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Date: Tue, 29 Mar 2011 11:14:56 +0200
From: Uwe Kleine-König
<u.kleine-koenig@...gutronix.de>
To: Alan Cox <alan@...rguk.ukuu.org.uk>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
Sascha Hauer <s.hauer@...gutronix.de>,
linux-serial@...r.kernel.org, torvalds@...ux-foundation.org,
kernel@...gutronix.de
Subject: Re: Wrong GIT author ? also bugs: serial: Add uart driver for
i.MX23/28
Hello,
On Fri, Mar 18, 2011 at 11:29:20AM +0000, Alan Cox wrote:
> > serial: Add auart driver for i.MX23/28
> >
> > Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
>
> You have a few things that need fixing, one of which is quite nasty
I'm going to address these as Sascha is currently busy doing other
stuff.
> > + * Freescale STMP37XX/STMP378X Application UART driver
> > + *
> > + * Author: dmitry pervushin <dimka@...eddedalley.com>
>
> So its signed off by one person and without a signature from the author ?
> Is that intentional
The base for the driver was taken from a vendor BSP and polished to be
(nearly :-) ready for mainline. I don't know if Sascha tried to contact
Dimtry (I guess not) but keeping the original author listed is IMHO OK
as is using GIT_AUTHOR=Sascha when the polishing was non-trivial.
So maybe make this read:
Based on a driver by dmitry pervushin <dimka@...eddedalley.com>
and modified for mainline by Sascha Hauer <...>
?
> > +static void mxs_auart_rx_chars(struct mxs_auart_port *s)
> > +{
> > + struct tty_struct *tty = s->port.state->port.tty;
> > + u32 stat = 0;
>
> tty may be NULL at this point, in which case your code will try and push
> bits through a NULL pointer and crash
>
> A user can seek to make tty NULL at the right moment by judicious use of
> vhangup, and a remote device can use carrier signals and bit timing to
> mount an attack. See tty_port_tty_get() and/or hold the port lock over
> the IRQ as other drivers do. For the uart stuff I'd hold the port lock as
> the rest of the code in the uart layer sort of assumes that
OK
> > +static void mxs_auart_settermios(struct uart_port *u,
> > + struct ktermios *termios,
> > + struct ktermios *old)
>
> Minor things here
> - You need to set the termios bits to reflect the mode you actually set.
> So as you don't seem to support mark/space you need to clear the bit,
> ditto h/w flow control if not supported
>
> - You also need to report back the actual baud rate
I don't understand how to do this and didn't find something like that in
other drivers. (I checked amba-pl011.c and imx.c.) Also
Documentation/serial/driver doesn't describe this. (It is also silent
about CMSPAR and doesn't even advise to clear unsupported bits.)
Can you be a bit more verbose here?
> > +static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
> > +{
> > + u32 istatus, istat;
> > + struct mxs_auart_port *s = context;
> > + u32 stat = readl(s->port.membase + AUART_STAT);
>
> Your IRQ handler either needs to take the port lock or have the
> underlying methods do that or their own full locking, you aren't doing
> that.
OK, below you can find my current wip patch (yet untested on real hardware).
(If/when this looks OK for you and the above issue is addressed I will
create a proper patch.)
Best regards
Uwe
diff --git a/drivers/tty/serial/mxs-auart.c b/drivers/tty/serial/mxs-auart.c
index 7e02c9c..3b4c96a 100644
--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -1,17 +1,14 @@
/*
* Freescale STMP37XX/STMP378X Application UART driver
*
- * Author: dmitry pervushin <dimka@...eddedalley.com>
+ * Based on a driver by dmitry pervushin <dimka@...eddedalley.com>
+ * and modified for mainline by Sascha Hauer <s.hauer@...gutronix.de>
*
* Copyright 2008-2010 Freescale Semiconductor, Inc.
* Copyright 2008 Embedded Alley Solutions, Inc All Rights Reserved.
*
* The code contained herein is licensed under the GNU General Public
- * License. You may obtain a copy of the GNU General Public License
- * Version 2 or later at the following locations:
- *
- * http://www.opensource.org/licenses/gpl-license.html
- * http://www.gnu.org/copyleft/gpl.html
+ * License; version 2 or later.
*/
#include <linux/kernel.h>
@@ -286,6 +283,9 @@ static void mxs_auart_settermios(struct uart_port *u,
{
u32 bm, ctrl, ctrl2, div;
unsigned int cflag, baud;
+ unsigned long flags;
+
+ spin_lock_irqsave(&u->lock, flags);
cflag = termios->c_cflag;
@@ -303,11 +303,9 @@ static void mxs_auart_settermios(struct uart_port *u,
case CS7:
bm = 2;
break;
- case CS8:
+ default: /* CS8 */
bm = 3;
break;
- default:
- return;
}
ctrl |= AUART_LINECTRL_WLEN(bm);
@@ -368,13 +366,23 @@ static void mxs_auart_settermios(struct uart_port *u,
writel(ctrl, u->membase + AUART_LINECTRL);
writel(ctrl2, u->membase + AUART_CTRL2);
+
+ /* clear unsupported flags */
+ termios->c_cflag &= ~CMSPAR;
+
+ spin_unlock_irqrestore(&u->lock, flags);
}
static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
{
u32 istatus, istat;
struct mxs_auart_port *s = context;
- u32 stat = readl(s->port.membase + AUART_STAT);
+ unsigned long flags;
+ u32 stat;
+
+ spin_lock_irqsave(&s->port.lock, flags);
+
+ stat = readl(s->port.membase + AUART_STAT);
istatus = istat = readl(s->port.membase + AUART_INTR);
@@ -401,6 +409,8 @@ static irqreturn_t mxs_auart_irq_handle(int irq, void *context)
| AUART_INTR_CTSMIS),
s->port.membase + AUART_INTR_CLR);
+ spin_unlock_irqrestore(&s->port.lock, flags);
+
return IRQ_HANDLED;
}
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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