Re: [RESEND: RFC PATCH 3/3] pcie: keystone: add pcie driver based on designware core driver

[Murali Karicheri]

On 4/2/2014 12:47 PM, Andrew Murray wrote:
> On 2 April 2014 16:43, Murali Karicheri <m-karicheri2@xxxxxx> wrote:
>
> > Keystone pcie driver is developed based on other dw based pcie drivers
> >
> > such as pci-exynos that uses subsys_initcall(). I am new to this list,
> >
> > probably Jingoo (copied) has some history on why we can't use module.
> > For now I will keep it as is and can be re-visited in the next revisions.
> > Also I will experiment with PCIE port driver as well.
> >
> >
> > BTW, PCIE driver currently uses Legacy or MSI IRQ. Keystone PCI has
> > a platform IRQ. Is DT based irq configuration is the appropriate way
> > to add this capability?
> As far as I am aware - the PCI standards define a particular way for
> devices to describe which interrupt will be used for things like
> hotplug, AER and PME. These interrupts are always PCI interrupts (i.e.
> MSI/MSI-X/legacy). Thus the port services code in the kernel uses
> standard configuration space accesses to determine the interrupt to
> use. Also note that it's not just the host bridge that can provide
> these services but any PCIE device, I guess in this sense a host
> bridge is treated like any other device.
>
> If my understanding is correct I don't believe the current port
> services code allows exceptions to this, i.e. to say this host bridge
> actually uses a platform IRQ for AER rather than an MSI. Though this
> may be quite useful as I suspect many host bridges provide interrupts
> for things like PME through platform IRQs rather that PCI interrupts.
>
> Does the Keystone have platform IRQs for things like AER? Is that
> because the IP makes these events available through platform IRQs in
> addition to the standard PCI means?
>
> Andrew Murray
Andrew,

Yes. Keystone PCIe hw is based on designware hw version v3.65 that 
implements
Error interrupt as a platform IRQ only (not in addition) and 
unfortunately standard
PCI means are not supported. The latter versions do support standard PCI 
means.

Murali

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