Re: [PATCH v3 0/2] Tango PCIe controller support

From	Mason <slash.tmp@free.fr>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 0/2] Tango PCIe controller support
Date	2017-04-01 00:10 +0200
Message-ID	<trcU1-23j-5@gated-at.bofh.it> (permalink)
References	<tqk7f-6e9-3@gated-at.bofh.it> <tqPkK-3s9-19@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 30/03/2017 22:56, Mason wrote:

> I've run into an issue.
> 
> If I boot the system with earlyprintk enabled (as I've
> been doing throughout my dev), things work as expected.
> 
> But if I boot with earlyprintk disabled, then the system
> does not "see" the PCIe board, because reading the vendor
> ID returns 0xffffffff.
> 
> What we think is happening, is that when earlyprintk is
> disabled, the system proceeds much faster through the
> various inits, and the PCIe init happens when PCIe
> link training has not completed yet.
> 
> If that is the case, then it seems I would need to check
> the link state in my probe function.

I determined empirically that link training takes around
10-15 ms. Though I suppose this might depend on the
specific PCIe board? (I'm only considering x1 link.)

So I added an msleep(20); in the probe function, and in
the config_read callback, I check the link status on the
first read to the device.

Should I msleep(40) to be safe?

Regards.

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[PATCH v3 0/2] Tango PCIe controller support Marc Gonzalez <marc_gonzalez@sigmadesigns.com> - 2017-03-29 13:40 +0200
  [PATCH v3 1/2] PCI: Add tango MSI controller support Marc Gonzalez <marc_gonzalez@sigmadesigns.com> - 2017-03-29 13:40 +0200
    Re: [PATCH v3 1/2] PCI: Add tango MSI controller support Marc Zyngier <marc.zyngier@arm.com> - 2017-03-29 14:40 +0200
      Re: [PATCH v3 1/2] PCI: Add tango MSI controller support Mason <slash.tmp@free.fr> - 2017-03-29 15:20 +0200
        Re: [PATCH v3 1/2] PCI: Add tango MSI controller support Mason <slash.tmp@free.fr> - 2017-03-29 18:00 +0200
  [PATCH v3 2/2] PCI: Add tango PCIe host bridge support Marc Gonzalez <marc_gonzalez@sigmadesigns.com> - 2017-03-29 13:40 +0200
    Re: [PATCH v3 2/2] PCI: Add tango PCIe host bridge support Robin Murphy <robin.murphy@arm.com> - 2017-03-29 14:20 +0200
      Re: [PATCH v3 2/2] PCI: Add tango PCIe host bridge support Mason <slash.tmp@free.fr> - 2017-03-29 15:00 +0200
        Re: [PATCH v3 2/2] PCI: Add tango PCIe host bridge support Robin Murphy <robin.murphy@arm.com> - 2017-03-29 16:40 +0200
          RE: [PATCH v3 2/2] PCI: Add tango PCIe host bridge support David Laight <David.Laight@ACULAB.COM> - 2017-03-29 16:50 +0200
    Re: [PATCH v3 2/2] PCI: Add tango PCIe host bridge support Rob Herring <robh@kernel.org> - 2017-04-03 17:00 +0200
  Re: [PATCH v3 0/2] Tango PCIe controller support Mason <slash.tmp@free.fr> - 2017-03-30 23:00 +0200
    Re: [PATCH v3 0/2] Tango PCIe controller support Mason <slash.tmp@free.fr> - 2017-04-01 00:10 +0200

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