linux-kernel - Re: [PATCH v2 1/2] dp83640: Support a configurable number of periodic outputs

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Message-ID: <20140211200922.GA4254@netboy>
Date:	Tue, 11 Feb 2014 21:09:23 +0100
From:	Richard Cochran <richardcochran@...il.com>
To:	Stefan Sørensen 
	<stefan.sorensen@...ctralink.com>
Cc:	grant.likely@...aro.org, robh+dt@...nel.org, mark.rutland@....com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v2 1/2] dp83640: Support a configurable number of
 periodic outputs

On Tue, Feb 11, 2014 at 04:29:21PM +0100, Stefan Sørensen wrote:

> diff --git a/drivers/net/phy/dp83640.c b/drivers/net/phy/dp83640.c
> index 547725f..d4fe95d 100644
> --- a/drivers/net/phy/dp83640.c
> +++ b/drivers/net/phy/dp83640.c
> @@ -38,15 +38,11 @@
>  #define LAYER4		0x02
>  #define LAYER2		0x01
>  #define MAX_RXTS	64
> -#define N_EXT_TS	6
> +#define N_EXT		8
>  #define PSF_PTPVER	2
>  #define PSF_EVNT	0x4000
>  #define PSF_RX		0x2000
>  #define PSF_TX		0x1000
> -#define EXT_EVENT	1

Regarding this EXT_EVENT thing ...

> @@ -430,12 +419,12 @@ static int ptp_dp83640_enable(struct ptp_clock_info *ptp,
>  	switch (rq->type) {
>  	case PTP_CLK_REQ_EXTTS:
>  		index = rq->extts.index;
> -		if (index < 0 || index >= N_EXT_TS)
> +		if (index < 0 || index >= n_ext_ts)
>  			return -EINVAL;
> -		event_num = EXT_EVENT + index;
> +		event_num = index;

there was a mapping between the "event numbers" and the external time
stamp channels. I don't remember off the top of my head why this these
two differ by one, but there was a good reason.

Are you sure this is still working with this change?

I am especially wondering about the event decoding here:

> @@ -642,7 +631,7 @@ static void recalibrate(struct dp83640_clock *clock)
>  
>  static inline u16 exts_chan_to_edata(int ch)
>  {
> -	return 1 << ((ch + EXT_EVENT) * 2);
> +	return 1 << ((ch) * 2);
>  }

Maybe I am just paranoid, but can you remind me how these event
numbers are supposed to work, before and after the change?

Thanks,
Richard
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