Re: [PATCH v2 1/1] net: fec: ptp: avoid register access when ipg clock is disabled

On Thu, Feb 25, 2021 at 10:15:16PM +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 <redacted>
---
v2:
 - add mutex (thanks to Richard)

v3:
I did a mistake and did not test properly
 - add parenteses
 - fix the used variable

Acked-by: Richard Cochran <richardcochran@gmail.com>