Re: [RFT PATCH v3] PCI: move pci_read_bridge_bases to the generic PCI layer

[Guenter Roeck <linux@roeck-us.net>]

On 07/22/2015 02:14 AM, Lorenzo Pieralisi wrote:
> Bjorn, Guenter,
>
> On Thu, Jul 09, 2015 at 11:59:16AM +0100, Lorenzo Pieralisi wrote:
>> When a PCI bus is scanned, upon PCI bridge detection the kernel
>> has to read the bridge registers to set-up its resources so that
>> the PCI resource hierarchy can be validated properly.
>>
>> Most if not all architectures read PCI bridge registers in the
>> pcibios_fixup_bus hook, that is called by the PCI generic layer
>> whenever a PCI bus is scanned.
>>
>> Since pci_read_bridge_bases is an arch agnostic operation (and it
>> is carried out on all architectures) it can be moved to the generic
>> PCI layer in order to consolidate code and remove the respective
>> calls from the architectures back-ends.
>>
>> The PCI_PROBE_ONLY flag is not checked before calling
>> pci_read_bridge_buses in the generic layer since reading the bridge
>> bases is not related to resources assignment; this implies that it
>> can be carried out safely on PCI_PROBE_ONLY systems too and should
>> not affect architectures (alpha, mips) that check the PCI_PROBE_ONLY
>> flag before reading the bridge bases.
>>
>> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>> Cc: Ralf Baechle <ralf@linux-mips.org>
>> Cc: James E.J. Bottomley <jejb@parisc-linux.org>
>> Cc: Michael Ellerman <mpe@ellerman.id.au>
>> Cc: Bjorn Helgaas <bhelgaas@google.com>
>> Cc: Richard Henderson <rth@twiddle.net>
>> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> Cc: David Howells <dhowells@redhat.com>
>> Cc: Russell King <linux@arm.linux.org.uk>
>> Cc: Tony Luck <tony.luck@intel.com>
>> Cc: David S. Miller <davem@davemloft.net>
>> Cc: Ingo Molnar <mingo@redhat.com>
>> Cc: Guenter Roeck <linux@roeck-us.net>
>> Cc: Michal Simek <monstr@monstr.eu>
>> Cc: Chris Zankel <chris@zankel.net>
>> ---
>> v2->v3:
>>
>> - Dropped RFC status
>> - Removed bridge resources claiming from pci_read_bridge_bases()
>
> What do you want me to do with this patch ? I removed the resource
> claiming - ie the only controversial bit, I can only test on
> arm64, I would like to make some progress on this otherwise
> I will have to add the bridge bases read to arm64 pcibios_fixup_bus()
> and be done with this.
>

Lorenzo,

please give me a few days to test it. I was out on vacation for
the last two weeks, and I am still struggling to get my test systems
back to a working state.

Thanks,
Guenter