linux-kernel - Re: [PATCH] Revert "PCI: dwc: Wait for link up only if link is started"

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Message-ID: <ZKz8J1jM7zxt3wR7@hovoldconsulting.com>
Date:   Tue, 11 Jul 2023 08:52:23 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Krzysztof Wilczyński <kw@...ux.com>
Cc:     Ajay Agarwal <ajayagarwal@...gle.com>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Rob Herring <robh@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Bjorn Andersson <quic_bjorande@...cinc.com>,
        Sajid Dalvi <sdalvi@...gle.com>
Subject: Re: [PATCH] Revert "PCI: dwc: Wait for link up only if link is
 started"

On Tue, Jul 11, 2023 at 02:06:08AM +0900, Krzysztof Wilczyński wrote:

> > > > > > Finally, note that the intel-gw driver is the only driver currently not
> > > > > > providing a start_link callback and instead starts the link in its
> > > > > > host_init callback, and which may avoid an additional one-second timeout
> > > > > > during probe by making the link-up wait conditional. If anyone cares,
> > > > > > that can be done in a follow-up patch with a proper motivation.

> The whole conversation above about the intel-gw driver: would something
> need to be addressed here?  Or can I pick the suggested fix?

No, it's just another indication that the offending commit was confused.

All mainline drivers already start the link before that
wait-for-link-up, so the commit in question makes very little sense.
That's why I prefer reverting it, so as to not pollute the git logs
(e.g. for git blame) with misleading justifications.

> > > My apologies for adding this regression in some of the SOCs.
> > > May I suggest to keep my patch and make the following change instead?
> > > This shall keep the existing behavior as is, and save the boot time
> > > for drivers that do not define the start_link()?
> [...]
> 
> > I just realized that Fabio pushed exactly the same patch as I suggested
> > here:
> > https://lore.kernel.org/all/20230704122635.1362156-1-festevam@gmail.com/.
> > I think it is better we take it instead of reverting my commit.
> 
> Will do.  I will also make sure that we have correct attributions in place.

As I mentioned in the commit message, I think the commit should just be
reverted and if there's a valid argument to be made for a similar type
of change (without the breakage), that can be done as a follow-up with a
proper motivation.

Johan