netdev - Re: [RFC PATCH 3/9] net: dsa: hellcreek: Add PTP clock support

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Message-ID: <87366jaagv.fsf@kurt>
Date:   Thu, 25 Jun 2020 09:08:48 +0200
From:   Kurt Kanzenbach <kurt@...utronix.de>
To:     Richard Cochran <richardcochran@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        Rob Herring <robh+dt@...nel.org>, devicetree@...r.kernel.org,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Kamil Alkhouri <kamil.alkhouri@...offenburg.de>,
        ilias.apalodimas@...aro.org
Subject: Re: [RFC PATCH 3/9] net: dsa: hellcreek: Add PTP clock support

Hi Richard,

On Wed Jun 24 2020, Richard Cochran wrote:
> On Thu, Jun 18, 2020 at 08:40:23AM +0200, Kurt Kanzenbach wrote:
>
>> diff --git a/drivers/net/dsa/hirschmann/hellcreek.h b/drivers/net/dsa/hirschmann/hellcreek.h
>> index a08a10cb5ab7..2d4422fd2567 100644
>> --- a/drivers/net/dsa/hirschmann/hellcreek.h
>> +++ b/drivers/net/dsa/hirschmann/hellcreek.h
>> @@ -234,10 +234,17 @@ struct hellcreek_fdb_entry {
>>  struct hellcreek {
>>  	struct device *dev;
>>  	struct dsa_switch *ds;
>> +	struct ptp_clock *ptp_clock;
>> +	struct ptp_clock_info ptp_clock_info;
>>  	struct hellcreek_port ports[4];
>> +	struct delayed_work overflow_work;
>>  	spinlock_t reg_lock;	/* Switch IP register lock */
>> +	spinlock_t ptp_lock;	/* PTP IP register lock */
>
> Why use a spin lock and not a mutex?

No particular reason. Mutex will also work.

>> +	hellcreek->ptp_clock = ptp_clock_register(&hellcreek->ptp_clock_info,
>> +						  hellcreek->dev);
>> +	if (IS_ERR(hellcreek->ptp_clock))
>> +		return PTR_ERR(hellcreek->ptp_clock);
>
> The ptp_clock_register() can also return NULL:
>
>  * Returns a valid pointer on success or PTR_ERR on failure.  If PHC
>  * support is missing at the configuration level, this function
>  * returns NULL, and drivers are expected to gracefully handle that
>  * case separately.
>

I see, thanks. I guess we could add the missing NULL checks to remove()
and get_ts_info() to handle that case gracefully.

Thanks,
Kurt

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