From: Joel Stanley <joel@jms.id.au>
To: Guenter Roeck <linux@roeck-us.net>
Cc: linux-fsi@lists.ozlabs.org, Joachim Fenkes <fenkes@de.ibm.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Alistar Popple <alistair@popple.id.au>
Subject: Re: [PATCH 2/2] fsi/sbefifo: Fix reset timeout
Date: Thu, 10 Sep 2020 03:08:04 +0000 [thread overview]
Message-ID: <CACPK8XcnyO+T18W0pk6dRahg1aanaJYsVfxtXtZN31phub+=TQ@mail.gmail.com> (raw)
In-Reply-To: <d5722caa-cf98-15c4-2e45-9c569ca959b3@roeck-us.net>
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
prev parent reply other threads:[~2020-09-10 3:09 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-24 7:15 [PATCH 0/2] fsi: SBE FIFO fixes Joel Stanley
2020-07-24 7:15 ` [PATCH 1/2] fsi/sbefifo: Clean up correct FIFO when receiving reset request from SBE Joel Stanley
2020-07-27 5:51 ` Benjamin Herrenschmidt
2020-09-10 3:08 ` Joel Stanley
2020-07-24 7:15 ` [PATCH 2/2] fsi/sbefifo: Fix reset timeout Joel Stanley
2020-07-24 14:34 ` Guenter Roeck
2020-09-10 3:08 ` Joel Stanley [this message]
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