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

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Message-ID: <ZLENgbMe4YVOINRQ@hovoldconsulting.com>
Date:   Fri, 14 Jul 2023 10:55:29 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Ajay Agarwal <ajayagarwal@...gle.com>
Cc:     Krzysztof Wilczyński <kw@...ux.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 Wed, Jul 12, 2023 at 11:15:54PM +0530, Ajay Agarwal wrote:
> On Tue, Jul 11, 2023 at 08:52:23AM +0200, Johan Hovold wrote:

> > 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.

> I am developing a PCIe driver which will not have the start_link
> callback defined. Instead, the link will be coming up much later based
> on some other trigger. So my driver will not attempt the LTSSM training
> on probe. So even if the probe is made asynchronous, it will still end
> up wasting 1 second of time.

Yeah, I had the suspicion that this was really motivated by some
out-of-tree driver, which as I'm sure you know, is not a concern for
mainline.

Vendor drivers do all sorts of crazy stuff and we don't carry code in
mainline for the sole benefit of such drivers that have not been
upstreamed (and likely never will be).

So again, I think this patch should just be reverted.

If you want to get something like this in, you can send a follow-on
patch describing your actual motivation and use case. But as it appears
to boil down to "I need this for my out-of-tree driver", I suspect such
a patch would still be rejected.

Johan