linux-kernel - Re: [PATCH 3/7] serial: imx: init dma_is

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Date:   Mon, 3 Jul 2017 08:52:21 +0200
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Romain Perier <romain.perier@...labora.com>
Cc:     Lothar Waßmann <LW@...O-electronics.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Nandor Han <nandor.han@...com>,
        linux-arm-kernel@...ts.infradead.org, linux-serial@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/7] serial: imx: init dma_is_{rx|tx}ing variables

On Fri, Jun 30, 2017 at 02:13:29PM +0200, Lothar Waßmann wrote:
> Hi,
> 
> On Fri, 30 Jun 2017 14:04:42 +0200 Romain Perier wrote:
> > From: Nandor Han <nandor.han@...com>
> > 
> > Initialize both dma_is_{rx|tx}ing variables when DMA is enabled to avoid
> > checking uninitialized variables if port shutdown is requested before
> > DMA channels get a chance to start.
> > 
> > Signed-off-by: Nandor Han <nandor.han@...com>
> > Signed-off-by: Romain Perier <romain.perier@...labora.com>
> > ---
> >  drivers/tty/serial/imx.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> > index 188063d..81fb413 100644
> > --- a/drivers/tty/serial/imx.c
> > +++ b/drivers/tty/serial/imx.c
> > @@ -1225,6 +1225,9 @@ static void imx_enable_dma(struct imx_port *sport)
> >  
> >  	imx_setup_ufcr(sport, TXTL_DMA, RXTL_DMA);
> >  
> > +	sport->dma_is_rxing = 0;
> > +	sport->dma_is_txing = 0;
> > +
> >  	sport->dma_is_enabled = 1;
> >  }
> >  
> sport is devm_kzalloc()ed, so the variables are initialized to 0 anyway.

I'd agree to Lothar's statement. Did you find this issue by inspection,
or does it fix a compiler warning? Do you think there is an actual
problem?

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |