On 22 October 2015 at 00:51, Scott Wood [off-list ref] wrote:

On Wed, 2015-10-21 at 08:44 -0500, Rob Herring wrote:

quoted

On Wed, Oct 21, 2015 at 12:54 AM, Scott Wood [off-list ref]
wrote:

quoted

On Mon, 2015-09-21 at 16:03 +0200, Tomeu Vizoso wrote:

quoted

Instead of trying to match and probe platform and AMBA devices right
after each is registered, delay their probes until device_initcall_sync.

This means that devices will start probing once all built-in drivers
have registered, and after all platform and AMBA devices from the DT
have been registered already.

This allows us to prevent deferred probes by probing dependencies on
demand.

Signed-off-by: Tomeu Vizoso <tomeu.vizoso-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org>
---

Changes in v4:
- Also defer probes of AMBA devices registered from the DT as they can
  also request resources.

 drivers/of/platform.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

This breaks arch/powerpc/sysdev/fsl_pci.c.  The PCI bus is an OF platform
device, and it must be probed before pcibios_init() which is a
subsys_initcall(), or else the PCI bus never gets scanned.

Thanks for the report. This is probably getting dropped, but it could
be disabled for PPC.

I don't think that adding another arbitrary arch difference would be the
right solution.

I think Rob meant temporarily disable it while things get fixed. At
least, I don't see any reason why PPC wouldn't benefit from this
series.

Regards,

Tomeu

quoted

Any plans to fix this and make PCI hosts hotplugable? For the scanning
part, generally the host controller drivers are responsible for
scanning their bus now.

Scanning from the host controller driver seems like a reasonable goal, though

it'd take a bit of digging to extract whatever other things fsl_pci may
depend on from the common PPC PCI code, in particular the various things that

pcibios_resource_survey() does after all PCI buses have been scanned.

There's also check_swiotlb_enabled(), another subsys_initcall, which frees
the swiotlb memory if ppc_swiotlb_enable hasn't been set.  The PCI host
controller probe sets ppc_swiotlb_enable if it wasn't able to create an
inbound mapping for all RAM.  Even if we were to change that to a later
initcall, there's nothing later than late_initcall that we could use.

-Scott

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