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Date:   Mon, 19 Jul 2021 17:06:06 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Pali =?iso-8859-1?Q?Roh=E1r?= <pali@kernel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        marek.vasut@gmail.com, linux-pci@vger.kernel.org,
        Marek Vasut <marek.vasut+renesas@gmail.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Wolfram Sang <wsa@the-dreams.de>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>,
        linux-renesas-soc@vger.kernel.org
Subject: Re: [PATCH V6] PCI: rcar: Add L1 link state fix into data abort hook
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On Mon, Jul 19, 2021 at 07:23:40PM +0200, Pali Rohár wrote:
> > On Sat, Jul 17, 2021 at 12:33:34PM -0500, Bjorn Helgaas wrote:

> > >   - "The R-Car PCIe controller is capable of handling L0s/L1 link
> > >     states."  AFAICT every PCIe device is required to handle L0 and L1
> > >     without software assistance.  So saying R-Car is "capable" puts a
> > >     better face on this than seems warranted.
> > > 
> > >     L0s doesn't seem relevant at all; at least it doesn't seem to play
> > >     a role in the patch.  There's no such thing as "returning to L0s"
> > >     as mentioned in the comment below; L0s is only reachable from L0.
> > >     Returns from L1 only go to L0 (PCIe r5.0, fig 5-1).
> 
> IIRC from L1 you can only go to Recovery. And from L0s you go to L0 or
> Recovery. But I do not know what is or was changed in PCIe r5.0.

Yes.  Per PCIe r5.0, fig 4-26, the LTSSM state diagram, that's still
the same.  The overview in Fig 5-1 doesn't include Recovery, Detect,
and othef LTSSM states.