Re: [PATCH 4/5] PCI: designware: Add setup bus-related to pcie_host_ops

[Arnd Bergmann]

On Monday 19 January 2015 13:38:53 Gabriel Fernandez wrote:
> 
> On 18 December 2014 at 05:58, Jingoo Han <jg1.han@xxxxxxxxxxx> wrote:
> 
> > On Thursday, December 18, 2014 7:16 AM, Arnd Bergmann wrote:
> > > On Wednesday 17 December 2014 11:34:45 Gabriel FERNANDEZ wrote:
> > > > ST sti SoCs PCIe IPs are built around DesignWare IP Core.
> > > > But in these SoCs PCIe IP doesn't support IO.
> > I cannot understand how ST sti SoCs PCIe IP does not support I/O.
> > As far as I know, it cannot be selected by the 'parameter'.
> > Then, H/W engineers dropped out the I/O control logic?
> >
> > > >
> > > > To support this, add setup_bus() to pcie_host_ops.
> >
> >
> > > >
> > > > Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
> > > > Signed-off-by: Gabriel Fernandez <gabriel.fernandez@xxxxxxxxxx>
> > >
> > > The dw-pcie driver should be able to tell whether the device has
> > > an I/O space or not, and do the right thing based on that. Don't
> > > add an implementation specific callback for that.
> >
> > I agree with Arnd's opinion.
> >
> > In addition, I have one more question.
> > Then, if a device that requires I/O region is connected to
> > PCIe slot of ST sti SoCs PCIe, what will happen?
> > It just prints error messages?
> >
> >
> Arnd i
> n other post mention to add an empty I/O space to workaround lack of I/O
> port access.
> Is it the right thing to do ?
> â
> http://lists.infradead.org/pipermail/linux-arm-kernel/2014-November/299623.html
> 

Good question. Given the latest development, I'd feel tempted to
try moving the entire pcie-designware driver to use the generic probing
that bypassses pci_common_init_dev(). Rob Herring posted a patch
for the versatile PCI driver, you could try doing the same thing
here, see http://permalink.gmane.org/gmane.linux.kernel.pci/30346.

I think that would completely avoid this problem, and also help everyone
that wants to use this driver on arm64.

	Arnd
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