Re: [PATCH v2 2/2] PTP: add support for one-shot output

[Felipe Balbi]

Hi,

Richard Cochran <richardcoch...@gmail.com> writes:
> On Fri, Aug 30, 2019 at 11:00:20AM +0300, Felipe Balbi wrote:
>> >> @@ -177,9 +177,8 @@ long ptp_ioctl(struct posix_clock *pc, unsigned int 
>> >> cmd, unsigned long arg)
>> >>                   err = -EFAULT;
>> >>                   break;
>> >>           }
>> >> -         if ((req.perout.flags || req.perout.rsv[0] || req.perout.rsv[1]
>> >> -                         || req.perout.rsv[2] || req.perout.rsv[3])
>> >> -                 && cmd == PTP_PEROUT_REQUEST2) {
>> >> +         if ((req.perout.rsv[0] || req.perout.rsv[1] || req.perout.rsv[2]
>> >> +                 || req.perout.rsv[3]) && cmd == PTP_PEROUT_REQUEST2) {
>> >
>> > Please check that the reserved bits of req.perout.flags, namely
>> > ~PTP_PEROUT_ONE_SHOT, are clear.
>> 
>> Actually, we should check more. PEROUT_FEATURE_ENABLE is still valid
>> here, right? So are RISING and FALLING edges, no?
>
> No.  The ptp_extts_request.flags are indeed defined:
>
> struct ptp_extts_request {
>       ...
>       unsigned int flags;  /* Bit field for PTP_xxx flags. */
>       ...
> };
>
> But the ptp_perout_request.flags are reserved:
>
> struct ptp_perout_request {
>       ...
>       unsigned int flags;           /* Reserved for future use. */
>       ...
> };

This a bit confusing, really. Specially when the comment right above
those flags states:

/* PTP_xxx bits, for the flags field within the request structures. */

The request "structures" include EXTTS and PEROUT:

struct ptp_clock_request {
        enum {
                PTP_CLK_REQ_EXTTS,
                PTP_CLK_REQ_PEROUT,
                PTP_CLK_REQ_PPS,
        } type;
        union {
                struct ptp_extts_request extts;
                struct ptp_perout_request perout;
        };
};

Seems like we will, at least, make it clear which flags are valid for
which request structures.

> For this ioctl, the test for enable/disable is
> ptp_perout_request.period is zero:
>
>               enable = req.perout.period.sec || req.perout.period.nsec;
>               err = ops->enable(ops, &req, enable);
>
> The usage pattern here is taken from timer_settime(2).

got it

-- 
balbi

signature.asc
Description: PGP signature