Re: Spurious timeouts in mvmdio

[Leigh Brown]

On 2013-12-16 18:07, Nicolas Schichan wrote:
> On 12/04/2013 12:42 AM, Russell King - ARM Linux wrote:
> > Alternatively, code it like this instead.
> >
> >   drivers/net/ethernet/marvell/mvmdio.c |   32 
> > +++++++++++++++-----------------
> >   1 files changed, 15 insertions(+), 17 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/marvell/mvmdio.c 
> > b/drivers/net/ethernet/marvell/mvmdio.c
> > index 7354960b583b..a6f59831fc5b 100644
> > --- a/drivers/net/ethernet/marvell/mvmdio.c
> > +++ b/drivers/net/ethernet/marvell/mvmdio.c
> > @@ -76,31 +76,29 @@ static int orion_mdio_wait_ready(struct mii_bus 
> > *bus)
> >   {
> >   	struct orion_mdio_dev *dev = bus->priv;
> >   	unsigned long timeout = usecs_to_jiffies(MVMDIO_SMI_TIMEOUT);
> > -	unsigned long end = jiffies + timeout;
> > -	int timedout = 0;
> >
> > -	while (1) {
> > -	        if (orion_mdio_smi_is_done(dev))
> > +	if (dev->err_interrupt > 0) {
> > +		if (wait_event_timeout(dev->smi_busy_wait,
> > +				       orion_mdio_smi_is_done(dev),
> > +				       1 + timeout))
> >   			return 0;
> > -	        else if (timedout)
> > -			break;
> > +	} else {
> > +		unsigned long end = jiffies + timeout;
> >
> > -	        if (dev->err_interrupt <= 0) {
> > -			usleep_range(MVMDIO_SMI_POLL_INTERVAL_MIN,
> > -				     MVMDIO_SMI_POLL_INTERVAL_MAX);
> > +		while (1) {
> > +	        	if (orion_mdio_smi_is_done(dev))
> > +				return 0;
> >
> >   			if (time_is_before_jiffies(end))
> > -				++timedout;
> > -	        } else {
> > -			wait_event_timeout(dev->smi_busy_wait,
> > -				           orion_mdio_smi_is_done(dev),
> > -				           timeout);
> > -
> > -			++timedout;
> > -	        }
> > +				break;
> > +
> > +			usleep_range(MVMDIO_SMI_POLL_INTERVAL_MIN,
> > +				     MVMDIO_SMI_POLL_INTERVAL_MAX);
> > +		}
> >   	}
> >
> >   	dev_err(bus->parent, "Timeout: SMI busy for too long\n");
> > +
> >   	return  -ETIMEDOUT;
> >   }
>
> Hi Russell,
>
> I did not find any commit for this in 3.13-rc4.
>
> Would you prefer I submit my attempt at refactoring the
> orion_mdio_wait_ready() code ?

I prefer this patch (which I think you originally proposed) because it 
is just as
correct and the code size is a bit smaller in arm mode, and the same 
size in thumb
mode (on my compiler gcc 4.7.2, at least).  I coded the loop in that way 
to make it
small.

I don't mind submitting it to David as I made the mistake in the first 
place.

Regards,

Leigh.

diff --git a/drivers/net/ethernet/marvell/mvmdio.c 
b/drivers/net/ethernet/marvell/mvmdio.c
index 7354960..a42a750 100644
--- a/drivers/net/ethernet/marvell/mvmdio.c
+++ b/drivers/net/ethernet/marvell/mvmdio.c
@@ -92,6 +92,12 @@ static int orion_mdio_wait_ready(struct mii_bus *bus)
 			if (time_is_before_jiffies(end))
 				++timedout;
 	        } else {
+			/* wait_event_timeout does not guarantee a delay of at
+			 * least one whole jiffie, so timeout must be no less
+			 * than two.
+			 */
+			 if (timeout < 2)
+			 	timeout = 2;
 			wait_event_timeout(dev->smi_busy_wait,
 				           orion_mdio_smi_is_done(dev),
 				           timeout);

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