linux-kernel - Re: [PATCH v2 2/2] PCI: Add missing link delays required by the PCIe spec

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Message-ID: <20191106133137.GN2552@lahna.fi.intel.com>
Date:   Wed, 6 Nov 2019 15:31:37 +0200
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, Lukas Wunner <lukas@...ner.de>,
        Keith Busch <keith.busch@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Alexandru Gagniuc <mr.nuke.me@...il.com>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Paul Menzel <pmenzel@...gen.mpg.de>,
        Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] PCI: Add missing link delays required by the PCIe
 spec

On Tue, Nov 05, 2019 at 02:01:05PM -0600, Bjorn Helgaas wrote:
> > I feel that the following is the right place to perform the delay but if
> > you think we can ignore the above, I will just do what you say and do it
> > in pci_pm_default_resume_early() (and pci_restore_standard_config() for
> > runtime path).
> > 
> > [The below diff does not have check for pci_dev->skip_bus_pm because I
> >  was planning to move it inside pci_bridge_wait_for_secondary_bus() itself.]
> 
> What do you gain by moving it?  IIUC we want them to be the same
> condition, and if one is in pci_pm_resume_noirq() and another is
> inside pci_bridge_wait_for_secondary_bus(), it's hard to see that
> they're connected.  I'd rather have pci_pm_resume_noirq() check it
> once, save the result, and test that result before calling
> pci_pm_default_resume_early() and pci_bridge_wait_for_secondary_bus().

Fair enough :)