Re: [RFC] ARM/ARM64 PCI_PROBE_ONLY platforms

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

[+ Pratyush, Jingoo, Gabriele]

any comment on this for the designware driver ?

Thanks,
Lorenzo

On Fri, Jan 22, 2016 at 04:28:39PM +0000, Phil Edworthy wrote:
> Hi Lorenzo,
> 
> On 20 January 2016 18:10, Lorenzo Pieralisi wrote:
> > On Wed, Jan 20, 2016 at 11:13:04AM -0500, Sinan Kaya wrote:
> > > On 1/20/2016 11:04 AM, Lorenzo Pieralisi wrote:
> > > > Hi,
> > > >
> > > > I noticed that:
> > > >
> > > > 79953dd22c1d ("PCI: rcar: Remove dependency on ARM-specific struct
> > hw_pci")
> > > > cbce7900598c ("PCI: designware: Make driver arch-agnostic")
> > > >
> > > > added code in the respective host controller drivers to size bridges
> > > > and assign resources only if the PCI_PROBE_ONLY flag is clear, which makes
> > > > me wonder if there exists PCI_PROBE_ONLY set-ups for the respective
> > > > host controllers:
> > > >
> <snip>
>  
> > Resources claiming and assignment should be managed in arch code,
> > not in host controllers specific code, and that's the reason I
> > complained in this RFC about the scattering of PCI_PROBE_ONLY flag
> > checks in host drivers, it is becoming unmanageable (if useful
> > at all on designware and rcar, I would like to know if there are
> > PCI_PROBE_ONLY set-ups probing those host drivers).
> 
> I am pretty sure  there are no rcar set-ups that use PCI_PROBE_ONLY,
> so I am happy for that code to go.
> 
> Thanks
> Phil
> 
> > Does it make the point clearer ?
> > 
> > > > https://patchwork.ozlabs.org/patch/545671/
> > > >
> > > > so unless you really have *existing* set-ups that require it, please
> > > > remove the respective checks from the host controller drivers, this is
> > > > becoming a serious issue, because either:
> > > >
> > > > - we claim resources if and only if PCI_PROBE_ONLY is set
> > > >
> > > > Either like this (to be done for every host controllers and ARM
> > > > bios32):
> > > >
> > > > https://patchwork.ozlabs.org/patch/545670/
> > > >
> > > > or in core ARM/ARM64 code - eg pcibios_fixup_bus() - (to avoid adding a
> > > > resource claiming call in ALL PCI host controllers)
> > > >
> > > > - or we *always* carry out resource claiming regardless of PCI_PROBE_ONLY
> > > >   (but on ARM we can't really do that since PCI FW set-up on most of the
> > > >   platforms is not present)
> > > >
> > > > On PCI_PROBE_ONLY systems resources claiming is mandatory if we want
> > > > to get rid of arches workarounds:
> > >
> > > I'm hoping to see x86 like behavior on ARM64 without any gotchas as
> > > there is nothing special about CPU type when it comes to PCI.
> > 
> > As I said, we must enforce it with ACPI, for DT platforms I am all
> > ears to decide how we can implement it sanely (I think the only way
> > to do it is by claiming the PCI resources on PCI_PROBE_ONLY systems,
> > that's not ideal but it simplifies things a lot).
> > 
> > Thanks,
> > Lorenzo
> > 
> > >
> > > >
> > > > https://patchwork.ozlabs.org/patch/545671/
> > > >
> > > > Comments very appreciated.
> > > >
> > > > Thanks,
> > > > Lorenzo
> > > > --
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> > > >
> > >
> > >
> > > --
> > > Sinan Kaya
> > > Qualcomm Technologies, Inc. on behalf of Qualcomm Innovation Center, Inc.
> > > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux
> > Foundation Collaborative Project
> > >
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