linux-kernel - Re: [PATCH 1/2] serial: imx: cleanup imx_uart_disable

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180508112726.nyxrebcuwwdq5npy@earth.universe>
Date:   Tue, 8 May 2018 13:27:26 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.co.uk>
To:     Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, linux-serial@...r.kernel.org,
        Fabio Estevam <fabio.estevam@....com>,
        Shawn Guo <shawnguo@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] serial: imx: cleanup imx_uart_disable_dma()

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@...com>
> > Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.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

Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)