diff mbox series

[2/2] fsi/sbefifo: Fix reset timeout

Message ID 20200724071518.430515-3-joel@jms.id.au
State New
Headers show
Series fsi: SBE FIFO fixes | expand

Commit Message

Joel Stanley July 24, 2020, 7:15 a.m. UTC
From: Joachim Fenkes <FENKES@de.ibm.com>

On BMCs with lower timer resolution than 1ms, msleep(1) will take
way longer than 1ms, so looping 10k times won't wait for 10s but
significantly longer.

Fix this by using jiffies like the rest of the code.

Fixes: 9f4a8a2d7f9d ("fsi/sbefifo: Add driver for the SBE FIFO")
Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
Signed-off-by: Joel Stanley <joel@jms.id.au>
---
 drivers/fsi/fsi-sbefifo.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

Comments

Guenter Roeck July 24, 2020, 2:34 p.m. UTC | #1
On 7/24/20 12:15 AM, Joel Stanley wrote:
> From: Joachim Fenkes <FENKES@de.ibm.com>
> 
> On BMCs with lower timer resolution than 1ms, msleep(1) will take
> way longer than 1ms, so looping 10k times won't wait for 10s but
> significantly longer.
> 
> Fix this by using jiffies like the rest of the code.
> 
> Fixes: 9f4a8a2d7f9d ("fsi/sbefifo: Add driver for the SBE FIFO")
> Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
> Signed-off-by: Joel Stanley <joel@jms.id.au>
> ---
>  drivers/fsi/fsi-sbefifo.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/fsi/fsi-sbefifo.c b/drivers/fsi/fsi-sbefifo.c
> index 655b45c1f6ba..3ad9510ad4a4 100644
> --- a/drivers/fsi/fsi-sbefifo.c
> +++ b/drivers/fsi/fsi-sbefifo.c
> @@ -325,6 +325,7 @@ static int sbefifo_up_write(struct sbefifo *sbefifo, __be32 word)
>  static int sbefifo_request_reset(struct sbefifo *sbefifo)
>  {
>  	struct device *dev = &sbefifo->fsi_dev->dev;
> +	unsigned long end_time;
>  	u32 status, timeout;
>  	int rc;
>  
> @@ -341,7 +342,8 @@ static int sbefifo_request_reset(struct sbefifo *sbefifo)
>  	}
>  
>  	/* Wait for it to complete */
> -	for (timeout = 0; timeout < SBEFIFO_RESET_TIMEOUT; timeout++) {
> +	end_time = jiffies + msecs_to_jiffies(SBEFIFO_RESET_TIMEOUT);
> +	while (!time_after(jiffies, end_time)) {
>  		rc = sbefifo_regr(sbefifo, SBEFIFO_UP | SBEFIFO_STS, &status);
>  		if (rc) {
>  			dev_err(dev, "Failed to read UP fifo status during reset"
> @@ -355,7 +357,7 @@ static int sbefifo_request_reset(struct sbefifo *sbefifo)
>  			return 0;
>  		}
>  
> -		msleep(1);
> +		cond_resched();

A hot loop ? Are you sure ? usleep_range() might make more sense here.

Thanks,
Guenter

>  	}
>  	dev_err(dev, "FIFO reset timed out\n");
>  
>
Joel Stanley Sept. 10, 2020, 3:08 a.m. UTC | #2
On Fri, 24 Jul 2020 at 14:34, Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 7/24/20 12:15 AM, Joel Stanley wrote:
> > From: Joachim Fenkes <FENKES@de.ibm.com>
> >
> > On BMCs with lower timer resolution than 1ms, msleep(1) will take
> > way longer than 1ms, so looping 10k times won't wait for 10s but
> > significantly longer.
> >
> > Fix this by using jiffies like the rest of the code.
> >
> > Fixes: 9f4a8a2d7f9d ("fsi/sbefifo: Add driver for the SBE FIFO")
> > Signed-off-by: Joachim Fenkes <fenkes@de.ibm.com>
> > Signed-off-by: Joel Stanley <joel@jms.id.au>
> > ---
> >  drivers/fsi/fsi-sbefifo.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/fsi/fsi-sbefifo.c b/drivers/fsi/fsi-sbefifo.c
> > index 655b45c1f6ba..3ad9510ad4a4 100644
> > --- a/drivers/fsi/fsi-sbefifo.c
> > +++ b/drivers/fsi/fsi-sbefifo.c
> > @@ -325,6 +325,7 @@ static int sbefifo_up_write(struct sbefifo *sbefifo, __be32 word)
> >  static int sbefifo_request_reset(struct sbefifo *sbefifo)
> >  {
> >       struct device *dev = &sbefifo->fsi_dev->dev;
> > +     unsigned long end_time;
> >       u32 status, timeout;
> >       int rc;
> >
> > @@ -341,7 +342,8 @@ static int sbefifo_request_reset(struct sbefifo *sbefifo)
> >       }
> >
> >       /* Wait for it to complete */
> > -     for (timeout = 0; timeout < SBEFIFO_RESET_TIMEOUT; timeout++) {
> > +     end_time = jiffies + msecs_to_jiffies(SBEFIFO_RESET_TIMEOUT);
> > +     while (!time_after(jiffies, end_time)) {
> >               rc = sbefifo_regr(sbefifo, SBEFIFO_UP | SBEFIFO_STS, &status);
> >               if (rc) {
> >                       dev_err(dev, "Failed to read UP fifo status during reset"
> > @@ -355,7 +357,7 @@ static int sbefifo_request_reset(struct sbefifo *sbefifo)
> >                       return 0;
> >               }
> >
> > -             msleep(1);
> > +             cond_resched();
>
> A hot loop ? Are you sure ? usleep_range() might make more sense here.

Thanks for the review.

Joachim, I can fix this up for you.

Do you have a suggestion for how long to wait? What's the best case
completion time for a sbe reset?

We also have a hot loop in sbefifo_wait. I'm open to suggestions for
how long that should delay for.

Cheers,

Joel
diff mbox series

Patch

diff --git a/drivers/fsi/fsi-sbefifo.c b/drivers/fsi/fsi-sbefifo.c
index 655b45c1f6ba..3ad9510ad4a4 100644
--- a/drivers/fsi/fsi-sbefifo.c
+++ b/drivers/fsi/fsi-sbefifo.c
@@ -325,6 +325,7 @@  static int sbefifo_up_write(struct sbefifo *sbefifo, __be32 word)
 static int sbefifo_request_reset(struct sbefifo *sbefifo)
 {
 	struct device *dev = &sbefifo->fsi_dev->dev;
+	unsigned long end_time;
 	u32 status, timeout;
 	int rc;
 
@@ -341,7 +342,8 @@  static int sbefifo_request_reset(struct sbefifo *sbefifo)
 	}
 
 	/* Wait for it to complete */
-	for (timeout = 0; timeout < SBEFIFO_RESET_TIMEOUT; timeout++) {
+	end_time = jiffies + msecs_to_jiffies(SBEFIFO_RESET_TIMEOUT);
+	while (!time_after(jiffies, end_time)) {
 		rc = sbefifo_regr(sbefifo, SBEFIFO_UP | SBEFIFO_STS, &status);
 		if (rc) {
 			dev_err(dev, "Failed to read UP fifo status during reset"
@@ -355,7 +357,7 @@  static int sbefifo_request_reset(struct sbefifo *sbefifo)
 			return 0;
 		}
 
-		msleep(1);
+		cond_resched();
 	}
 	dev_err(dev, "FIFO reset timed out\n");