> -----Original Message----- > From: Benjamin Poirier [mailto:bpoir...@suse.com] > Sent: Thursday, May 10, 2018 12:29 AM > To: Kirsher, Jeffrey T <jeffrey.t.kirs...@intel.com> > Cc: Keller, Jacob E <jacob.e.kel...@intel.com>; Achim Mildenberger > <ad...@fph.physik.uni-karlsruhe.de>; olouvig...@gmail.com; > jaya...@goubiq.com; ehabk...@redhat.com; postmodern.m...@gmail.com; > bart.vanass...@wdc.com; intel-wired-...@lists.osuosl.org; > netdev@vger.kernel.org; linux-ker...@vger.kernel.org > Subject: [PATCH] e1000e: Ignore TSYNCRXCTL when getting I219 clock attributes > > There have been multiple reports of crashes that look like > kernel: RIP: 0010:[<ffffffff8110303f>] timecounter_read+0xf/0x50 > [...] > kernel: Call Trace: > kernel: [<ffffffffa0806b0f>] e1000e_phc_gettime+0x2f/0x60 [e1000e] > kernel: [<ffffffffa0806c5d>] e1000e_systim_overflow_work+0x1d/0x80 [e1000e] > kernel: [<ffffffff810992c5>] process_one_work+0x155/0x440 > kernel: [<ffffffff81099e16>] worker_thread+0x116/0x4b0 > kernel: [<ffffffff8109f422>] kthread+0xd2/0xf0 > kernel: [<ffffffff8163184f>] ret_from_fork+0x3f/0x70 > > These can be traced back to the fact that e1000e_systim_reset() skips the > timecounter_init() call if e1000e_get_base_timinca() returns -EINVAL, which > leads to a null deref in timecounter_read(). > > Commit 83129b37ef35 ("e1000e: fix systim issues", v4.2-rc1) reworked > e1000e_get_base_timinca() in such a way that it can return -EINVAL for > e1000_pch_spt if the SYSCFI bit is not set in TSYNCRXCTL. > > Some experimentation has shown that on I219 (e1000_pch_spt, "MAC: 12") > adapters, the E1000_TSYNCRXCTL_SYSCFI flag is unstable; TSYNCRXCTL reads > sometimes don't have the SYSCFI bit set. Retrying the read shortly after > finds the bit to be set. This was observed at boot (probe) but also link up > and link down. > > Moreover, the phc (PTP Hardware Clock) seems to operate normally even after > reads where SYSCFI=0. Therefore, remove this register read and > unconditionally set the clock parameters. > > Reported-by: Achim Mildenberger <ad...@fph.physik.uni-karlsruhe.de> > Message-Id: <20180425065243.g5mqewg5irkwgwgv@f2> > Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1075876 > Fixes: 83129b37ef35 ("e1000e: fix systim issues") > Signed-off-by: Benjamin Poirier <bpoir...@suse.com> > --- > drivers/net/ethernet/intel/e1000e/netdev.c | 15 ++++++--------- > 1 file changed, 6 insertions(+), 9 deletions(-) > > diff --git a/drivers/net/ethernet/intel/e1000e/netdev.c > b/drivers/net/ethernet/intel/e1000e/netdev.c > index ec4a9759a6f2..3afb1f3b6f91 100644 > --- a/drivers/net/ethernet/intel/e1000e/netdev.c > +++ b/drivers/net/ethernet/intel/e1000e/netdev.c > @@ -3546,15 +3546,12 @@ s32 e1000e_get_base_timinca(struct e1000_adapter > *adapter, u32 *timinca) > } > break; > case e1000_pch_spt: > - if (er32(TSYNCRXCTL) & E1000_TSYNCRXCTL_SYSCFI) { > - /* Stable 24MHz frequency */ > - incperiod = INCPERIOD_24MHZ; > - incvalue = INCVALUE_24MHZ; > - shift = INCVALUE_SHIFT_24MHZ; > - adapter->cc.shift = shift; > - break; > - } > - return -EINVAL; > + /* Stable 24MHz frequency */ > + incperiod = INCPERIOD_24MHZ; > + incvalue = INCVALUE_24MHZ; > + shift = INCVALUE_SHIFT_24MHZ; > + adapter->cc.shift = shift; > + break; > case e1000_pch_cnp: > if (er32(TSYNCRXCTL) & E1000_TSYNCRXCTL_SYSCFI) { > /* Stable 24MHz frequency */ > -- > 2.16.3
Given testing showing that the clock operates fine regardless of the register read, I think this is probably fine. Normally I believe the register was used to check which frequency was in use, but it doesn't seem to serve that purpose here. Thanks, Jake
