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Message-ID: <20150810084949.GA18566@localhost.localdomain>
Date: Mon, 10 Aug 2015 10:49:49 +0200
From: Richard Cochran <richardcochran@...il.com>
To: Christopher Hall <christopher.s.hall@...el.com>
Cc: john.stultz@...aro.org, tglx@...utronix.de, mingo@...hat.com,
jeffrey.t.kirsher@...el.com, john.ronciak@...el.com, hpa@...or.com,
x86@...nel.org, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org
Subject: Re: [PATCH v2 4/4] Added getsynctime64() callback
On Fri, Aug 07, 2015 at 04:01:35PM -0700, Christopher Hall wrote:
> --- a/drivers/net/ethernet/intel/e1000e/defines.h
> +++ b/drivers/net/ethernet/intel/e1000e/defines.h
> @@ -527,6 +527,13 @@
> #define E1000_RXCW_C 0x20000000 /* Receive config */
> #define E1000_RXCW_SYNCH 0x40000000 /* Receive config synch */
>
> +/* HH Time Sync */
> +#define E1000_TSYNCTXCTL_MAX_ALLOWED_DLY_MASK 0x0000F000 /* max delay */
> +#define E1000_TSYNCTXCTL_SYNC_COMP 0x40000000 /* sync complete
> + */
> +#define E1000_TSYNCTXCTL_START_SYNC 0x80000000 /* initiate sync
> + */
Split comment looks bad. Trim this leading space instead. ^^^^^^
> @@ -98,6 +100,91 @@ static int e1000e_phc_adjtime(struct ptp_clock_info *ptp, s64 delta)
> return 0;
> }
>
> +#define HW_WAIT_COUNT (2)
> +#define HW_RETRY_COUNT (2)
A busy wait, plus a retry, ...
> +#define SYNCTIME_RETRY_COUNT (2)
plus another retry!
Seems a bit heavy handed to me. Is the HW really that flakey?
I would expect that a reasonably long polling loop should be
sufficient. If not, then the HW ignores certain requests, and that is
worth a comment.
In any case, I don't understand why you have two nested retry loops.
> +static int e1000e_phc_getsynctime(struct ptp_clock_info *ptp,
> + struct timespec64 *devts,
> + struct timespec64 *systs)
> +{
> + struct e1000_adapter *adapter = container_of(ptp, struct e1000_adapter,
> + ptp_clock_info);
> + unsigned long flags;
> + u32 remainder;
> + struct correlated_ts art_correlated_ts;
> + u64 device_time;
> + int i, ret;
> +
> + if (!cpu_has_art)
> + return -EOPNOTSUPP;
Perform this check before registration, setting .getsynctime64
accordingly.
Thanks,
Richard
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