change log:
v2:
- Do not revert commit 0ea415390cd3, fix it instead.
- Correct the tags of second patch.
Keqian Zhu (2):
clocksource: arm_arch_timer: Use stable count reader in erratum sne
clocksource: arm_arch_timer: Correct fault programming of
CNTKCTL_EL1.EVNTI
drivers/clocksource/arm_arch_timer.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
--
1.8.3.1
In commit 0ea415390cd3 ("clocksource/arm_arch_timer: Use arch_timer_read_counter
to access stable counters"), we separate stable and normal count reader to omit
unnecessary overhead on systems that have no timer erratum.
However, in erratum_set_next_event_tval_generic(), count reader becomes normal
reader. This converts it to stable reader.
Fixes: 0ea415390cd3 ("clocksource/arm_arch_timer: Use
arch_timer_read_counter to access stable counters")
Signed-off-by: Keqian Zhu <[email protected]>
---
drivers/clocksource/arm_arch_timer.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 6c3e841..777d38c 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -396,10 +396,10 @@ static void erratum_set_next_event_tval_generic(const int access, unsigned long
ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
if (access == ARCH_TIMER_PHYS_ACCESS) {
- cval = evt + arch_counter_get_cntpct();
+ cval = evt + arch_counter_get_cntpct_stable();
write_sysreg(cval, cntp_cval_el0);
} else {
- cval = evt + arch_counter_get_cntvct();
+ cval = evt + arch_counter_get_cntvct_stable();
write_sysreg(cval, cntv_cval_el0);
}
--
1.8.3.1
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.
Fixes: 037f637767a8 ("drivers: clocksource: add support for
ARM architected timer event stream")
Suggested-by: Marc Zyngier <[email protected]>
Signed-off-by: Keqian Zhu <[email protected]>
---
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 777d38c..e3b2ee0 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -824,10 +824,14 @@ 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));
--
1.8.3.1
Hi Marc,
Found that this bugfix series is not applied for now.
Does it need some modification? Wish you can pick it up :-)
Thanks,
Keqian
On 2020/8/18 11:28, Keqian Zhu wrote:
> change log:
>
> v2:
> - Do not revert commit 0ea415390cd3, fix it instead.
> - Correct the tags of second patch.
>
> Keqian Zhu (2):
> clocksource: arm_arch_timer: Use stable count reader in erratum sne
> clocksource: arm_arch_timer: Correct fault programming of
> CNTKCTL_EL1.EVNTI
>
> drivers/clocksource/arm_arch_timer.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
On 2020-08-18 04:28, 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.
>
> Fixes: 037f637767a8 ("drivers: clocksource: add support for
> ARM architected timer event stream")
Fixes: tags should on a single line.
> Suggested-by: Marc Zyngier <[email protected]>
> Signed-off-by: Keqian Zhu <[email protected]>
> ---
> 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 777d38c..e3b2ee0 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -824,10 +824,14 @@ 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--;
You don't explain why you are special-casing pos == 1.
> /* enable event stream */
> arch_timer_evtstrm_enable(min(pos, 15));
Also, please Cc the subsystem maintainers:
CLOCKSOURCE, CLOCKEVENT DRIVERS
M: Daniel Lezcano <[email protected]>
M: Thomas Gleixner <[email protected]>
L: [email protected]
S: Supported
T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
timers/core
F: Documentation/devicetree/bindings/timer/
F: drivers/clocksource/
Thanks,
M.
--
Jazz is not dead. It just smells funny...
On 2020-08-18 04:28, Keqian Zhu wrote:
> In commit 0ea415390cd3 ("clocksource/arm_arch_timer: Use
> arch_timer_read_counter
> to access stable counters"), we separate stable and normal count reader
> to omit
> unnecessary overhead on systems that have no timer erratum.
>
> However, in erratum_set_next_event_tval_generic(), count reader becomes
> normal
> reader. This converts it to stable reader.
>
> Fixes: 0ea415390cd3 ("clocksource/arm_arch_timer: Use
> arch_timer_read_counter to access stable counters")
On a single line.
> Signed-off-by: Keqian Zhu <[email protected]>
> ---
> drivers/clocksource/arm_arch_timer.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/clocksource/arm_arch_timer.c
> b/drivers/clocksource/arm_arch_timer.c
> index 6c3e841..777d38c 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -396,10 +396,10 @@ static void
> erratum_set_next_event_tval_generic(const int access, unsigned long
> ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
>
> if (access == ARCH_TIMER_PHYS_ACCESS) {
> - cval = evt + arch_counter_get_cntpct();
> + cval = evt + arch_counter_get_cntpct_stable();
> write_sysreg(cval, cntp_cval_el0);
> } else {
> - cval = evt + arch_counter_get_cntvct();
> + cval = evt + arch_counter_get_cntvct_stable();
> write_sysreg(cval, cntv_cval_el0);
> }
With that fixed:
Acked-by: Marc Zyngier <[email protected]>
This should go via the clocksource tree.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
Hi Marc,
On 2020/12/3 22:57, Marc Zyngier wrote:
> On 2020-08-18 04:28, 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.
>>
>> Fixes: 037f637767a8 ("drivers: clocksource: add support for
>> ARM architected timer event stream")
>
> Fixes: tags should on a single line.
Will do.
>
>> Suggested-by: Marc Zyngier <[email protected]>
>> Signed-off-by: Keqian Zhu <[email protected]>
>> ---
>> 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 777d38c..e3b2ee0 100644
>> --- a/drivers/clocksource/arm_arch_timer.c
>> +++ b/drivers/clocksource/arm_arch_timer.c
>> @@ -824,10 +824,14 @@ 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--;
>
> You don't explain why you are special-casing pos == 1.
The logic is not clear here, I will try to reform it.
>
>> /* enable event stream */
>> arch_timer_evtstrm_enable(min(pos, 15));
>
> Also, please Cc the subsystem maintainers:
>
> CLOCKSOURCE, CLOCKEVENT DRIVERS
> M: Daniel Lezcano <[email protected]>
> M: Thomas Gleixner <[email protected]>
> L: [email protected]
> S: Supported
> T: git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core
> F: Documentation/devicetree/bindings/timer/
> F: drivers/clocksource/
>
Will do.
> Thanks,
>
> M.
Thanks,
Keqian
Hi Marc,
On 2020/12/3 22:58, Marc Zyngier wrote:
> On 2020-08-18 04:28, Keqian Zhu wrote:
>> In commit 0ea415390cd3 ("clocksource/arm_arch_timer: Use arch_timer_read_counter
>> to access stable counters"), we separate stable and normal count reader to omit
>> unnecessary overhead on systems that have no timer erratum.
>>
>> However, in erratum_set_next_event_tval_generic(), count reader becomes normal
>> reader. This converts it to stable reader.
>>
>> Fixes: 0ea415390cd3 ("clocksource/arm_arch_timer: Use
>> arch_timer_read_counter to access stable counters")
>
> On a single line.
Addressed. Thanks.
>
>> Signed-off-by: Keqian Zhu <[email protected]>
>> ---
>> drivers/clocksource/arm_arch_timer.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/clocksource/arm_arch_timer.c
>> b/drivers/clocksource/arm_arch_timer.c
>> index 6c3e841..777d38c 100644
>> --- a/drivers/clocksource/arm_arch_timer.c
>> +++ b/drivers/clocksource/arm_arch_timer.c
>> @@ -396,10 +396,10 @@ static void
>> erratum_set_next_event_tval_generic(const int access, unsigned long
>> ctrl &= ~ARCH_TIMER_CTRL_IT_MASK;
>>
>> if (access == ARCH_TIMER_PHYS_ACCESS) {
>> - cval = evt + arch_counter_get_cntpct();
>> + cval = evt + arch_counter_get_cntpct_stable();
>> write_sysreg(cval, cntp_cval_el0);
>> } else {
>> - cval = evt + arch_counter_get_cntvct();
>> + cval = evt + arch_counter_get_cntvct_stable();
>> write_sysreg(cval, cntv_cval_el0);
>> }
>
> With that fixed:
>
> Acked-by: Marc Zyngier <[email protected]>
>
> This should go via the clocksource tree.
Added Cc to it's maintainers, thanks.
>
> Thanks,
>
> M.
Cheers,
Keqian