Re: [PATCH v2] net: stmmac: correct MAC propagation delay

[Johannes Zink <j.zink@pengutronix.de>]

Hi Richard,

On 7/27/23 15:36, Richard Cochran wrote:
> On Thu, Jul 27, 2023 at 09:20:10AM +0200, Johannes Zink wrote:
>> Hi Richard,
>>
>> On 7/26/23 22:57, Richard Cochran wrote:
>>> On Mon, Jul 24, 2023 at 12:01:31PM +0200, Johannes Zink wrote:
>>>
>>> Earlier versions of the IP core return zero from these...
>>>
>>>> +#define	PTP_TS_INGR_LAT	0x68	/* MAC internal Ingress Latency */
>>>> +#define	PTP_TS_EGR_LAT	0x6c	/* MAC internal Egress Latency */
>>>
>>
>> good catch. Gonna send a v3 with a check to and set the values for dwmac v5 only.
> 
> AFAICT there is no feature bit that indicates the presence or absence
> of these two registers.
> 
> Are you sure that *all* v5 IP cores have these?
> 
> I am not sure.

I cannot tell for sure either, since I have datasheets for the i.MX8MP only. 
Maybe Kurt has some insights here, as he has additional hardware available for 
testing?

Nevertheless, I am going to add a guard to only use the correction codepath on 
i.MX8MP in v3 for the time being, we can add other hardware later trivially if 
they support doing this.

Best regards
Johannes

> 
> Thanks,
> Richard
> 
> 

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