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Date:   Mon, 20 Apr 2020 10:00:51 -0700
From:   Richard Cochran <richardcochran@gmail.com>
To:     Arnd Bergmann <arnd@arndb.de>
Cc:     Clay McClure <clay@daemons.net>,
        Grygorii Strashko <grygorii.strashko@ti.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sekhar Nori <nsekhar@ti.com>,
        Networking <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] net: cpts: Condition WARN_ON on PTP_1588_CLOCK
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On Mon, Apr 20, 2020 at 04:38:32PM +0200, Arnd Bergmann wrote:
> 
> I suspect we should move all of them back. This was an early user
> of 'imply', but the meaning of that keyword has now changed
> in the latest Kconfig.

Can you please explain the justification for changing the meaning?

It was a big PITA for me to support this in the first place, and now
we are back to square one?

> Something else is wrong if you need IS_ERR_OR_NULL(). Any
> kernel interface should either return an negative error code when
> something goes wrong, or should return NULL for all errors, but
> not mix the two.

On the contrary, this is exactly what the whole "imply" thing
demanded.

d1cbfd771ce82 (Nicolas Pitre       2016-11-11 172) #if IS_REACHABLE(CONFIG_PTP_1588_CLOCK)
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 173) 
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 174) /**
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 175)  * ptp_clock_register() - register a PTP hardware clock driver
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 176)  *
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 177)  * @info:   Structure describing the new clock.
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 178)  * @parent: Pointer to the parent device of the new clock.
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 179)  *
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 180)  * Returns a valid pointer on success or PTR_ERR on failure.  If PHC
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 181)  * support is missing at the configuration level, this function
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 182)  * returns NULL, and drivers are expected to gracefully handle that
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 183)  * case separately.
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 184)  */
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 185) 
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 186) extern struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
d1cbfd771ce82 (Nicolas Pitre       2016-11-11 187) 					    struct device *parent);

Thanks,
Richard