Resetting PCI-E devices after linux boot

Resetting PCI-E devices after linux boot

[Dan Wilson]

We are building a PCI-E device for use in an embedded system with an 
85xx processor.  One of our customers is adamant that linux PCI-E 
hot-swap support will not allow us to either bring the device up after 
linux boot (i.e., the PCI-E device must be present when linux scans for 
PCI-E devices at startup) or to reset the device once linux is up.  It 
was our impression that the PCI-E hot-swap support should allow for 
devices to appear after linux boot, be properly initialized, and then 
later be able to shut them down and bring them back up again.

Has anyone successfully used the PCI-E hot-swap capabilities in the 
linux kernel in a PPC 85xx environment?  Any known gotchas we need to be 
aware of?

Thanks in advance for your responses,

Dan.

Re: Resetting PCI-E devices after linux boot

[Jake Magee]

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Dan,

Were you able to get PCI-E hotplug working?  I could not get this working
myself and assumed that driver support was lacking.  I'm actually using a
PPC405.

Thanks,
Jake


On Thu, Mar 25, 2010 at 8:26 PM, Dan Wilson <dwilson@fulcrummicro.com>wrote:

> We are building a PCI-E device for use in an embedded system with an 85xx
> processor.  One of our customers is adamant that linux PCI-E hot-swap
> support will not allow us to either bring the device up after linux boot
> (i.e., the PCI-E device must be present when linux scans for PCI-E devices
> at startup) or to reset the device once linux is up.  It was our impression
> that the PCI-E hot-swap support should allow for devices to appear after
> linux boot, be properly initialized, and then later be able to shut them
> down and bring them back up again.
>
> Has anyone successfully used the PCI-E hot-swap capabilities in the linux
> kernel in a PPC 85xx environment?  Any known gotchas we need to be aware of?
>
> Thanks in advance for your responses,
>
> Dan.
>
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
>

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Re: Resetting PCI-E devices after linux boot

[Benjamin Herrenschmidt]

On Wed, 2010-04-14 at 08:55 -0500, Jake Magee wrote:
> On Thu, Mar 25, 2010 at 8:26 PM, Dan Wilson <dwilson@fulcrummicro.com>
> wrote:
>         We are building a PCI-E device for use in an embedded system
>         with an 85xx processor.  One of our customers is adamant that
>         linux PCI-E hot-swap support will not allow us to either bring
>         the device up after linux boot (i.e., the PCI-E device must be
>         present when linux scans for PCI-E devices at startup) or to
>         reset the device once linux is up.  It was our impression that
>         the PCI-E hot-swap support should allow for devices to appear
>         after linux boot, be properly initialized, and then later be
>         able to shut them down and bring them back up again.
>         
>         Has anyone successfully used the PCI-E hot-swap capabilities
>         in the linux kernel in a PPC 85xx environment?  Any known
>         gotchas we need to be aware of?
>         
>         Thanks in advance for your responses,

It should be possible to get that working, but I suspect not without
some code changes. I know the current PCIe hotswap driver has ACPI hooks
that would need to be replaced by appropriate hooks into the powerpc
code to perform the right resource manipulation etc...

We do PCIe hotswap on IBM pSeries, but this is using specific FW
interfaces for which we have a dedicated PCI hotplug driver.

Can the slot power be SW controlled on the Canyonlands PCIe slot ? In
that case I should be able to toy with that myself at some stage (but
not for a couple of weeks).

Cheers,
Ben.

Re: Resetting PCI-E devices after linux boot

[Stefan Roese]

Hi Ben,

On Thursday 15 April 2010 00:25:23 Benjamin Herrenschmidt wrote:
> It should be possible to get that working, but I suspect not without
> some code changes. I know the current PCIe hotswap driver has ACPI hooks
> that would need to be replaced by appropriate hooks into the powerpc
> code to perform the right resource manipulation etc...
> 
> We do PCIe hotswap on IBM pSeries, but this is using specific FW
> interfaces for which we have a dedicated PCI hotplug driver.
> 
> Can the slot power be SW controlled on the Canyonlands PCIe slot ?

No. I just checked the schematics. PCIe power supply is directly connected to 
the board power supplies.

Cheers,
Stefan