[PATCH] PCI: Add pcie_irq=other to enable non MSI/INTx interrupt for port service driver

[Liu Shengzhou-B36685]

> -----Original Message-----
> From: Kumar Gala [mailto:galak at kernel.crashing.org]
> Sent: Tuesday, July 10, 2012 11:50 PM
> To: Wood Scott-B07421
> Cc: Liu Shengzhou-B36685; bhelgaas at google.com; Wood Scott-B07421; linuxppc-
> dev at lists.ozlabs.org; linux-pci at vger.kernel.org
> Subject: Re: [PATCH] PCI: Add pcie_irq=other to enable non MSI/INTx interrupt
> for port service driver
> 
> 
> On Jul 10, 2012, at 10:31 AM, Scott Wood wrote:
> 
> > On 07/10/2012 01:13 AM, Liu Shengzhou-B36685 wrote:
> >>
> >>
> >>> -----Original Message-----
> >>> From: Wood Scott-B07421
> >>> Sent: Tuesday, July 10, 2012 12:39 AM
> >>> To: Liu Shengzhou-B36685
> >>> Cc: bhelgaas at google.com; linux-pci at vger.kernel.org; linuxppc-
> >>> dev at lists.ozlabs.org
> >>> Subject: Re: [PATCH] PCI: Add pcie_irq=other to enable non MSI/INTx
> >>> interrupt for port service driver
> >>>
> >>> On 07/09/2012 05:49 AM, Shengzhou Liu wrote:
> >>>> On some platforms, in RC mode, root port has neither MSI/MSI-X nor
> >>>> INTx interrupt generated, which are available only in EP mode on
> >>>> those
> >>> platform.
> >>>> In this case, we try to use other interrupt if supported (i.e.
> >>>> there is the shared error interrupt on platform P1010, P3041,
> >>>> P4080, etc) to have AER, Hot-plug, etc, services to work.
> >>>>
> >>>> Signed-off-by: Shengzhou Liu <Shengzhou.Liu at freescale.com>
> >>>> ---
> >>>> Documentation/kernel-parameters.txt |    4 ++++
> >>>> drivers/pci/pcie/portdrv_core.c     |   19 +++++++++++++++++++
> >>>> 2 files changed, 23 insertions(+), 0 deletions(-)
> >>>>
> >>>> diff --git a/Documentation/kernel-parameters.txt
> >>>> b/Documentation/kernel-parameters.txt
> >>>> index a92c5eb..af97c81 100644
> >>>> --- a/Documentation/kernel-parameters.txt
> >>>> +++ b/Documentation/kernel-parameters.txt
> >>>> @@ -2218,6 +2218,10 @@ bytes respectively. Such letter suffixes can
> >>>> also be
> >>> entirely omitted.
> >>>> 		nomsi	Do not use MSI for native PCIe PME signaling (this makes
> >>>> 			all PCIe root ports use INTx for all services).
> >>>>
> >>>> +	pcie_irq=	[PCIE] Native PCIe root port interrupt options:
> >>>> +		other	Try to use other interrupt when root port has
> >>>> +			neither MSI/MSI-X nor INTx support.
> >>>
> >>> Why does the user need to specify this?  Shouldn't this be a matter
> >>> of communication between kernel internals?
> >>>
> >>
> >> The "other interrupt" appears a non-standard interrupt way compared to
> MSI/MSI-X and INTx in point of PCIe spec.
> >
> > It still shouldn't be the user's responsibility to pass this in.
> 
> I agree with Scott, this should be done in board code or as a PCI fixup, not
> as a command line arg.
> 
> >> The intent of specifying this is to have an intervention and
> >> confirmation manually to avoid causing unexpected issue on some
> >> unknown platforms.
> >>
> >> I'm glad to remove the specified kernel parameter if it would be accepted
> upstream.
> >
> > Hopefully someone will comment if there is harm in doing this
> > unconditionally.  If there is, then we should handle this via a quirk
> > or similar mechanism.
> >
> > -Scott
> 
> If we need to do it via quirk, wondering if we can use the pci_dev_flags and
> set the flag in a quirk.
> 
> - k
 
Yes, it's better to do that with quirt way, I'm going to submit a new patch with that way.

Thanks,
Shengzhou