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

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Date: Thu, 11 Jan 2024 21:13:26 +0530
From: Ajay Agarwal <ajayagarwal@...gle.com>
To: Johan Hovold <johan@...nel.org>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc: Krzysztof Wilczyński <kw@...ux.com>,
	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 Fri, Jul 14, 2023 at 10:55:29AM +0200, Johan Hovold wrote:
> 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

Johan, Mani,
I submitted https://lore.kernel.org/all/20240111152517.1881382-1-ajayagarwal@google.com/
which does not return an error value if the dw_pcie_wait_for_link fails
in probe. Can you please check and provide your comments?

Thanks
Ajay