Messages in this thread | | | From | Heiko Thiery <> | Date | Tue, 23 Feb 2021 09:00:32 +0100 | Subject | Re: [PATCH 1/1] net: fec: ptp: avoid register access when ipg clock is disabled |
| |
HI Jakub,
Am Di., 23. Feb. 2021 um 04:00 Uhr schrieb Jakub Kicinski <kuba@kernel.org>: > > On Sat, 20 Feb 2021 07:56:55 +0100 Heiko Thiery wrote: > > When accessing the timecounter register on an i.MX8MQ the kernel hangs. > > This is only the case when the interface is down. This can be reproduced > > by reading with 'phc_ctrl eth0 get'. > > > > Like described in the change in 91c0d987a9788dcc5fe26baafd73bf9242b68900 > > the igp clock is disabled when the interface is down and leads to a > > system hang. > > > > So we check if the ptp clock status before reading the timecounter > > register. > > > > Signed-off-by: Heiko Thiery <heiko.thiery@gmail.com> > > Please widen the CC list, you should CC Richard on PTP patches. > > > diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c > > index 2e344aada4c6..c9882083da02 100644 > > --- a/drivers/net/ethernet/freescale/fec_ptp.c > > +++ b/drivers/net/ethernet/freescale/fec_ptp.c > > @@ -377,6 +377,9 @@ static int fec_ptp_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts) > > u64 ns; > > unsigned long flags; > > > > + /* Check the ptp clock */ > > Comment is rather redundant. Drop it or say _when_ ptp_clk_on may not > be true.
I just used the same comment as the one in the fec_ptp_settime() function.
> > > + if (!adapter->ptp_clk_on) > > + return -EINVAL; > > Why is the PTP interface registered when it can't be accessed? > > Perhaps the driver should unregister the PTP clock when it's brought > down?
Good question, but I do not know what happens e.g. with linuxptp when the device that was opened before will be gone.
Maybe Richard can give a hint.
> > > spin_lock_irqsave(&adapter->tmreg_lock, flags); > > ns = timecounter_read(&adapter->tc); > > spin_unlock_irqrestore(&adapter->tmreg_lock, flags);
-- Heiko
| |