netdev - Re: [Intel-wired-lan] [PATCH] e1000e: fix timing for 82579 Gigabit Ethernet controller

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Message-ID: <0a95307e-6683-b9fe-1957-be2b0a3c441e@intel.com>
Date:   Sun, 26 Feb 2017 11:08:08 +0200
From:   "Neftin, Sasha" <sasha.neftin@...el.com>
To:     Bernd Faust <berndfaust@...il.com>,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [Intel-wired-lan] [PATCH] e1000e: fix timing for 82579 Gigabit
 Ethernet controller

On 2/19/2017 14:55, Neftin, Sasha wrote:
> On 2/16/2017 20:42, Bernd Faust wrote:
>> After an upgrade to Linux kernel v4.x the hardware timestamps of the
>> 82579 Gigabit Ethernet Controller are different than expected.
>> The values that are being read are almost four times as big as before
>> the kernel upgrade.
>>
>> The difference is that after the upgrade the driver sets the clock
>> frequency to 25MHz, where before the upgrade it was set to 96MHz. Intel
>> confirmed that the correct frequency for this network adapter is 96MHz.
>>
>> Signed-off-by: Bernd Faust <berndfaust@...il.com>
>> ---
>>   drivers/net/ethernet/intel/e1000e/netdev.c | 6 ++++++
>>   1 file changed, 6 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c 
>> b/drivers/net/ethernet/intel/e1000e/netdev.c
>> index 7017281..8b7113d 100644
>> --- a/drivers/net/ethernet/intel/e1000e/netdev.c
>> +++ b/drivers/net/ethernet/intel/e1000e/netdev.c
>> @@ -3511,6 +3511,12 @@ s32 e1000e_get_base_timinca(struct 
>> e1000_adapter *adapter, u32 *timinca)
>>
>>       switch (hw->mac.type) {
>>       case e1000_pch2lan:
>> +        /* Stable 96MHz frequency */
>> +        incperiod = INCPERIOD_96MHz;
>> +        incvalue = INCVALUE_96MHz;
>> +        shift = INCVALUE_SHIFT_96MHz;
>> +        adapter->cc.shift = shift + INCPERIOD_SHIFT_96MHz;
>> +        break;
>>       case e1000_pch_lpt:
>>           if (er32(TSYNCRXCTL) & E1000_TSYNCRXCTL_SYSCFI) {
>>               /* Stable 96MHz frequency */
>> -- 
>> 2.7.4
>> _______________________________________________
>> Intel-wired-lan mailing list
>> Intel-wired-lan@...ts.osuosl.org
>> http://lists.osuosl.org/mailman/listinfo/intel-wired-lan
>
> Hello,
>
> e1000_pch2lan mac type corresponds to 82579LM and 82579V network 
> adapters. System clock frequency indication (SYSCFI) for these devices 
> supports both 25MHz and 96MHz frequency. By default TSYNCRXCTL.SYSCFI 
> is set to 1 and that means 96MHz frequency is picked.
>
> It is better to keep the current implementation as it covers all options.
>
> Thanks,
>
> Sasha
>
Hello,

During last couple of weeks I saw few  complaints from community on same 
timing problem with 82579. I will double check clock definition with HW 
architecture.

Sasha

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