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    SubjectRe: [PATCH v2 net-next 4/4] time64.h: consolidate uses of PSEC_PER_NSEC


    On 6/28/22 15:52, Vladimir Oltean wrote:
    > Time-sensitive networking code needs to work with PTP times expressed in
    > nanoseconds, and with packet transmission times expressed in
    > picoseconds, since those would be fractional at higher than gigabit
    > speed when expressed in nanoseconds.
    >
    > Convert the existing uses in tc-taprio and the ocelot/felix DSA driver
    > to a PSEC_PER_NSEC macro. This macro is placed in include/linux/time64.h
    > as opposed to its relatives (PSEC_PER_SEC etc) from include/vdso/time64.h
    > because the vDSO library does not (yet) need/use it.
    >
    > Cc: Andy Lutomirski <luto@kernel.org>
    > Cc: Thomas Gleixner <tglx@linutronix.de>
    > Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
    > Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

    Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> # for the vDSO parts

    > ---
    > v1->v2:
    > - move PSEC_PER_NSEC to include/linux/time64.h
    > - add missing include of linux/time.h
    >
    > drivers/net/dsa/ocelot/felix_vsc9959.c | 5 +++--
    > include/linux/time64.h | 3 +++
    > net/sched/sch_taprio.c | 5 +++--
    > 3 files changed, 9 insertions(+), 4 deletions(-)
    >
    > diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
    > index 27d8b56cc21c..28bd4892c30a 100644
    > --- a/drivers/net/dsa/ocelot/felix_vsc9959.c
    > +++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
    > @@ -16,6 +16,7 @@
    > #include <linux/iopoll.h>
    > #include <linux/mdio.h>
    > #include <linux/pci.h>
    > +#include <linux/time.h>
    > #include "felix.h"
    >
    > #define VSC9959_NUM_PORTS 6
    > @@ -1235,7 +1236,7 @@ static void vsc9959_tas_guard_bands_update(struct ocelot *ocelot, int port)
    > u32 max_sdu;
    >
    > if (min_gate_len[tc] == U64_MAX /* Gate always open */ ||
    > - min_gate_len[tc] * 1000 > needed_bit_time_ps) {
    > + min_gate_len[tc] * PSEC_PER_NSEC > needed_bit_time_ps) {
    > /* Setting QMAXSDU_CFG to 0 disables oversized frame
    > * dropping.
    > */
    > @@ -1249,7 +1250,7 @@ static void vsc9959_tas_guard_bands_update(struct ocelot *ocelot, int port)
    > * frame, make sure to enable oversize frame dropping
    > * for frames larger than the smallest that would fit.
    > */
    > - max_sdu = div_u64(min_gate_len[tc] * 1000,
    > + max_sdu = div_u64(min_gate_len[tc] * PSEC_PER_NSEC,
    > picos_per_byte);
    > /* A TC gate may be completely closed, which is a
    > * special case where all packets are oversized.
    > diff --git a/include/linux/time64.h b/include/linux/time64.h
    > index 81b9686a2079..2fb8232cff1d 100644
    > --- a/include/linux/time64.h
    > +++ b/include/linux/time64.h
    > @@ -20,6 +20,9 @@ struct itimerspec64 {
    > struct timespec64 it_value;
    > };
    >
    > +/* Parameters used to convert the timespec values: */
    > +#define PSEC_PER_NSEC 1000L
    > +
    > /* Located here for timespec[64]_valid_strict */
    > #define TIME64_MAX ((s64)~((u64)1 << 63))
    > #define TIME64_MIN (-TIME64_MAX - 1)
    > diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
    > index b9c71a304d39..0b941dd63d26 100644
    > --- a/net/sched/sch_taprio.c
    > +++ b/net/sched/sch_taprio.c
    > @@ -18,6 +18,7 @@
    > #include <linux/module.h>
    > #include <linux/spinlock.h>
    > #include <linux/rcupdate.h>
    > +#include <linux/time.h>
    > #include <net/netlink.h>
    > #include <net/pkt_sched.h>
    > #include <net/pkt_cls.h>
    > @@ -176,7 +177,7 @@ static ktime_t get_interval_end_time(struct sched_gate_list *sched,
    >
    > static int length_to_duration(struct taprio_sched *q, int len)
    > {
    > - return div_u64(len * atomic64_read(&q->picos_per_byte), 1000);
    > + return div_u64(len * atomic64_read(&q->picos_per_byte), PSEC_PER_NSEC);
    > }
    >
    > /* Returns the entry corresponding to next available interval. If
    > @@ -551,7 +552,7 @@ static struct sk_buff *taprio_peek(struct Qdisc *sch)
    > static void taprio_set_budget(struct taprio_sched *q, struct sched_entry *entry)
    > {
    > atomic_set(&entry->budget,
    > - div64_u64((u64)entry->interval * 1000,
    > + div64_u64((u64)entry->interval * PSEC_PER_NSEC,
    > atomic64_read(&q->picos_per_byte)));
    > }
    >

    --
    Regards,
    Vincenzo

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