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SubjectRE: [PATCH 6/6] ptp_ocelot: support 4 programmable pins
Date
Hi Richard,

> -----Original Message-----
> From: Richard Cochran <richardcochran@gmail.com>
> Sent: Wednesday, March 25, 2020 9:42 PM
> To: Y.b. Lu <yangbo.lu@nxp.com>
> Cc: linux-kernel@vger.kernel.org; netdev@vger.kernel.org; David S . Miller
> <davem@davemloft.net>; Vladimir Oltean <vladimir.oltean@nxp.com>;
> Claudiu Manoil <claudiu.manoil@nxp.com>; Andrew Lunn <andrew@lunn.ch>;
> Vivien Didelot <vivien.didelot@gmail.com>; Florian Fainelli
> <f.fainelli@gmail.com>; Alexandre Belloni <alexandre.belloni@bootlin.com>;
> Microchip Linux Driver Support <UNGLinuxDriver@microchip.com>
> Subject: Re: [PATCH 6/6] ptp_ocelot: support 4 programmable pins
>
> On Wed, Mar 25, 2020 at 03:08:46AM +0000, Y.b. Lu wrote:
>
> > The calling should be like this,
> > ptp_set_pinfunc (hold pincfg_mux)
> > ---> ptp_disable_pinfunc
> > ---> .enable
> > ---> ptp_find_pin (hold pincfg_mux)
>
> I see. The call
>
> ptp_disable_pinfunc() --> .enable()
>
> is really
>
> ptp_disable_pinfunc() --> .enable(on=0)
>
> or disable.
>
> All of the other drivers (except mv88e6xxx which has a bug) avoid the
> deadlock by only calling ptp_find_pin() when invoked by .enable(on=1);
>
> Of course, that is horrible, and I am going to find a way to fix it.

Thanks a lot.
Do you think it is ok to move protection into ptp_set_pinfunc() to protect just pin_config accessing?
ptp_disable_pinfunc() not touching pin_config could be out of protection.
But it seems indeed total ptp_set_pinfunc() should be under protection...

>
> For now, maybe you can drop the "programmable pins" feature for your
> driver? After all, the pins are not programmable.

I still want to confirm, did you mean the deadlock issue? Or you thought the pin supports only PTP_PF_PEROUT in hardware?
I could modify commit messages to indicate the pin supports both PTP_PF_PEROUT and PTP_PF_EXTTS, and PTP_PF_EXTTS support will be added in the future.
Thanks a lot.

>
> Thanks,
> Richard

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