linux-kernel - RE: [Intel-wired-lan] [PATCH] e1000e: fix timing for 82579 Gigabit Ethernet controller

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Message-ID: <02874ECE860811409154E81DA85FBB5857D7F361@ORSMSX115.amr.corp.intel.com>
Date:   Tue, 28 Feb 2017 21:09:35 +0000
From:   "Keller, Jacob E" <jacob.e.keller@...el.com>
To:     "Neftin, Sasha" <sasha.neftin@...el.com>,
        Bernd Faust <berndfaust@...il.com>,
        "Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
        "intel-wired-lan@...ts.osuosl.org" <intel-wired-lan@...ts.osuosl.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [Intel-wired-lan] [PATCH] e1000e: fix timing for 82579 Gigabit
 Ethernet controller

> -----Original Message-----
> From: Intel-wired-lan [mailto:intel-wired-lan-bounces@...ts.osuosl.org] On
> Behalf Of Neftin, Sasha
> Sent: Monday, February 27, 2017 12:40 AM
> To: Bernd Faust <berndfaust@...il.com>; Kirsher, Jeffrey T
> <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 2/26/2017 11:08, Neftin, Sasha wrote:
> > 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
> >
> I've double checked - 82579 support 96MHz frequency only. So, let's
> accept this suggestion to upstream.
> 
> Ack.
> 

This resolves also a complaint from someone on the LinuxPTP development mailing list.

ACK.

Thanks,
Jake

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