Re: [RFC PATCH 0/2] arm: pcibios: remove pci_sys_data domain

[Liviu Dudau <Liviu.Dudau@arm.com>]

On Thu, Oct 30, 2014 at 05:03:05PM +0000, Jason Gunthorpe wrote:
> On Thu, Oct 30, 2014 at 04:52:46PM +0000, Lorenzo Pieralisi wrote:
> > On Thu, Oct 30, 2014 at 04:25:52PM +0000, Jason Gunthorpe wrote:
> > > On Thu, Oct 30, 2014 at 11:44:46AM +0000, Lorenzo Pieralisi wrote:
> > > 
> > > > Code in drivers/pci/pci-mvebu.c has been changed to add a domain
> > > > number to PCI resources by using the nr value coming from the setup
> > > > pcibios32 callback, which may not be correct and should be considered
> > > > a temporary solution waiting for review comments.
> > > 
> > > The intent of the string was to have the domain number so that
> > > resources in /proc/iomem can be correlated with lspci.
> > > 
> > > This would be a 'best practice' - all PCI drivers need to request
> > > resource, and the resource should be relatable back to the PCI
> > > domain... So it would be best if the domain number was available at
> > > this point in a driver's flow.
> > 
> > It is not available with the new approach and the generic PCI domains since
> > the set-up hook is called before creating the pci_bus. That's why
> > I mentioned that in the cover letter, and that's good it caught your
> > attention.
> > 
> > On a side note, when the resources are parsed from DT ranges, ie in:
> > 
> > of_pci_get_host_bridge_resources()
> > 
> > the resources won't contain the domain number you are looking for here, for
> > the records, so we'd better find an agreement sooner rather than later.
> 
> Well, it is very unfortunate that things are globally not sequenced to
> allow proper resource names :(

But of_pci_get_host_bridge_resources() does not request the resources, it only
creates them out of the DT ranges. If/when the driver decides the list of
resources is correct and it can work with it can also request them and use
whatever domain number allocation strategy it wants (auto-incrementing or DT
based). So I don't think the global sequencing is broken here.

Best regards,
Liviu

> 
> But it also isn't really a big deal in the grand scheme of
> things. Maybe it can be fixed later :|
> 
> > So basically I could go as far as sticking 0000 to the string given the
> > current code. I did not drop the 0x04x entirely since I do not want to break
> > userspace, I was tempted though, let me know if I am allowed to do that.
> 
> I'd just drop it entirely then, nobody is going to parse /proc/iomem
> 
> Jason
> 

-- 
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