Received-SPF: pass (google.com: domain of linux-kernel+bounces-68641-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Date: Fri, 16 Feb 2024 15:28:40 +0200 (EET)
To: "Maciej W. Rozycki" <macro@orcam.me.uk>
cc: Bjorn Helgaas <bhelgaas@google.com>, linux-pci@vger.kernel.org, 
    LKML <linux-kernel@vger.kernel.org>, 
    Mika Westerberg <mika.westerberg@linux.intel.com>
Subject: Re: [PATCH 1/1] PCI: Cleanup link activation wait logic
In-Reply-To: <alpine.DEB.2.21.2402021359450.15781@angie.orcam.me.uk>
Message-ID: <ce73f41a-b529-726f-ee4e-9d0e0cee3320@linux.intel.com>
References: <20240202134108.4096-1-ilpo.jarvinen@linux.intel.com> <alpine.DEB.2.21.2402021359450.15781@angie.orcam.me.uk>
Precedence: bulk
MIME-Version: 1.0
Content-Type: multipart/mixed; BOUNDARY="8323328-1104822449-1708087900=:1097"
Content-ID: <8aebecf1-b380-ec81-f4e1-9ba90a0d18f8@linux.intel.com>

  This message is in MIME format.  The first part should be readable text,
  while the remaining parts are likely unreadable without MIME-aware tools.

--8323328-1104822449-1708087900=:1097
Content-Type: text/plain; CHARSET=ISO-8859-15
Content-Transfer-Encoding: QUOTED-PRINTABLE
Content-ID: <5bb50767-a43a-884b-8c39-8442de383a68@linux.intel.com>

On Fri, 2 Feb 2024, Maciej W. Rozycki wrote:

> On Fri, 2 Feb 2024, Ilpo J=E4rvinen wrote:
>=20
> > 1. Change pcie_failed_link_retrain() to return true only if link was
> >    retrained successfully due to the Target Speed quirk. If there is no
> >    LBMS set, return false instead of true because no retraining was
> >    even attempted. This seems correct considering expectations of both
> >    callers of pcie_failed_link_retrain().
>=20
>  You change the logic here in that the second conditional isn't run if th=
e=20
> first has not.  This is wrong, unclamping is not supposed to rely on LBMS=
=2E=20
> It is supposed to be always run and any failure has to be reported too, a=
s=20
> a retraining error.

Now that (I think) I fully understand the intent of the second=20
condition/block one additional question occurred to me.

How is the 2nd condition even supposed to work in the current place when=20
firmware has pre-arranged the 2.5GT/s resctriction? Wouldn't the link come=
=20
up fine in that case and the quirk code is not called at all since the=20
link came up successfully?


Yet another thing in this quirk code I don't like is how it can leaves the=
=20
target speed to 2.5GT/s when the quirk fails to get the link working=20
(which actually does happen in the disconnection cases because DLLLA won't=
=20
be set so the target speed will not be restored).


--=20
 i.
--8323328-1104822449-1708087900=:1097--