[PATCH] ARM: Kirkwood: Support basic hotplug for PCI-E

[Andrew Lunn]

On Wed, Nov 21, 2012 at 01:35:27PM -0500, Jason Cooper wrote:
> On Wed, Nov 21, 2012 at 11:25:28AM -0700, Jason Gunthorpe wrote:
> > Unconditionally register the PCI-E bus, even if the link is currently
> > down. 
> 
> How does this affect clock gating on boards without PCI-E devices?  Will
> the SoC then power this unconditionally?

Hi Jason and Jason

I think it does.

The output from /debug/clk will tell.

I think it may also cause problems with udev persistent rules. The IDs
will change for devices which are on the second controller and the
first controller was previously not registered. I've not idea if this
is just a theoretical problem, or a real problem.

   Andrew

> 
> thx,
> 
> Jason.
> 
> > When the link is brought up the bus can be scanned through
> > /sys/bus/pci/rescan or otherwise. Since the HW has no interrupt for
> > link up, userspace will have to take care of the timing.
> > 
> > An earlier version of this was contingent on CONFIG_HOTPLUG, but
> > that is being removed from the kernel.
> > 
> > This also fixes printing the link up/down message to be displayed
> > on one line (structured logging broke this?)
> > 
> > Signed-off-by: Jason Gunthorpe <jgunthorpe at obsidianresearch.com>
> > ---
> >  arch/arm/mach-kirkwood/pcie.c |   10 +++-------
> >  1 files changed, 3 insertions(+), 7 deletions(-)
> > 
> > All PCI-E ports are required to support hot plug at the link training
> > level. Our systems support it electrically, and userspace sequences
> > everything to work properly. But the PCI-E root port needs to be
> > registered with the kernel to initiate a rescan via sysfs when things
> > are ready.
> > 
> > diff --git a/arch/arm/mach-kirkwood/pcie.c b/arch/arm/mach-kirkwood/pcie.c
> > index 59c97fe..80fd4f2 100644
> > --- a/arch/arm/mach-kirkwood/pcie.c
> > +++ b/arch/arm/mach-kirkwood/pcie.c
> > @@ -244,13 +244,9 @@ static struct hw_pci kirkwood_pci __initdata = {
> >  
> >  static void __init add_pcie_port(int index, void __iomem *base)
> >  {
> > -	printk(KERN_INFO "Kirkwood PCIe port %d: ", index);
> > -
> > -	if (orion_pcie_link_up(base)) {
> > -		printk(KERN_INFO "link up\n");
> > -		pcie_port_map[num_pcie_ports++] = index;
> > -	} else
> > -		printk(KERN_INFO "link down, ignoring\n");
> > +	pcie_port_map[num_pcie_ports++] = index;
> > +	pr_info("Kirkwood PCIe port %d: link %s\n", index,
> > +		orion_pcie_link_up(base) ? "up" : "down");
> >  }
> >  
> >  void __init kirkwood_pcie_init(unsigned int portmask)
> > -- 
> > 1.7.5.4
> >