From: "Pali Rohár" <pali@kernel.org>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: "Bjorn Helgaas" <helgaas@kernel.org>,
vtolkm@gmail.com, linux-pci@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
"Rob Herring" <robh@kernel.org>,
"Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
"Marek Behún" <marek.behun@nic.cz>,
"Thomas Petazzoni" <thomas.petazzoni@bootlin.com>,
"Jason Cooper" <jason@lakedaemon.net>
Subject: Re: PCI trouble on mvebu (Turris Omnia)
Date: Fri, 30 Oct 2020 15:23:37 +0100 [thread overview]
Message-ID: <20201030142337.yushrdcuecycfhcu@pali> (raw)
In-Reply-To: <87k0v7n9y9.fsf@toke.dk>
On Friday 30 October 2020 14:02:22 Toke Høiland-Jørgensen wrote:
> Pali Rohár <pali@kernel.org> writes:
> > My experience with that WLE900VX card, aardvark driver and aspm code:
> >
> > Link training in GEN2 mode for this card succeed only once after reset.
> > Repeated link retraining fails and it fails even when aardvark is
> > reconfigured to GEN1 mode. Reset via PERST# signal is required to have
> > working link training.
> >
> > What I did in aardvark driver: Set mode to GEN2, do link training. If
> > success read "negotiated link speed" from "Link Control Status Register"
> > (for WLE900VX it is 0x1 - GEN1) and set it into aardvark. And then
> > retrain link again (for WLE900VX now it would be at GEN1). After that
> > card is stable and all future retraining (e.g. from aspm.c) also passes.
> >
> > If I do not change aardvark mode from GEN2 to GEN1 the second link
> > training fails. And if I change mode to GEN1 after this failed link
> > training then nothing happen, link training do not success.
> >
> > So just speculation now... In current setup initialization of card does
> > one link training at GEN2. Then aspm.c is called which is doing second
> > link retraining at GEN2. And if it fails then below patch issue third
> > link retraining at GEN1. If A38x/pci-mvebu has same problem as aardvark
> > then second link retraining must be at GEN1 (not GEN2) to workaround
> > this issue.
> >
> > Bjorn, Toke: what about trying to hack aspm.c code to never do link
> > retraining at GEN2 speed? And always force GEN1 speed prior link
> > training?
>
> Sounds like a plan. I poked around in aspm.c and must confess to being a
> bit lost in the soup of registers ;)
>
> So if one of you can cook up a patch, that would be most helpful!
I modified Bjorn's patch, explicitly set tls to 1 and added debug info
about cls (current link speed, that what is used by aardvark). It is
untested, I just tried to compile it.
Can try it?
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 253c30cc1967..f934c0b52f41 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -206,6 +206,27 @@ static bool pcie_retrain_link(struct pcie_link_state *link)
unsigned long end_jiffies;
u16 reg16;
+ u32 lnkcap2;
+ u16 lnksta, lnkctl2, cls, tls;
+
+ pcie_capability_read_dword(parent, PCI_EXP_LNKCAP2, &lnkcap2);
+ pcie_capability_read_word(parent, PCI_EXP_LNKSTA, &lnksta);
+ pcie_capability_read_word(parent, PCI_EXP_LNKCTL2, &lnkctl2);
+ cls = lnksta & PCI_EXP_LNKSTA_CLS;
+ tls = lnkctl2 & PCI_EXP_LNKCTL2_TLS;
+
+ pci_info(parent, "lnkcap2 %#010x sls %#04x lnksta %#06x cls %#03x lnkctl2 %#06x tls %#03x\n",
+ lnkcap2, (lnkcap2 & 0x3F) >> 1,
+ lnksta, cls,
+ lnkctl2, tls);
+
+ tls = 1;
+ pcie_capability_clear_and_set_word(parent, PCI_EXP_LNKCTL2,
+ PCI_EXP_LNKCTL2_TLS, tls);
+ pcie_capability_read_word(parent, PCI_EXP_LNKCTL2, &lnkctl2);
+ pci_info(parent, "lnkctl2 %#010x new tls %#03x\n",
+ lnkctl2, tls);
+
pcie_capability_read_word(parent, PCI_EXP_LNKCTL, ®16);
reg16 |= PCI_EXP_LNKCTL_RL;
pcie_capability_write_word(parent, PCI_EXP_LNKCTL, reg16);
@@ -227,6 +248,8 @@ static bool pcie_retrain_link(struct pcie_link_state *link)
break;
msleep(1);
} while (time_before(jiffies, end_jiffies));
+ pci_info(parent, "lnksta %#06x new cls %#03x\n",
+ lnksta, (cls & PCI_EXP_LNKSTA_CLS));
return !(reg16 & PCI_EXP_LNKSTA_LT);
}
next prev parent reply other threads:[~2020-10-30 14:23 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-27 15:43 PCI trouble on mvebu (Turris Omnia) Toke Høiland-Jørgensen
2020-10-27 17:20 ` Bjorn Helgaas
2020-10-27 17:44 ` ™֟☻̭҇ Ѽ ҉ ®
2020-10-27 18:59 ` Toke Høiland-Jørgensen
2020-10-27 20:20 ` Toke Høiland-Jørgensen
2020-10-27 21:22 ` ™֟☻̭҇ Ѽ ҉ ®
2020-10-27 21:31 ` Toke Høiland-Jørgensen
2020-10-27 22:01 ` ™֟☻̭҇ Ѽ ҉ ®
2020-10-27 22:12 ` Toke Høiland-Jørgensen
2020-10-27 18:56 ` Toke Høiland-Jørgensen
2020-10-28 13:36 ` Toke Høiland-Jørgensen
2020-10-28 14:42 ` Bjorn Helgaas
2020-10-28 15:08 ` Toke Høiland-Jørgensen
2020-10-28 16:40 ` ™֟☻̭҇ Ѽ ҉ ®
2020-10-28 23:16 ` Bjorn Helgaas
2020-10-29 10:09 ` Pali Rohár
2020-10-29 10:56 ` ™֟☻̭҇ Ѽ ҉ ®
2020-10-29 11:12 ` Toke Høiland-Jørgensen
2020-10-29 19:30 ` Bjorn Helgaas
2020-10-29 19:56 ` ™֟☻̭҇ Ѽ ҉ ®
2020-10-29 19:57 ` Andrew Lunn
2020-10-29 21:55 ` Thomas Petazzoni
2020-10-29 20:18 ` Toke Høiland-Jørgensen
2020-10-29 22:09 ` Toke Høiland-Jørgensen
2020-10-29 20:58 ` Marek Behun
2020-10-30 10:08 ` Pali Rohár
2020-10-30 10:45 ` Marek Behun
2020-10-29 21:54 ` Thomas Petazzoni
2020-10-29 23:15 ` Toke Høiland-Jørgensen
2020-10-30 8:23 ` Thomas Petazzoni
2020-10-30 10:15 ` Pali Rohár
2020-10-29 10:41 ` Toke Høiland-Jørgensen
2020-10-29 11:18 ` ™֟☻̭҇ Ѽ ҉ ®
2020-10-30 11:23 ` Pali Rohár
2020-10-30 13:02 ` Toke Høiland-Jørgensen
2020-10-30 14:23 ` Pali Rohár [this message]
2020-10-30 14:54 ` ™֟☻̭҇ Ѽ ҉ ®
2020-10-31 12:49 ` Toke Høiland-Jørgensen
2020-11-02 15:24 ` Pali Rohár
2020-11-02 15:54 ` Toke Høiland-Jørgensen
2020-11-02 16:18 ` ™֟☻̭҇ Ѽ ҉ ®
2020-11-02 16:33 ` Toke Høiland-Jørgensen
2021-03-15 19:58 ` Pali Rohár
2021-03-16 9:25 ` Pali Rohár
2021-03-18 22:43 ` Toke Høiland-Jørgensen
2021-03-18 23:16 ` Pali Rohár
2021-03-26 12:50 ` Pali Rohár
2021-03-26 15:25 ` Toke Høiland-Jørgensen
2021-03-26 15:34 ` Pali Rohár
2021-03-26 16:54 ` Toke Høiland-Jørgensen
2021-03-26 17:11 ` Pali Rohár
2021-03-26 17:51 ` Toke Høiland-Jørgensen
2021-03-29 17:09 ` Pali Rohár
2021-03-31 14:02 ` Toke Høiland-Jørgensen
2021-03-31 16:15 ` Pali Rohár
2021-03-31 16:53 ` Toke Høiland-Jørgensen
2020-10-29 1:21 ` Marek Behun
2020-10-29 15:12 ` Rob Herring
2020-10-27 18:03 ` Marek Behun
2020-10-27 19:00 ` Toke Høiland-Jørgensen
2020-10-27 20:19 ` Marek Behun
2020-10-27 20:49 ` Toke Høiland-Jørgensen
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