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

Heiko Thiery
2021-02-26T07:24:54Z

Hi all,

Am Do., 25. Feb. 2021 um 22:15 Uhr schrieb Heiko Thiery
<heiko.thiery@gmail.com>:
>
> 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>

Sorry for the noise. But just realized that I sent a v3 version of the
patch but forgot to update the subject line (still v2). Should I
resend it with the correct subject?

> ---
> v2:
> - add mutex (thanks to Richard)
>
> v3:
> I did a mistake and did not test properly
> - add parenteses
> - fix the used variable
>
> drivers/net/ethernet/freescale/fec_ptp.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
> index 2e344aada4c6..1753807cbf97 100644
> --- a/drivers/net/ethernet/freescale/fec_ptp.c
> +++ b/drivers/net/ethernet/freescale/fec_ptp.c
> @@ -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);
>
> --
> 2.30.0
>