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net: fec: ptp: avoid register access when ipg clock is disabled

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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 91c0d987a9
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>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Link: https://lore.kernel.org/r/20210225211514.9115-1-heiko.thiery@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Heiko Thiery 2021-02-25 22:15:16 +01:00 committed by Jakub Kicinski
parent 7f654157f0
commit 6a4d7234ae
1 changed files with 7 additions and 0 deletions
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7
drivers/net/ethernet/freescale/fec_ptp.c
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@ -377,9 +377,16 @@ static int fec_ptp_gettime(struct ptp_clock_info *ptp, struct timespec64 *ts)
u64 ns;
unsigned long flags;
mutex_lock(&adapter->ptp_clk_mutex);
/* Check the ptp clock */
if (!adapter->ptp_clk_on) {
mutex_unlock(&adapter->ptp_clk_mutex);
return -EINVAL;
}
spin_lock_irqsave(&adapter->tmreg_lock, flags);
ns = timecounter_read(&adapter->tc);
spin_unlock_irqrestore(&adapter->tmreg_lock, flags);
mutex_unlock(&adapter->ptp_clk_mutex);
*ts = ns_to_timespec64(ns);