[PATCH v5 1/5] ARM/PCI: remove align_resource in pci_sys_data

[Gabriele Paoloni]

Hi Rob, Thanks for reviewing

> -----Original Message-----
> From: robherring2 at gmail.com [mailto:robherring2 at gmail.com] On Behalf Of Rob
> Herring
> Sent: 30 July 2015 23:48
> To: Lorenzo Pieralisi; Russell King - ARM Linux; Wangzhou (B)
> Cc: Bjorn Helgaas; Jingoo Han; Pratyush Anand; Arnd Bergmann; Gabriele Paoloni;
> James Morse; Liviu Dudau; thomas.petazzoni at free-electrons.com; Jason Cooper;
> linux-pci at vger.kernel.org; linux-arm-kernel at lists.infradead.org;
> devicetree at vger.kernel.org; Yuanzhichang; Zhudacai; zhangjukuo; qiuzhenfa;
> liudongdong (C); qiujiang; Kangfenglong; Liguozhu (Kenneth)
> Subject: Re: [PATCH v5 1/5] ARM/PCI: remove align_resource in pci_sys_data
> 
> On Tue, Jul 28, 2015 at 12:44 PM, Lorenzo Pieralisi
> <lorenzo.pieralisi at arm.com> wrote:
> > [CC'ing RMK]
> >
> > On Tue, Jul 28, 2015 at 08:17:18AM +0100, Zhou Wang wrote:
> >> On 2015/7/25 11:21, Zhou Wang wrote:
> >> > From: Gabriele Paoloni <gabriele.paoloni at huawei.com>
> >> >
> >> > This patch is needed in order to unify the PCIe designware framework for
> ARM and
> >> > ARM64 architectures. In the PCIe designware unification process we are
> calling
> >> > pci_create_root_bus() passing a "sysdata" parameter that is the same for
> both
> >> > ARM and ARM64 and is of type "struct pcie_port*". In the ARM case this
> will
> >> > cause a problem with the function pcibios_align_resource(); in fact this
> will
> >> > cast "dev->sysdata" to "struct pci_sys_data*", whereas designware had
> passed a
> >> > "struct pcie_port*" pointer.
> >> >
> >> > This patch solves the issue by removing "align_resource" from
> "pci_sys_data"
> >> > struct and defining a static global function pointer in "bios32.c"
> >> >
> >> > Signed-off-by: Gabriele Paoloni <gabriele.paoloni at huawei.com>
> >>
> >> Hi Arnd and Rob,
> >>
> >> What is your opinion about this patch? Gabriele adds a global pointer in
> bios32.c
> >> to store align_resource, so we could remove sys->align_resource in
> pcibios_align_resource.
> >>
> >> As Lorenzo mentioned in v4 series, this is a temporary solution before
> moving
> >> align_resource to host bridge structure.
> >>
> >> Any comments welcome.
> >
> > The align_resource() pointer is just used in drivers/pci/host/pci-mvebu.c,
> > I would like the pci-mvebu.c maintainers to comment on this and test it, I
> > do not expect it to create any issue and might be a temporary solution to
> > make progress on ARM/ARM64 consolidation, it is a blocking point.
> >
> > It would be good if Russell can have a look too, I do not see what
> > issue this can trigger given that is just used in:
> 
> It's Russell's call on this if you want to touch bios32.c...
> 
> >
> > drivers/pci/host/pci-mvebu.c
> >
> > and a global pointer (not saying it is elegant, but it should work)
> > might be ok.
> >
> > So yes, comments very welcome.
> 
> I may be wrong, but I don't think even mvebu needs this as part of
> pcibios_align_resource. pcibios_align_resource is called for every
> device, but all mvebu should care about is the alignment of the root
> bus BARs (and corresponding MBus windows) which can be handled in
> probe. I can't see how regions within there matter. But that is just
> my 10 minute look at it.

I think Thomas Petazzoni should answer this...right?  

> 
> If not, then I think align_resource should be a common per host
> function ptr. In other words, think about how to provide a default
> implementation of pcibios_align_resource. They almost all look the
> same to me with the same I/O 0x3xx address handling.

pcibios_align_resource already provides the default alignment job.
Are you suggesting to replace pcibios_align_resources implementation
with a stub and move the alignment job somewhere else...?

> 
> Rob