From: Lukas Wunner <lukas@wunner.de>
To: Alex_Gagniuc@Dellteam.com
Cc: mr.nuke.me@gmail.com, bhelgaas@google.com, Austin.Bolen@dell.com,
keith.busch@intel.com, Shyam.Iyer@dell.com,
gustavo@embeddedor.com, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] PCI: pciehp: Do not turn off slot if presence comes up after link
Date: Thu, 14 Feb 2019 08:01:00 +0100 [thread overview]
Message-ID: <20190214070100.kvikmkkcrp2d32sm@wunner.de> (raw)
In-Reply-To: <205e0fd9995a4f2b80ab370a974b6628@ausx13mps321.AMER.DELL.COM>
On Wed, Feb 13, 2019 at 06:55:46PM +0000, Alex_Gagniuc@Dellteam.com wrote:
> On 2/13/19 2:36 AM, Lukas Wunner wrote:
> > > (*) A bit hypothetical: There is no hardware yet implementing the ECN.
> >
> > Hm, this contradicts Austin Bolen's e-mail of Jan 25 that "Yes, this
> > platform disables in-band presence" (when asked whether your host
> > controller already adheres to the ECN).
>
> Both statements are true. The hardware does indeed disable in-band
> presence, in a rudimentary way that is not compliant with the ECN -- it
> doesn't implement the bits required by the ECN.
Ugh, can a BIOS update make those machines compliant to the ECN
or do we need a quirk specifically for them?
> > Polling PDS in
> > pcie_wait_for_link() or disabling either PDC or DLLSC if in-band presence
> > is disabled seems simpler to reason about.
>
> pcie_wait_for_link() is generic PCIe layer. I don't think mixing hotplug
> concepts is a good layering violation.
The function used to live in pciehp_hpc.c, but commits 9f5a70f18c58
and f0157160b359 moved it to generic code to allow code sharing with
the DPC driver. That's the only reason it's in generic code AFAICS.
> >> in-band PD disable (what's a good acronym for that, BTW?)
> >
> > I don't know, maybe inband_presence_disabled?
>
> PCI_EXP_SLTCAP2_IBPD ?
Yes, something like that. It should match the spec, which I have no
access to.
Thanks,
Lukas
next prev parent reply other threads:[~2019-02-14 7:01 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-05 21:06 [PATCH] PCI: pciehp: Do not turn off slot if presence comes up after link Alexandru Gagniuc
2019-02-08 19:56 ` Bjorn Helgaas
2019-02-09 11:58 ` Lukas Wunner
2019-02-11 23:48 ` Alex_Gagniuc
2019-02-12 8:30 ` Lukas Wunner
2019-02-12 10:37 ` Lukas Wunner
2019-02-12 23:57 ` Alex_Gagniuc
2019-02-13 8:36 ` Lukas Wunner
2019-02-13 18:55 ` Alex_Gagniuc
2019-02-14 7:01 ` Lukas Wunner [this message]
2019-02-14 19:26 ` Alex_Gagniuc
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