linux-kernel - Re: Problems with commit 9ec36cafe4 (of/irq: do irq resolution in platform_get

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Message-ID: <CAL_JsqK9bcb9LKRM_S8R0YqcNzuBnW1fhwEsAYYxfOEdmmhKtQ@mail.gmail.com>
Date:	Tue, 17 Jun 2014 16:39:13 -0500
From:	Rob Herring <robh@...nel.org>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>
Subject: Re: Problems with commit 9ec36cafe4 (of/irq: do irq resolution in
 platform_get_irq) and mfd client devices

On Tue, Jun 17, 2014 at 3:29 PM, Guenter Roeck <linux@...ck-us.net> wrote:
> On Tue, Jun 17, 2014 at 03:08:24PM -0500, Rob Herring wrote:
>> On Tue, Jun 17, 2014 at 1:10 PM, Guenter Roeck <linux@...ck-us.net> wrote:
>> > Hi,
>> >
>> > I have an mfd master and client drivers on a system which has devicetree
>> > enabled. The mfd master driver passes interrupts to the clients using
>> > mfd cells and 'struct resource'. The client driver is a platform driver
>> > which retrieves the irq using platform_get_irq().
>> >
>> > After commit 9ec36cafe (of/irq: do irq resolution in platform_get_irq),
>> > this code no longer works. This is because platform_get_irq() does no
>> > longer call platform_get_resource() if OF is enabled and if dev->of_node
>> > is not NULL (it is not NULL because there is other [static] information
>> > which is passed to the client with devicetree data).
>> >
>> > Any idea how to solve this problem ? How do I now pass a virtual interrupt
>> > from an mfd master to its clients if devicetree is enabled ?
>>
>> The node ptr points to the MFD node or a child node? If there are
>> child nodes in DT, then why not define interrupts there too? If there
>> are not child nodes, then perhaps the child drivers should not have DT
>> knowledge.
>>
> There is a whole bunch of secondary data in the child's dt node.
> One of the child/client drivers is an i2c controller with attached
> i2c muxes and several i2c devices, another is a gpio controller
> with a large number of gpio pins which itself acts as interrupt
> controller.

Then why not put interrupt data into the child nodes?

>> Does it fail to get an interrupt or gets the parent interrupt instead?
>>
> It fails to get an interrupt and returns -EINVAL.
>
>> We could probably make an error fall-back to looking at resources. Or
>> try to get irq from resources first, then call of_irq_get.
>>
> I submitted a patch implementing the first approach a few minutes ago.
> That fixes the problem for me. Not sure if that is the right solution
> though, as it doesn't handle -EPROBE_DEFER. Let me know when you see
> the patch if there is a better way to handle it (maybe abort with
> -EPROBE_DEFER if of_irq_get returns it would do).

Humm, don't see it. In any case, you would need to fall back only if
the error is not EPROBE_DEFER.

Rob
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