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

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Message-ID: <20140418205510.GB21823@atomide.com>
Date:	Fri, 18 Apr 2014 13:55:11 -0700
From:	Tony Lindgren <tony@...mide.com>
To:	Thierry Reding <thierry.reding@...il.com>
Cc:	Rob Herring <robherring2@...il.com>,
	Greg KH <gregkh@...uxfoundation.org>,
	Arnd Bergmann <arnd@...db.de>,
	Grant Likely <grant.likely@...aro.org>,
	Paul Walmsley <paul@...an.com>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] of/platform: Fix no irq domain found errors when
 populating interrupts

* Thierry Reding <thierry.reding@...il.com> [140411 11:46]:
> On Thu, Apr 10, 2014 at 07:29:36PM -0500, Rob Herring wrote:
> > On Thu, Apr 10, 2014 at 4:38 PM, Tony Lindgren <tony@...mide.com> 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@...02030 !
> > > ------------[ 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
> > 
> > There is a newer solution here which Grant seemed happier with:
> > 
> > http://lkml.iu.edu/hypermail/linux/kernel/1403.2/03666.html
> 
> I wonder why Grant seems to be happier with that solution than with my
> original proposal. That new solution does essentially the same thing.
> One of the main issues raised during review of my original proposal was
> that it had to modify the core, but this new solution does that as well.
> 
> Another thing that people weren't happy about was that my solution was
> more intrusive because it required a bunch of changes to the of_irq_*()
> helpers to make them propagate a proper error code. The new solution
> doesn't do that, but instead works around the lack of proper error
> propagation by trying to find an IRQ domain (which the of_irq_*()
> helpers will do anyway).

Yeah the problem I see with the patches above is that there's
nothing wrong with the irq subsystem. Replied along those lines to
the thread above.

Cheers,

Tony
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