netdev - RE: [PATCH v3 1/1] net: fec: ptp: avoid register access when ipg clock is disabled

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Date:	Mon, 18 Aug 2014 05:26:18 +0000
From:	"fugang.duan@...escale.com" <fugang.duan@...escale.com>
To:	Richard Cochran <richardcochran@...il.com>
CC:	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"shawn.guo@...aro.org" <shawn.guo@...aro.org>
Subject: RE: [PATCH v3 1/1] net: fec: ptp: avoid register access when ipg
 clock is disabled

From: Richard Cochran <richardcochran@...il.com> Data: Saturday, August 16, 2014 2:09 AM
>To: Duan Fugang-B38611
>Cc: davem@...emloft.net; netdev@...r.kernel.org; shawn.guo@...aro.org
>Subject: Re: [PATCH v3 1/1] net: fec: ptp: avoid register access when ipg
>clock is disabled
>
>Looks better, but ...
>
>On Fri, Aug 15, 2014 at 01:52:55PM +0800, Fugang Duan wrote:
>
>> diff --git a/drivers/net/ethernet/freescale/fec_main.c
>b/drivers/net/ethernet/freescale/fec_main.c
>> index 66fe1f6..ba35994 100644
>> --- a/drivers/net/ethernet/freescale/fec_main.c
>> +++ b/drivers/net/ethernet/freescale/fec_main.c
>> @@ -1613,14 +1613,18 @@ static int fec_enet_clk_enable(struct net_device
>*ndev, bool enable)
>>  			ret = clk_prepare_enable(fep->clk_ptp);
>>  			if (ret)
>>  				goto failed_clk_ptp;
>> +			else
>> +				fep->ptp_clk_on = true;
>>  		}
>>  	} else {
>>  		clk_disable_unprepare(fep->clk_ahb);
>>  		clk_disable_unprepare(fep->clk_ipg);
>>  		if (fep->clk_enet_out)
>>  			clk_disable_unprepare(fep->clk_enet_out);
>> -		if (fep->clk_ptp)
>> +		if (fep->clk_ptp) {
>>  			clk_disable_unprepare(fep->clk_ptp);
>> +			fep->ptp_clk_on = false;
>
>Set the flag to false first, because this races ...	
I will change it. Thanks!
If there have race, so it is better to add mutex to protect the flag ?

>
>> diff --git a/drivers/net/ethernet/freescale/fec_ptp.c
>b/drivers/net/ethernet/freescale/fec_ptp.c
>> index 82386b2..8084aaf 100644
>> --- a/drivers/net/ethernet/freescale/fec_ptp.c
>> +++ b/drivers/net/ethernet/freescale/fec_ptp.c
>> @@ -245,6 +245,10 @@ static int fec_ptp_settime(struct ptp_clock_info
>*ptp,
>>  	u64 ns;
>>  	unsigned long flags;
>>
>> +	/* Check the ptp clock */
>> +	if (!fep->ptp_clk_on)
>> +		return -EINVAL;
>
>with this and ...
>
>> +
>>  	ns = ts->tv_sec * 1000000000ULL;
>>  	ns += ts->tv_nsec;
>>
>> @@ -338,17 +342,20 @@ int fec_ptp_get(struct net_device *ndev, struct
>ifreq *ifr)
>>   * fec_time_keep - call timecounter_read every second to avoid timer
>overrun
>>   *                 because ENET just support 32bit counter, will
>timeout in 4s
>>   */
>> -static void fec_time_keep(unsigned long _data)
>> +static void fec_time_keep(struct work_struct *work)
>>  {
>> -	struct fec_enet_private *fep = (struct fec_enet_private *)_data;
>> +	struct delayed_work *dwork = to_delayed_work(work);
>> +	struct fec_enet_private *fep = container_of(dwork, struct
>fec_enet_private, time_keep);
>>  	u64 ns;
>>  	unsigned long flags;
>>
>> -	spin_lock_irqsave(&fep->tmreg_lock, flags);
>> -	ns = timecounter_read(&fep->tc);
>> -	spin_unlock_irqrestore(&fep->tmreg_lock, flags);
>> +	if (fep->ptp_clk_on) {
>
>with this.
>
>> +		spin_lock_irqsave(&fep->tmreg_lock, flags);
>> +		ns = timecounter_read(&fep->tc);
>> +		spin_unlock_irqrestore(&fep->tmreg_lock, flags);
>> +	}
>
>Thanks,
>Richard
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