netdev - Re: [PATCH v4 1/1] net: fec: ptp: avoid register access when ipg clock is disabled

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Date:	Thu, 21 Aug 2014 09:02:41 +0200
From:	Richard Cochran <richardcochran@...il.com>
To:	Fugang Duan <b38611@...escale.com>
Cc:	davem@...emloft.net, netdev@...r.kernel.org, shawn.guo@...aro.org
Subject: Re: [PATCH v4 1/1] net: fec: ptp: avoid register access when ipg
 clock is disabled

On Tue, Aug 19, 2014 at 11:20:53AM +0800, Fugang Duan wrote:
> The current kernel hang on i.MX6SX with rootfs mount from MMC.
> The root cause is ptp rise up period timer to access enet register

s/ptp rise up period/that ptp uses a periodic/

> even if ipg clock is disabled.

...

> diff --git a/drivers/net/ethernet/freescale/fec_ptp.c b/drivers/net/ethernet/freescale/fec_ptp.c
> index 82386b2..6d65555 100644
> --- a/drivers/net/ethernet/freescale/fec_ptp.c
> +++ b/drivers/net/ethernet/freescale/fec_ptp.c
> @@ -245,12 +245,18 @@ static int fec_ptp_settime(struct ptp_clock_info *ptp,
>  	u64 ns;
>  	unsigned long flags;
>  
> +	mutex_lock(&fep->ptp_clk_mutex);
> +	/* Check the ptp clock */
> +	if (!fep->ptp_clk_on)
> +		return -EINVAL;

You are still holding the mutex here.

> +
>  	ns = ts->tv_sec * 1000000000ULL;
>  	ns += ts->tv_nsec;
>  
>  	spin_lock_irqsave(&fep->tmreg_lock, flags);
>  	timecounter_init(&fep->tc, &fep->cc, ns);
>  	spin_unlock_irqrestore(&fep->tmreg_lock, flags);
> +	mutex_unlock(&fep->ptp_clk_mutex);
>  	return 0;
>  }

Thanks,
Richard
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