Re: [PATCH 1/2] serial: imx: cleanup imx_uart_disable_dma()

[Sebastian Reichel <sebastian.reichel@collabora.co.uk>]

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Hi,

On Tue, May 08, 2018 at 08:40:47AM +0200, Uwe Kleine-König wrote:
> On Mon, May 07, 2018 at 11:36:09PM +0200, Sebastian Reichel wrote:
> > Remove unrelated CTSC/CTS disabling from imx_uart_disable_dma() and
> > move it to imx_uart_shutdown(), which is the only user of the DMA
> > disabling function. This should not change the driver's behaviour,
> > but improves readability. After this change imx_uart_disable_dma()
> > does the reverse thing of imx_uart_enable_dma().
> > 
> > Suggested-by: Nandor Han <nandor.han@ge.com>
> > Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> > ---
> >  drivers/tty/serial/imx.c | 9 ++-------
> >  1 file changed, 2 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> > index c2fc6bef7a6f..3ca767b1162a 100644
> > --- a/drivers/tty/serial/imx.c
> > +++ b/drivers/tty/serial/imx.c
> > @@ -1291,18 +1291,13 @@ static void imx_uart_enable_dma(struct imx_port *sport)
> >  
> >  static void imx_uart_disable_dma(struct imx_port *sport)
> >  {
> > -	u32 ucr1, ucr2;
> > +	u32 ucr1;
> >  
> >  	/* clear UCR1 */
> >  	ucr1 = imx_uart_readl(sport, UCR1);
> >  	ucr1 &= ~(UCR1_RXDMAEN | UCR1_TXDMAEN | UCR1_ATDMAEN);
> >  	imx_uart_writel(sport, ucr1, UCR1);
> >  
> > -	/* clear UCR2 */
> > -	ucr2 = imx_uart_readl(sport, UCR2);
> > -	ucr2 &= ~(UCR2_CTSC | UCR2_CTS | UCR2_ATEN);
> > -	imx_uart_writel(sport, ucr2, UCR2);
> > -
> >  	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);
> >  
> >  	sport->dma_is_enabled = 0;
> > @@ -1447,7 +1442,7 @@ static void imx_uart_shutdown(struct uart_port *port)
> >  
> >  	spin_lock_irqsave(&sport->port.lock, flags);
> >  	ucr2 = imx_uart_readl(sport, UCR2);
> > -	ucr2 &= ~(UCR2_TXEN | UCR2_ATEN);
> > +	ucr2 &= ~(UCR2_TXEN | UCR2_CTSC | UCR2_CTS | UCR2_ATEN);
> >  	imx_uart_writel(sport, ucr2, UCR2);
> >  	spin_unlock_irqrestore(&sport->port.lock, flags);
> 
> While this doesn't change behaviour (which is of course good and
> intended here) I wonder if changing RTS is right here.
> 
> According to Documentation/serial/driver it is not.

Yes, looks like it should be removed completly. I suggest to keep
this in two different patches (move UCR2 handling first, then remove
RTS handling), so that we end up with simple and comprehensible patches.

-- Sebastian

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