Re: radeon: RFC speed cap detection on ppc64

2012-10-23 Thread Bjorn Helgaas
On Mon, Oct 22, 2012 at 9:44 AM, Alan Cox wrote: >> That (walking all parent nodes) is probably the safest thing to do. I'm >> not sure whether it's optimal. It would likely depend on whether you >> can meaningfully have a bridge that's faster on the downstream side than >> on the upstream. > >

radeon: RFC speed cap detection on ppc64

2012-10-22 Thread Alan Cox
> That (walking all parent nodes) is probably the safest thing to do. I'm > not sure whether it's optimal. It would likely depend on whether you > can meaningfully have a bridge that's faster on the downstream side than > on the upstream. This is architecture goo at heart - would this be bett

radeon: RFC speed cap detection on ppc64

2012-10-22 Thread Adam Jackson
On 10/19/12 1:43 PM, Lucas Kannebley Tavares wrote: > The radeon driver does speed cap detection on the root PCI device for > the maximum speed with which the adapter can communicate. On ppc64 > systems, however, the root device belongs to the Hypervisor, so the > current code would case a null poi

radeon: RFC speed cap detection on ppc64

2012-10-22 Thread Bjorn Helgaas
On Mon, Oct 22, 2012 at 9:44 AM, Alan Cox wrote: >> That (walking all parent nodes) is probably the safest thing to do. I'm >> not sure whether it's optimal. It would likely depend on whether you >> can meaningfully have a bridge that's faster on the downstream side than >> on the upstream. > >

Re: radeon: RFC speed cap detection on ppc64

2012-10-22 Thread Alan Cox
> That (walking all parent nodes) is probably the safest thing to do. I'm > not sure whether it's optimal. It would likely depend on whether you > can meaningfully have a bridge that's faster on the downstream side than > on the upstream. This is architecture goo at heart - would this be bett

Re: radeon: RFC speed cap detection on ppc64

2012-10-22 Thread Adam Jackson
On 10/19/12 1:43 PM, Lucas Kannebley Tavares wrote: The radeon driver does speed cap detection on the root PCI device for the maximum speed with which the adapter can communicate. On ppc64 systems, however, the root device belongs to the Hypervisor, so the current code would case a null pointer d

radeon: RFC speed cap detection on ppc64

2012-10-21 Thread Lucas Kannebley Tavares
The radeon driver does speed cap detection on the root PCI device for the maximum speed with which the adapter can communicate. On ppc64 systems, however, the root device belongs to the Hypervisor, so the current code would case a null pointer dereference. I propose to look for the outmost bus

radeon: RFC speed cap detection on ppc64

2012-10-19 Thread Lucas Kannebley Tavares
The radeon driver does speed cap detection on the root PCI device for the maximum speed with which the adapter can communicate. On ppc64 systems, however, the root device belongs to the Hypervisor, so the current code would case a null pointer dereference. I propose to look for the outmost bus