From: Nikhil Gupta <[email protected]>
1588 driver loses about 1us in adjtime operation at PTP slave.
This is because adjtime operation uses a slow non-atomic tmr_cnt_read()
followed by tmr_cnt_write() operation.
In the above sequence, since the timer counter operation loses about 1us.
Instead, tmr_offset register should be programmed with the delta
nanoseconds This won't lead to timer counter stopping and losing time
while tmr_cnt_write() is being done.
This Patch adds api for tmr_offset_read/write to program the
delta nanoseconds in the Timer offset Register.
Signed-off-by: Nikhil Gupta <[email protected]>
Reviewed-by: Yangbo Lu <[email protected]>
---
drivers/ptp/ptp_qoriq.c | 36 ++++++++++++++++++++++++++++++------
1 file changed, 30 insertions(+), 6 deletions(-)
diff --git a/drivers/ptp/ptp_qoriq.c b/drivers/ptp/ptp_qoriq.c
index 08f4cf0ad9e3..5b6ea6d590be 100644
--- a/drivers/ptp/ptp_qoriq.c
+++ b/drivers/ptp/ptp_qoriq.c
@@ -48,6 +48,29 @@ static void tmr_cnt_write(struct ptp_qoriq *ptp_qoriq, u64 ns)
ptp_qoriq->write(®s->ctrl_regs->tmr_cnt_h, hi);
}
+static void tmr_offset_write(struct ptp_qoriq *ptp_qoriq, u64 delta_ns)
+{
+ struct ptp_qoriq_registers *regs = &ptp_qoriq->regs;
+ u32 hi = delta_ns >> 32;
+ u32 lo = delta_ns & 0xffffffff;
+
+ ptp_qoriq->write(®s->ctrl_regs->tmroff_l, lo);
+ ptp_qoriq->write(®s->ctrl_regs->tmroff_h, hi);
+}
+
+static u64 tmr_offset_read(struct ptp_qoriq *ptp_qoriq)
+{
+ struct ptp_qoriq_registers *regs = &ptp_qoriq->regs;
+ u64 ns;
+ u32 lo, hi;
+
+ lo = ptp_qoriq->read(®s->ctrl_regs->tmroff_l);
+ hi = ptp_qoriq->read(®s->ctrl_regs->tmroff_h);
+ ns = ((u64) hi) << 32;
+ ns |= lo;
+ return ns;
+}
+
/* Caller must hold ptp_qoriq->lock. */
static void set_alarm(struct ptp_qoriq *ptp_qoriq)
{
@@ -55,7 +78,9 @@ static void set_alarm(struct ptp_qoriq *ptp_qoriq)
u64 ns;
u32 lo, hi;
- ns = tmr_cnt_read(ptp_qoriq) + 1500000000ULL;
+ ns = tmr_cnt_read(ptp_qoriq) + tmr_offset_read(ptp_qoriq)
+ + 1500000000ULL;
+
ns = div_u64(ns, 1000000000UL) * 1000000000ULL;
ns -= ptp_qoriq->tclk_period;
hi = ns >> 32;
@@ -207,15 +232,12 @@ EXPORT_SYMBOL_GPL(ptp_qoriq_adjfine);
int ptp_qoriq_adjtime(struct ptp_clock_info *ptp, s64 delta)
{
- s64 now;
unsigned long flags;
struct ptp_qoriq *ptp_qoriq = container_of(ptp, struct ptp_qoriq, caps);
spin_lock_irqsave(&ptp_qoriq->lock, flags);
- now = tmr_cnt_read(ptp_qoriq);
- now += delta;
- tmr_cnt_write(ptp_qoriq, now);
+ tmr_offset_write(ptp_qoriq, delta);
set_fipers(ptp_qoriq);
spin_unlock_irqrestore(&ptp_qoriq->lock, flags);
@@ -232,7 +254,7 @@ int ptp_qoriq_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
spin_lock_irqsave(&ptp_qoriq->lock, flags);
- ns = tmr_cnt_read(ptp_qoriq);
+ ns = tmr_cnt_read(ptp_qoriq) + tmr_offset_read(ptp_qoriq);
spin_unlock_irqrestore(&ptp_qoriq->lock, flags);
@@ -251,6 +273,8 @@ int ptp_qoriq_settime(struct ptp_clock_info *ptp,
ns = timespec64_to_ns(ts);
+ tmr_offset_write(ptp_qoriq, 0);
+
spin_lock_irqsave(&ptp_qoriq->lock, flags);
tmr_cnt_write(ptp_qoriq, ns);
--
2.17.1
++ Richard Cochran
-----Original Message-----
From: [email protected] <[email protected]>
Sent: Tuesday, January 10, 2023 5:00 PM
To: [email protected]; Y.B. Lu <[email protected]>; [email protected]; [email protected]
Cc: Vakul Garg <[email protected]>; Rajan Gupta <[email protected]>; Nikhil Gupta <[email protected]>
Subject: [PATCH] ptp_qoriq: fix latency in ptp_qoriq_adjtime() operation.
From: Nikhil Gupta <[email protected]>
1588 driver loses about 1us in adjtime operation at PTP slave.
This is because adjtime operation uses a slow non-atomic tmr_cnt_read() followed by tmr_cnt_write() operation.
In the above sequence, since the timer counter operation loses about 1us.
Instead, tmr_offset register should be programmed with the delta nanoseconds This won't lead to timer counter stopping and losing time while tmr_cnt_write() is being done.
This Patch adds api for tmr_offset_read/write to program the delta nanoseconds in the Timer offset Register.
Signed-off-by: Nikhil Gupta <[email protected]>
Reviewed-by: Yangbo Lu <[email protected]>
---
drivers/ptp/ptp_qoriq.c | 36 ++++++++++++++++++++++++++++++------
1 file changed, 30 insertions(+), 6 deletions(-)
diff --git a/drivers/ptp/ptp_qoriq.c b/drivers/ptp/ptp_qoriq.c index 08f4cf0ad9e3..5b6ea6d590be 100644
--- a/drivers/ptp/ptp_qoriq.c
+++ b/drivers/ptp/ptp_qoriq.c
@@ -48,6 +48,29 @@ static void tmr_cnt_write(struct ptp_qoriq *ptp_qoriq, u64 ns)
ptp_qoriq->write(®s->ctrl_regs->tmr_cnt_h, hi); }
+static void tmr_offset_write(struct ptp_qoriq *ptp_qoriq, u64 delta_ns)
+{
+ struct ptp_qoriq_registers *regs = &ptp_qoriq->regs;
+ u32 hi = delta_ns >> 32;
+ u32 lo = delta_ns & 0xffffffff;
+
+ ptp_qoriq->write(®s->ctrl_regs->tmroff_l, lo);
+ ptp_qoriq->write(®s->ctrl_regs->tmroff_h, hi); }
+
+static u64 tmr_offset_read(struct ptp_qoriq *ptp_qoriq) {
+ struct ptp_qoriq_registers *regs = &ptp_qoriq->regs;
+ u64 ns;
+ u32 lo, hi;
+
+ lo = ptp_qoriq->read(®s->ctrl_regs->tmroff_l);
+ hi = ptp_qoriq->read(®s->ctrl_regs->tmroff_h);
+ ns = ((u64) hi) << 32;
+ ns |= lo;
+ return ns;
+}
+
/* Caller must hold ptp_qoriq->lock. */ static void set_alarm(struct ptp_qoriq *ptp_qoriq) { @@ -55,7 +78,9 @@ static void set_alarm(struct ptp_qoriq *ptp_qoriq)
u64 ns;
u32 lo, hi;
- ns = tmr_cnt_read(ptp_qoriq) + 1500000000ULL;
+ ns = tmr_cnt_read(ptp_qoriq) + tmr_offset_read(ptp_qoriq)
+ + 1500000000ULL;
+
ns = div_u64(ns, 1000000000UL) * 1000000000ULL;
ns -= ptp_qoriq->tclk_period;
hi = ns >> 32;
@@ -207,15 +232,12 @@ EXPORT_SYMBOL_GPL(ptp_qoriq_adjfine);
int ptp_qoriq_adjtime(struct ptp_clock_info *ptp, s64 delta) {
- s64 now;
unsigned long flags;
struct ptp_qoriq *ptp_qoriq = container_of(ptp, struct ptp_qoriq, caps);
spin_lock_irqsave(&ptp_qoriq->lock, flags);
- now = tmr_cnt_read(ptp_qoriq);
- now += delta;
- tmr_cnt_write(ptp_qoriq, now);
+ tmr_offset_write(ptp_qoriq, delta);
set_fipers(ptp_qoriq);
spin_unlock_irqrestore(&ptp_qoriq->lock, flags); @@ -232,7 +254,7 @@ int ptp_qoriq_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
spin_lock_irqsave(&ptp_qoriq->lock, flags);
- ns = tmr_cnt_read(ptp_qoriq);
+ ns = tmr_cnt_read(ptp_qoriq) + tmr_offset_read(ptp_qoriq);
spin_unlock_irqrestore(&ptp_qoriq->lock, flags);
@@ -251,6 +273,8 @@ int ptp_qoriq_settime(struct ptp_clock_info *ptp,
ns = timespec64_to_ns(ts);
+ tmr_offset_write(ptp_qoriq, 0);
+
spin_lock_irqsave(&ptp_qoriq->lock, flags);
tmr_cnt_write(ptp_qoriq, ns);
--
2.17.1
please put [PATCH net-next] in the subject.
On Tue, 10 Jan 2023 17:00:24 +0530 [email protected] wrote:
> From: Nikhil Gupta <[email protected]>
>
> 1588 driver loses about 1us in adjtime operation at PTP slave.
> This is because adjtime operation uses a slow non-atomic tmr_cnt_read()
> followed by tmr_cnt_write() operation.
So far so good..
> In the above sequence, since the timer counter operation loses about 1us.
s/operation/keeps incrementing after the read/ ?
but frankly I don't think this sentence adds much
> Instead, tmr_offset register should be programmed with the delta
> nanoseconds
missing full stop at the end.
You should describe what the tmr_offset register does.
> This won't lead to timer counter stopping and losing time
> while tmr_cnt_write() is being done.
Stopping? The timer was actually stopping?
> This Patch adds api for tmr_offset_read/write to program the
Use imperative mood.
> delta nanoseconds in the Timer offset Register.
>
> Signed-off-by: Nikhil Gupta <[email protected]>
> Reviewed-by: Yangbo Lu <[email protected]>
> ---
> drivers/ptp/ptp_qoriq.c | 36 ++++++++++++++++++++++++++++++------
> 1 file changed, 30 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/ptp/ptp_qoriq.c b/drivers/ptp/ptp_qoriq.c
> index 08f4cf0ad9e3..5b6ea6d590be 100644
> --- a/drivers/ptp/ptp_qoriq.c
> +++ b/drivers/ptp/ptp_qoriq.c
> @@ -48,6 +48,29 @@ static void tmr_cnt_write(struct ptp_qoriq *ptp_qoriq, u64 ns)
> ptp_qoriq->write(®s->ctrl_regs->tmr_cnt_h, hi);
> }
>
> +static void tmr_offset_write(struct ptp_qoriq *ptp_qoriq, u64 delta_ns)
> +{
> + struct ptp_qoriq_registers *regs = &ptp_qoriq->regs;
> + u32 hi = delta_ns >> 32;
> + u32 lo = delta_ns & 0xffffffff;
> +
> + ptp_qoriq->write(®s->ctrl_regs->tmroff_l, lo);
> + ptp_qoriq->write(®s->ctrl_regs->tmroff_h, hi);
> +}
> +
> +static u64 tmr_offset_read(struct ptp_qoriq *ptp_qoriq)
> +{
> + struct ptp_qoriq_registers *regs = &ptp_qoriq->regs;
> + u64 ns;
> + u32 lo, hi;
Order variable lines longest to shortest
> + lo = ptp_qoriq->read(®s->ctrl_regs->tmroff_l);
> + hi = ptp_qoriq->read(®s->ctrl_regs->tmroff_h);
> + ns = ((u64) hi) << 32;
> + ns |= lo;
> + return ns;
> +}
> +
> /* Caller must hold ptp_qoriq->lock. */
> static void set_alarm(struct ptp_qoriq *ptp_qoriq)
> {
> @@ -55,7 +78,9 @@ static void set_alarm(struct ptp_qoriq *ptp_qoriq)
> u64 ns;
> u32 lo, hi;
>
> - ns = tmr_cnt_read(ptp_qoriq) + 1500000000ULL;
> + ns = tmr_cnt_read(ptp_qoriq) + tmr_offset_read(ptp_qoriq)
> + + 1500000000ULL;
> +
> ns = div_u64(ns, 1000000000UL) * 1000000000ULL;
> ns -= ptp_qoriq->tclk_period;
> hi = ns >> 32;
> @@ -207,15 +232,12 @@ EXPORT_SYMBOL_GPL(ptp_qoriq_adjfine);
>
> int ptp_qoriq_adjtime(struct ptp_clock_info *ptp, s64 delta)
> {
> - s64 now;
> unsigned long flags;
> struct ptp_qoriq *ptp_qoriq = container_of(ptp, struct ptp_qoriq, caps);
>
> spin_lock_irqsave(&ptp_qoriq->lock, flags);
>
> - now = tmr_cnt_read(ptp_qoriq);
> - now += delta;
> - tmr_cnt_write(ptp_qoriq, now);
> + tmr_offset_write(ptp_qoriq, delta);
Writes to the offset register result in an add operation?
Or it's a pure write? What will the offset be after a sequence of
following adjtime() calls:
adjtime(+100);
adjtime(+100);
adjtime(+100);
?
> set_fipers(ptp_qoriq);
>
> spin_unlock_irqrestore(&ptp_qoriq->lock, flags);
> @@ -232,7 +254,7 @@ int ptp_qoriq_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
>
> spin_lock_irqsave(&ptp_qoriq->lock, flags);
>
> - ns = tmr_cnt_read(ptp_qoriq);
> + ns = tmr_cnt_read(ptp_qoriq) + tmr_offset_read(ptp_qoriq);
>
> spin_unlock_irqrestore(&ptp_qoriq->lock, flags);
>
> @@ -251,6 +273,8 @@ int ptp_qoriq_settime(struct ptp_clock_info *ptp,
>
> ns = timespec64_to_ns(ts);
>
> + tmr_offset_write(ptp_qoriq, 0);
Shouldn't this be under the lock?
> spin_lock_irqsave(&ptp_qoriq->lock, flags);
>
> tmr_cnt_write(ptp_qoriq, ns);
-----Original Message-----
From: Jakub Kicinski <[email protected]>
Sent: Thursday, January 12, 2023 10:39 AM
To: Nikhil Gupta <[email protected]>
Cc: [email protected]; Y.B. Lu <[email protected]>; [email protected]; [email protected]; Vakul Garg <[email protected]>; Rajan Gupta <[email protected]>
Subject: [EXT] Re: [PATCH] ptp_qoriq: fix latency in ptp_qoriq_adjtime() operation.
Caution: EXT Email
please put [PATCH net-next] in the subject.
On Tue, 10 Jan 2023 17:00:24 +0530 [email protected] wrote:
> From: Nikhil Gupta <[email protected]>
>
> 1588 driver loses about 1us in adjtime operation at PTP slave.
> This is because adjtime operation uses a slow non-atomic
> tmr_cnt_read() followed by tmr_cnt_write() operation.
So far so good..
> In the above sequence, since the timer counter operation loses about 1us.
s/operation/keeps incrementing after the read/ ?
but frankly I don't think this sentence adds much
> Instead, tmr_offset register should be programmed with the delta
> nanoseconds
missing full stop at the end.
You should describe what the tmr_offset register does.
[Nikhil] : current time is calculated by adding TMROFF_H/L with the timer's counter TMR_CNT_H/L register.
> This won't lead to timer counter stopping and losing time while
> tmr_cnt_write() is being done.
Stopping? The timer was actually stopping?
> This Patch adds api for tmr_offset_read/write to program the
Use imperative mood.
> delta nanoseconds in the Timer offset Register.
>
> Signed-off-by: Nikhil Gupta <[email protected]>
> Reviewed-by: Yangbo Lu <[email protected]>
> ---
> drivers/ptp/ptp_qoriq.c | 36 ++++++++++++++++++++++++++++++------
> 1 file changed, 30 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/ptp/ptp_qoriq.c b/drivers/ptp/ptp_qoriq.c index
> 08f4cf0ad9e3..5b6ea6d590be 100644
> --- a/drivers/ptp/ptp_qoriq.c
> +++ b/drivers/ptp/ptp_qoriq.c
> @@ -48,6 +48,29 @@ static void tmr_cnt_write(struct ptp_qoriq *ptp_qoriq, u64 ns)
> ptp_qoriq->write(®s->ctrl_regs->tmr_cnt_h, hi); }
>
> +static void tmr_offset_write(struct ptp_qoriq *ptp_qoriq, u64
> +delta_ns) {
> + struct ptp_qoriq_registers *regs = &ptp_qoriq->regs;
> + u32 hi = delta_ns >> 32;
> + u32 lo = delta_ns & 0xffffffff;
> +
> + ptp_qoriq->write(®s->ctrl_regs->tmroff_l, lo);
> + ptp_qoriq->write(®s->ctrl_regs->tmroff_h, hi); }
> +
> +static u64 tmr_offset_read(struct ptp_qoriq *ptp_qoriq) {
> + struct ptp_qoriq_registers *regs = &ptp_qoriq->regs;
> + u64 ns;
> + u32 lo, hi;
Order variable lines longest to shortest
> + lo = ptp_qoriq->read(®s->ctrl_regs->tmroff_l);
> + hi = ptp_qoriq->read(®s->ctrl_regs->tmroff_h);
> + ns = ((u64) hi) << 32;
> + ns |= lo;
> + return ns;
> +}
> +
> /* Caller must hold ptp_qoriq->lock. */ static void set_alarm(struct
> ptp_qoriq *ptp_qoriq) { @@ -55,7 +78,9 @@ static void
> set_alarm(struct ptp_qoriq *ptp_qoriq)
> u64 ns;
> u32 lo, hi;
>
> - ns = tmr_cnt_read(ptp_qoriq) + 1500000000ULL;
> + ns = tmr_cnt_read(ptp_qoriq) + tmr_offset_read(ptp_qoriq)
> + + 1500000000ULL;
> +
> ns = div_u64(ns, 1000000000UL) * 1000000000ULL;
> ns -= ptp_qoriq->tclk_period;
> hi = ns >> 32;
> @@ -207,15 +232,12 @@ EXPORT_SYMBOL_GPL(ptp_qoriq_adjfine);
>
> int ptp_qoriq_adjtime(struct ptp_clock_info *ptp, s64 delta) {
> - s64 now;
> unsigned long flags;
> struct ptp_qoriq *ptp_qoriq = container_of(ptp, struct
> ptp_qoriq, caps);
>
> spin_lock_irqsave(&ptp_qoriq->lock, flags);
>
> - now = tmr_cnt_read(ptp_qoriq);
> - now += delta;
> - tmr_cnt_write(ptp_qoriq, now);
> + tmr_offset_write(ptp_qoriq, delta);
Writes to the offset register result in an add operation?
Or it's a pure write? What will the offset be after a sequence of following adjtime() calls:
adjtime(+100);
adjtime(+100);
adjtime(+100);
?
[Nikhil] : It's a pure write operation, I will be sending the updated version of the patch.
Wherein retaining the earlier offset value and adding to the new.
> set_fipers(ptp_qoriq);
>
> spin_unlock_irqrestore(&ptp_qoriq->lock, flags); @@ -232,7
> +254,7 @@ int ptp_qoriq_gettime(struct ptp_clock_info *ptp, struct
> timespec64 *ts)
>
> spin_lock_irqsave(&ptp_qoriq->lock, flags);
>
> - ns = tmr_cnt_read(ptp_qoriq);
> + ns = tmr_cnt_read(ptp_qoriq) + tmr_offset_read(ptp_qoriq);
>
> spin_unlock_irqrestore(&ptp_qoriq->lock, flags);
>
> @@ -251,6 +273,8 @@ int ptp_qoriq_settime(struct ptp_clock_info *ptp,
>
> ns = timespec64_to_ns(ts);
>
> + tmr_offset_write(ptp_qoriq, 0);
Shouldn't this be under the lock?
[Nikhil] : will update this.
> spin_lock_irqsave(&ptp_qoriq->lock, flags);
>
> tmr_cnt_write(ptp_qoriq, ns);