| Message ID | 20200817122415.6568-3-zhukeqian1@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | clocksource: arm_arch_timer: Some fixes and code adjustment | expand |
On 2020-08-17 13:24, Keqian Zhu wrote: > ARM virtual counter supports event stream, it can only trigger an event > when the trigger bit (the value of CNTKCTL_EL1.EVNTI) of CNTVCT_EL0 > changes, > so the actual period of event stream is 2^(cntkctl_evnti + 1). For > example, > when the trigger bit is 0, then virtual counter trigger an event for > every > two cycles. > > Signed-off-by: Marc Zyngier <maz@kernel.org> I have never given you this tag, you are making it up. Please read Documentation/process/submitting-patches.rst to understand what tag you can put by yourself. At best, put "Suggested-by" tag, as this is different from what I posted anyway. Thanks, M. > Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com> > --- > drivers/clocksource/arm_arch_timer.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/drivers/clocksource/arm_arch_timer.c > b/drivers/clocksource/arm_arch_timer.c > index 6e11c60..4140a37 100644 > --- a/drivers/clocksource/arm_arch_timer.c > +++ b/drivers/clocksource/arm_arch_timer.c > @@ -794,10 +794,14 @@ static void arch_timer_configure_evtstream(void) > { > int evt_stream_div, pos; > > - /* Find the closest power of two to the divisor */ > - evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ; > + /* > + * Find the closest power of two to the divisor. As the event > + * stream can at most be generated at half the frequency of the > + * counter, use half the frequency when computing the divider. > + */ > + evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ / 2; > pos = fls(evt_stream_div); > - if (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))) > + if ((pos == 1) || (pos > 1 && !(evt_stream_div & (1 << (pos - 2))))) > pos--; > /* enable event stream */ > arch_timer_evtstrm_enable(min(pos, 15));
Hi Marc, On 2020/8/17 20:56, Marc Zyngier wrote: > On 2020-08-17 13:24, Keqian Zhu wrote: >> ARM virtual counter supports event stream, it can only trigger an event >> when the trigger bit (the value of CNTKCTL_EL1.EVNTI) of CNTVCT_EL0 changes, >> so the actual period of event stream is 2^(cntkctl_evnti + 1). For example, >> when the trigger bit is 0, then virtual counter trigger an event for every >> two cycles. >> >> Signed-off-by: Marc Zyngier <maz@kernel.org> > > I have never given you this tag, you are making it up. Please read > Documentation/process/submitting-patches.rst to understand what > tag you can put by yourself. Sorry about my mistake. > > At best, put "Suggested-by" tag, as this is different from what > I posted anyway. OK, I will use this tag. Thanks, Keqian > > Thanks, > > M. > >> Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com> >> --- >> drivers/clocksource/arm_arch_timer.c | 10 +++++++--- >> 1 file changed, 7 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/clocksource/arm_arch_timer.c >> b/drivers/clocksource/arm_arch_timer.c >> index 6e11c60..4140a37 100644 >> --- a/drivers/clocksource/arm_arch_timer.c >> +++ b/drivers/clocksource/arm_arch_timer.c >> @@ -794,10 +794,14 @@ static void arch_timer_configure_evtstream(void) >> { >> int evt_stream_div, pos; >> >> - /* Find the closest power of two to the divisor */ >> - evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ; >> + /* >> + * Find the closest power of two to the divisor. As the event >> + * stream can at most be generated at half the frequency of the >> + * counter, use half the frequency when computing the divider. >> + */ >> + evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ / 2; >> pos = fls(evt_stream_div); >> - if (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))) >> + if ((pos == 1) || (pos > 1 && !(evt_stream_div & (1 << (pos - 2))))) >> pos--; >> /* enable event stream */ >> arch_timer_evtstrm_enable(min(pos, 15)); >
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 6e11c60..4140a37 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -794,10 +794,14 @@ static void arch_timer_configure_evtstream(void) { int evt_stream_div, pos; - /* Find the closest power of two to the divisor */ - evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ; + /* + * Find the closest power of two to the divisor. As the event + * stream can at most be generated at half the frequency of the + * counter, use half the frequency when computing the divider. + */ + evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ / 2; pos = fls(evt_stream_div); - if (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))) + if ((pos == 1) || (pos > 1 && !(evt_stream_div & (1 << (pos - 2))))) pos--; /* enable event stream */ arch_timer_evtstrm_enable(min(pos, 15));