| Message ID | 20240904132842.559217-1-vadim.fedorenko@linux.dev (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next] ptp: ocp: Improve PCIe delay estimation | expand |
On Wed, Sep 04, 2024 at 01:28:42PM +0000, Vadim Fedorenko wrote: > The PCIe bus can be pretty busy during boot and probe function can > see excessive delays. Let's find the minimal value out of several > tests and use it as estimated value. > > Signed-off-by: Vadim Fedorenko <vadim.fedorenko@linux.dev> > --- > drivers/ptp/ptp_ocp.c | 17 ++++++++++------- > 1 file changed, 10 insertions(+), 7 deletions(-) > > diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c > index e7479b9b90cb..22b22e605781 100644 > --- a/drivers/ptp/ptp_ocp.c > +++ b/drivers/ptp/ptp_ocp.c > @@ -1561,19 +1561,22 @@ ptp_ocp_estimate_pci_timing(struct ptp_ocp *bp) > ktime_t start, end; > ktime_t delay; > u32 ctrl; > + int i; > > - ctrl = ioread32(&bp->reg->ctrl); > - ctrl = OCP_CTRL_READ_TIME_REQ | OCP_CTRL_ENABLE; > + for (i = 0; i < 3; i++) { > + ctrl = ioread32(&bp->reg->ctrl); > + ctrl = OCP_CTRL_READ_TIME_REQ | OCP_CTRL_ENABLE; > > - iowrite32(ctrl, &bp->reg->ctrl); > + iowrite32(ctrl, &bp->reg->ctrl); > > - start = ktime_get_ns(); > + start = ktime_get_ns(); > > - ctrl = ioread32(&bp->reg->ctrl); > + ctrl = ioread32(&bp->reg->ctrl); > > - end = ktime_get_ns(); > + end = ktime_get_ns(); > > - delay = end - start; > + delay = min(delay, end - start); Hi Vadim, It looks like delay is used uninitialised here in the first iteration of this loop. Flagged by Smatch. > + } > bp->ts_window_adjust = (delay >> 5) * 3; > } > > -- > 2.43.0 > >
On 04/09/2024 21:20, Simon Horman wrote: > On Wed, Sep 04, 2024 at 01:28:42PM +0000, Vadim Fedorenko wrote: >> The PCIe bus can be pretty busy during boot and probe function can >> see excessive delays. Let's find the minimal value out of several >> tests and use it as estimated value. >> >> Signed-off-by: Vadim Fedorenko <vadim.fedorenko@linux.dev> >> --- >> drivers/ptp/ptp_ocp.c | 17 ++++++++++------- >> 1 file changed, 10 insertions(+), 7 deletions(-) >> >> diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c >> index e7479b9b90cb..22b22e605781 100644 >> --- a/drivers/ptp/ptp_ocp.c >> +++ b/drivers/ptp/ptp_ocp.c >> @@ -1561,19 +1561,22 @@ ptp_ocp_estimate_pci_timing(struct ptp_ocp *bp) >> ktime_t start, end; >> ktime_t delay; >> u32 ctrl; >> + int i; >> >> - ctrl = ioread32(&bp->reg->ctrl); >> - ctrl = OCP_CTRL_READ_TIME_REQ | OCP_CTRL_ENABLE; >> + for (i = 0; i < 3; i++) { >> + ctrl = ioread32(&bp->reg->ctrl); >> + ctrl = OCP_CTRL_READ_TIME_REQ | OCP_CTRL_ENABLE; >> >> - iowrite32(ctrl, &bp->reg->ctrl); >> + iowrite32(ctrl, &bp->reg->ctrl); >> >> - start = ktime_get_ns(); >> + start = ktime_get_ns(); >> >> - ctrl = ioread32(&bp->reg->ctrl); >> + ctrl = ioread32(&bp->reg->ctrl); >> >> - end = ktime_get_ns(); >> + end = ktime_get_ns(); >> >> - delay = end - start; >> + delay = min(delay, end - start); > > Hi Vadim, > > It looks like delay is used uninitialised here > in the first iteration of this loop. > > Flagged by Smatch. Oh, yes, you are right, Simon. I'll send v2 with INT_MAX init for delay. Thanks! > >> + } >> bp->ts_window_adjust = (delay >> 5) * 3; >> } >> >> -- >> 2.43.0 >> >>
diff --git a/drivers/ptp/ptp_ocp.c b/drivers/ptp/ptp_ocp.c index e7479b9b90cb..22b22e605781 100644 --- a/drivers/ptp/ptp_ocp.c +++ b/drivers/ptp/ptp_ocp.c @@ -1561,19 +1561,22 @@ ptp_ocp_estimate_pci_timing(struct ptp_ocp *bp) ktime_t start, end; ktime_t delay; u32 ctrl; + int i; - ctrl = ioread32(&bp->reg->ctrl); - ctrl = OCP_CTRL_READ_TIME_REQ | OCP_CTRL_ENABLE; + for (i = 0; i < 3; i++) { + ctrl = ioread32(&bp->reg->ctrl); + ctrl = OCP_CTRL_READ_TIME_REQ | OCP_CTRL_ENABLE; - iowrite32(ctrl, &bp->reg->ctrl); + iowrite32(ctrl, &bp->reg->ctrl); - start = ktime_get_ns(); + start = ktime_get_ns(); - ctrl = ioread32(&bp->reg->ctrl); + ctrl = ioread32(&bp->reg->ctrl); - end = ktime_get_ns(); + end = ktime_get_ns(); - delay = end - start; + delay = min(delay, end - start); + } bp->ts_window_adjust = (delay >> 5) * 3; }
The PCIe bus can be pretty busy during boot and probe function can see excessive delays. Let's find the minimal value out of several tests and use it as estimated value. Signed-off-by: Vadim Fedorenko <vadim.fedorenko@linux.dev> --- drivers/ptp/ptp_ocp.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-)