* [PATCH] cbus-retu: Acquire mutex on write operation
@ 2011-02-26 23:34 Michael Buesch
2011-02-28 8:33 ` Felipe Balbi
0 siblings, 1 reply; 3+ messages in thread
From: Michael Buesch @ 2011-02-26 23:34 UTC (permalink / raw)
To: Tony Lindgren; +Cc: linux-omap, Felipe Balbi
The mutex has to be acquired on register write to avoid interference
with a simultaneous retu_set_clear_reg_bits operation.
Signed-off-by: Michael Buesch <mb@bu3sch.de>
---
Tested on n810.
Index: linux-omap-2.6/drivers/cbus/retu.c
===================================================================
--- linux-omap-2.6.orig/drivers/cbus/retu.c 2011-02-23 23:32:26.388763324 +0100
+++ linux-omap-2.6/drivers/cbus/retu.c 2011-02-26 23:27:08.772462280 +0100
@@ -120,7 +120,9 @@
{
struct retu *retu = dev_get_drvdata(child->parent);
+ mutex_lock(&retu->mutex);
__retu_write_reg(retu, reg, val);
+ mutex_unlock(&retu->mutex);
}
EXPORT_SYMBOL_GPL(retu_write_reg);
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] cbus-retu: Acquire mutex on write operation
2011-02-26 23:34 [PATCH] cbus-retu: Acquire mutex on write operation Michael Buesch
@ 2011-02-28 8:33 ` Felipe Balbi
2011-02-28 14:10 ` Michael Büsch
0 siblings, 1 reply; 3+ messages in thread
From: Felipe Balbi @ 2011-02-28 8:33 UTC (permalink / raw)
To: Michael Buesch; +Cc: Tony Lindgren, linux-omap, Felipe Balbi
On Sun, Feb 27, 2011 at 12:34:33AM +0100, Michael Buesch wrote:
> The mutex has to be acquired on register write to avoid interference
> with a simultaneous retu_set_clear_reg_bits operation.
>
> Signed-off-by: Michael Buesch <mb@bu3sch.de>
good catch, please do the same for retu_read_reg()
--
balbi
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] cbus-retu: Acquire mutex on write operation
2011-02-28 8:33 ` Felipe Balbi
@ 2011-02-28 14:10 ` Michael Büsch
0 siblings, 0 replies; 3+ messages in thread
From: Michael Büsch @ 2011-02-28 14:10 UTC (permalink / raw)
To: balbi; +Cc: Tony Lindgren, linux-omap
On Mon, 2011-02-28 at 10:33 +0200, Felipe Balbi wrote:
> On Sun, Feb 27, 2011 at 12:34:33AM +0100, Michael Buesch wrote:
> > The mutex has to be acquired on register write to avoid interference
> > with a simultaneous retu_set_clear_reg_bits operation.
> >
> > Signed-off-by: Michael Buesch <mb@bu3sch.de>
>
> good catch, please do the same for retu_read_reg()
I don't think this is necessary, because cbus_read_reg() and
cbus_write_reg() are atomic due to the cbus host->lock.
I think we can depend on this.
We could probably improve the comment on the lock in
cbus_transfer(), though.
--
Greetings Michael.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2011-02-26 23:34 [PATCH] cbus-retu: Acquire mutex on write operation Michael Buesch
2011-02-28 8:33 ` Felipe Balbi
2011-02-28 14:10 ` Michael Büsch
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