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ptp_qoriq: fix latency in ptp_qoriq_adjtime() operation 

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 keeps
incrementing, it leads to latency. The tmr_offset register
(which is added to TMR_CNT_H/L register giving the current time)
must be programmed with the delta nanoseconds.

Signed-off-by: Nikhil Gupta <nikhil.gupta@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20230119204034.7969-1-nikhil.gupta@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Nikhil Gupta 2023-01-20 02:10:34 +05:30 committed by Jakub Kicinski
parent 5e64f59a3c
commit 24a7fffb25
2 changed files with 44 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

50
drivers/ptp/ptp_qoriq.c
View File

@ -48,6 +48,29 @@ static void tmr_cnt_write(struct ptp_qoriq *ptp_qoriq, u64 ns)
ptp_qoriq->write(&regs->ctrl_regs->tmr_cnt_h, hi);
}
static u64 tmr_offset_read(struct ptp_qoriq *ptp_qoriq)
{
struct ptp_qoriq_registers *regs = &ptp_qoriq->regs;
u32 lo, hi;
u64 ns;
lo = ptp_qoriq->read(&regs->ctrl_regs->tmroff_l);
hi = ptp_qoriq->read(&regs->ctrl_regs->tmroff_h);
ns = ((u64) hi) << 32;
ns |= lo;
return ns;
}
static void tmr_offset_write(struct ptp_qoriq *ptp_qoriq, u64 delta_ns)
{
struct ptp_qoriq_registers *regs = &ptp_qoriq->regs;
u32 lo = delta_ns & 0xffffffff;
u32 hi = delta_ns >> 32;
ptp_qoriq->write(&regs->ctrl_regs->tmroff_l, lo);
ptp_qoriq->write(&regs->ctrl_regs->tmroff_h, hi);
}
/* 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 +232,24 @@ 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);
s64 now, curr_delta;
unsigned long flags;
spin_lock_irqsave(&ptp_qoriq->lock, flags);
now = tmr_cnt_read(ptp_qoriq);
now += delta;
tmr_cnt_write(ptp_qoriq, now);
/* On LS1021A, eTSEC2 and eTSEC3 do not take into account the TMR_OFF
* adjustment
*/
if (ptp_qoriq->etsec) {
now = tmr_cnt_read(ptp_qoriq);
now += delta;
tmr_cnt_write(ptp_qoriq, now);
} else {
curr_delta = tmr_offset_read(ptp_qoriq);
curr_delta += delta;
tmr_offset_write(ptp_qoriq, curr_delta);
}
set_fipers(ptp_qoriq);
spin_unlock_irqrestore(&ptp_qoriq->lock, flags);
@ -232,7 +266,7 @@ 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);
@ -253,6 +287,7 @@ int ptp_qoriq_settime(struct ptp_clock_info *ptp,
spin_lock_irqsave(&ptp_qoriq->lock, flags);
tmr_offset_write(ptp_qoriq, 0);
tmr_cnt_write(ptp_qoriq, ns);
set_fipers(ptp_qoriq);
@ -488,6 +523,7 @@ int ptp_qoriq_init(struct ptp_qoriq *ptp_qoriq, void __iomem *base,
/* The eTSEC uses differnt memory map with DPAA/ENETC */
if (of_device_is_compatible(node, "fsl,etsec-ptp")) {
ptp_qoriq->etsec = true;
ptp_qoriq->regs.ctrl_regs = base + ETSEC_CTRL_REGS_OFFSET;
ptp_qoriq->regs.alarm_regs = base + ETSEC_ALARM_REGS_OFFSET;
ptp_qoriq->regs.fiper_regs = base + ETSEC_FIPER_REGS_OFFSET;

1
include/linux/fsl/ptp_qoriq.h
View File

@ -149,6 +149,7 @@ struct ptp_qoriq {
struct device *dev;
bool extts_fifo_support;
bool fiper3_support;
bool etsec;
int irq;
int phc_index;
u32 tclk_period; /* nanoseconds */