Re: [PATCH] of/platform: Fix no irq domain found errors when populating interrupts

[Thierry Reding <thierry.reding@gmail.com>]

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On Fri, Apr 11, 2014 at 10:20:28AM +0100, Russell King - ARM Linux wrote:
> On Thu, Apr 10, 2014 at 02:38:09PM -0700, Tony Lindgren wrote:
> > Currently we get the following kind of errors if we try to use interrupt
> > phandles to irqchips that have not yet initialized:
> > 
> > irq: no irq domain found for /ocp/pinmux@48002030 !
> > ------------[ cut here ]------------
> > WARNING: CPU: 0 PID: 1 at drivers/of/platform.c:171 of_device_alloc+0x144/0x184()
> > Modules linked in:
> > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.12.0-00038-g42a9708 #1012
> > (show_stack+0x14/0x1c)
> > (dump_stack+0x6c/0xa0)
> > (warn_slowpath_common+0x64/0x84)
> > (warn_slowpath_null+0x1c/0x24)
> > (of_device_alloc+0x144/0x184)
> > (of_platform_device_create_pdata+0x44/0x9c)
> > (of_platform_bus_create+0xd0/0x170)
> > (of_platform_bus_create+0x12c/0x170)
> > (of_platform_populate+0x60/0x98)
> > 
> > This is because we're wrongly trying to populate resources that are not yet
> > available. It's perfectly valid to create irqchips dynamically, so let's
> > fix up the issue by populating the interrupt resources at the driver probe
> > time instead.
> > 
> > Note that at least currently we cannot dynamically allocate the resources as bus
> > specific code may add legacy resources with platform_device_add_resources()
> > before the driver probe. At least omap_device_alloc() currently relies on
> > num_resources to determine if legacy resources should be added. Some of these
> > will clear automatically when mach-omap2 boots with DT only, but there are
> > probably other places too where platform_device_add_resources() modifies
> > things before driver probe.
> > 
> > This patch was discussed quite a bit earlier, but so far it seems we don't
> > have any better options to fix the problem. For the earlier discussion,
> > please see:
> > 
> > https://lkml.org/lkml/2013/11/22/520
> > 
> > The addition of of_platform_probe() is based on patches posted earlier by
> > Thierry Reding <thierry.reding@gmail.com>.
> > 
> > Signed-off-by: Tony Lindgren <tony@atomide.com>
> 
> So what happens if a device driver probe function:
> 
> - creates a new platform device
> - copies the resources from the original to the new device
> - copies the of_node from the original to the new device
> - registers the new device
> 
> Yes, it's broken (because it can result in the same driver being re-probed
> by the new device) but we *do* have stuff in the kernel tree which does
> this.

From what I can tell the only clean solution would be to allow the OF
functions to properly propagate errors. My earlier attempt was exactly
that, but was deemed too invasive.

But that doesn't really solve the case you describe above either. So I
think the only good generic solution would be for all resources to be
resolved by the driver's .probe() function so that resources aren't
"cached" in the device node.

Thierry

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