 ++--------------------------------
>  1 file changed, 2 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index
> dfeff3951f93..15b0ecb4cf60 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -732,29 +732,6 @@ static void imx_disable_rx_int(struct imx_port
> *sport)  }
> 
>  static void clear_rx_errors(struct imx_port *sport); -static int
> start_rx_dma(struct imx_port *sport);
> -/*
> - * If the RXFIFO is filled with some data, and then we
> - * arise a DMA operation to receive them.
> - */
> -static void imx_dma_rxint(struct imx_port *sport) -{
> -	unsigned long temp;
> -	unsigned long flags;
> -
> -	spin_lock_irqsave(&sport->port.lock, flags);
> -
> -	temp = readl(sport->port.membase + USR2);
> -	if ((temp & USR2_RDR) && !sport->dma_is_rxing) {
> -
> -		imx_disable_rx_int(sport);
> -
> -		/* tell the DMA to receive the data. */
> -		start_rx_dma(sport);
> -	}
> -
> -	spin_unlock_irqrestore(&sport->port.lock, flags);
> -}
> 
>  /*
>   * We have a modem side uart, so the meanings of RTS and CTS are inverted.
> @@ -816,11 +793,8 @@ static irqreturn_t imx_int(int irq, void *dev_id)
>  	sts = readl(sport->port.membase + USR1);
>  	sts2 = readl(sport->port.membase + USR2);
> 
> -	if (sts & (USR1_RRDY | USR1_AGTIM)) {
> -		if (sport->dma_is_enabled)
> -			imx_dma_rxint(sport);
> -		else
> -			imx_rxint(irq, dev_id);
> +	if (!sport->dma_is_enabled && (sts & (USR1_RRDY |
> USR1_AGTIM))) {
> +		imx_rxint(irq, dev_id);

I don't think we need the check `!sport->dma_is_enabled ` since RRDY and AGTIM interrupts should be disable when DMA is enabled.

>  		ret = IRQ_HANDLED;
>  	}
> 
> @@ -1207,10 +1181,6 @@ static void imx_enable_dma(struct imx_port
> *sport)
>  	temp |= UCR1_RDMAEN | UCR1_TDMAEN | UCR1_ATDMAEN;
>  	writel(temp, sport->port.membase + UCR1);
> 
> -	temp = readl(sport->port.membase + UCR2);
> -	temp |= UCR2_ATEN;
> -	writel(temp, sport->port.membase + UCR2);
> -

I think this should be moved to imx_startup. At least RRDY is configured there. 

<snip>

Regards,
Nandor