Re: [PATCH] [RFC] OF: probe order dependency aware of_platform_populate

[Rob Herring <robherring2-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Wed, Apr 15, 2015 at 9:17 AM, Peter Hurley <peter-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org> wrote:
> On 04/08/2015 09:40 AM, Rob Herring wrote:
>> This doesn't sound right. It ignores failures because platform_get_irq
>> will parse the interrupts when called rather than just using the
>> resource struct and will return EPROBE_DEFER if the irq resource is
>> not ready. We left the of_device_alloc code in to be safe, but we
>> should be able to remove it.
>
> This brings up a couple of points which are plaguing the serial drivers:
> 1. Is platform_get_irq() now required to properly obtain the mapped irq
>    for DT-aware drivers? IOW, is platform_get_resource(IORESOURCE_IRQ)
>    broken? Will it be if the of_device_alloc() code is removed?

Yes, and that is why we left the of_device_alloc code now that I
remember. platform_get_irq will first have to be used everywhere to
remove the code in of_device_alloc. It also has to be used for
deferred probe to work (if it is irq's you need to wait for).

> 2. Should DT-specific drivers not be using irq_of_parse_and_map()?
>    On probe failure irq_dispose_mapping() will be junking the mapping,
>    thus invalidating the irq assignment in the platform resource table,
>    which breaks platform drivers which might otherwise probe successfully.

Generally no, they should not use irq_of_parse_and_map as we want
drivers to work with platform_data, DT, ACPI, or Bob's Firmware
Interface. I think most users are PPC drivers which don't have so much
of the probe ordering problems.

Rob
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