Messages in this thread | | | Subject | Re: [PATCH] soc: qcom: rpmh-rsc: Don't use ktime for timeout in write_tcs_reg_sync() | From | Maulik Shah <> | Date | Wed, 24 Jun 2020 10:11:52 +0530 |
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Reviewed-by: Maulik Shah <mkshah@codeaurora.org>
Thanks, Maulik
On 5/28/2020 8:18 PM, Douglas Anderson wrote: > The write_tcs_reg_sync() may be called after timekeeping is suspended > so it's not OK to use ktime. The readl_poll_timeout_atomic() macro > implicitly uses ktime. This was causing a warning at suspend time. > > Change to just loop 1000000 times with a delay of 1 us between loops. > This may give a timeout of more than 1 second but never less and is > safe even if timekeeping is suspended. > > NOTE: I don't have any actual evidence that we need to loop here. > It's possibly that all we really need to do is just read the value > back to ensure that the pipes are cleaned and the looping/comparing is > totally not needed. I never saw the loop being needed in my tests. > However, the loop shouldn't hurt. > > Fixes: 91160150aba0 ("soc: qcom: rpmh-rsc: Timeout after 1 second in write_tcs_reg_sync()") > Reported-by: Maulik Shah <mkshah@codeaurora.org> > Signed-off-by: Douglas Anderson <dianders@chromium.org> > --- > > drivers/soc/qcom/rpmh-rsc.c | 18 +++++++++++++----- > 1 file changed, 13 insertions(+), 5 deletions(-) > > diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c > index 076fd27f3081..906778e2c1fa 100644 > --- a/drivers/soc/qcom/rpmh-rsc.c > +++ b/drivers/soc/qcom/rpmh-rsc.c > @@ -175,13 +175,21 @@ static void write_tcs_reg(const struct rsc_drv *drv, int reg, int tcs_id, > static void write_tcs_reg_sync(const struct rsc_drv *drv, int reg, int tcs_id, > u32 data) > { > - u32 new_data; > + int i; > > writel(data, tcs_reg_addr(drv, reg, tcs_id)); > - if (readl_poll_timeout_atomic(tcs_reg_addr(drv, reg, tcs_id), new_data, > - new_data == data, 1, USEC_PER_SEC)) > - pr_err("%s: error writing %#x to %d:%#x\n", drv->name, > - data, tcs_id, reg); > + > + /* > + * Wait until we read back the same value. Use a counter rather than > + * ktime for timeout since this may be called after timekeeping stops. > + */ > + for (i = 0; i < USEC_PER_SEC; i++) { > + if (readl(tcs_reg_addr(drv, reg, tcs_id)) == data) > + return; > + udelay(1); > + } > + pr_err("%s: error writing %#x to %d:%#x\n", drv->name, > + data, tcs_id, reg); > } > > /**
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