Thread (12 messages) 12 messages, 4 authors, 2014-10-30

Re: I2C OF IRQ parsing issue due to probe ordering

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: 2014-10-30 13:12:36
Also in: linux-i2c, lkml

Hi Thierry,

On Thursday 30 October 2014 14:02:09 Thierry Reding wrote:
On Thu, Oct 30, 2014 at 02:53:42PM +0200, Laurent Pinchart wrote:
quoted
On Monday 27 October 2014 13:58:19 Wolfram Sang wrote:
quoted
quoted
The i2c@e6520000 node is probed before the gpio@e6051000 node. The
of_i2c_register_devices() function tries to register all children,
including hdmi@39. It tries to parse and map the I2C client IRQ by
calling irq_of_parse_and_map(), which returns 0 as the interrupt
controller isn't probed yet. The adv7511 driver later probes the
hdmi@39
device and gets client->irq set to 0.
I've got this strange feeling of deja vu... Ah, here: Thierry Reding
quoted
tackled this problem a year ago. His series:
Thanks for the pointer.
quoted
https://lkml.org/lkml/2013/9/16/111 (of/irq: Defer interrupt reference
resolution)

He did a V2 (which never made it to the i2c list). Seems like the first
two patches made it and the rest got stalled without discussion?

https://lkml.org/lkml/2013/9/18/216

Adding Thierry to the queue. Maybe he can bring some light to what
happened to his series.
That's exactly what I need :-) Thierry, do you plan to respin the series ?
Not really. Like I said in my reply to Wolfram, a different set of
patches was merged subsequently to solve this issue for platform
devices, which makes my patchset mostly obsolete. But I think the
solution that you proposed would work well if you do:

-		int irq = irq_of_parse_and_map(dev->of_node, 0);
+		int irq = of_irq_get(dev->of_node, 0);

And then changing irq_create_of_mapping() should no longer be necessary.
It looks like it would work, yes. I'll test it and will resubmit my patch.
I still think it's kind of lame to handle -EPROBE_DEFER specially as was
done in of_irq_get(), but given how worried people were about the more
invasive changes needed to propagate the correct error code all the way
up it seems like that's as good as it's going to get.
-- 
Regards,

Laurent Pinchart
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