linux-kernel - Re: [PATCH 2/4] irqchip: Add IRQCHIP_DECLARE

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Date:   Fri, 27 Jan 2017 10:13:07 -0800
From:   Andrey Smirnov <andrew.smirnov@...il.com>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     Andrey Yurovsky <yurovsky@...il.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/4] irqchip: Add IRQCHIP_DECLARE_DRIVER macro

+Cc linux-kernel@...r.kernel.org since I messed up original distribution list

On Fri, Jan 27, 2017 at 12:51 AM, Marc Zyngier <marc.zyngier@....com> wrote:
> On 26/01/17 21:56, Andrey Smirnov wrote:
>> Add IRQCHIP_DECLARE_DRIVER macro to allow having driver code that both
>> registers irqchip and a platform driver. Based on analogous code of
>> CLK_OF_DECLARE_DRIVER.
>>
>> Cc: yurovsky@...il.com
>> Cc: Shawn Guo <shawnguo@...nel.org>
>> Cc: Thomas Gleixner <tglx@...utronix.de>
>> Cc: Jason Cooper <jason@...edaemon.net>
>> Cc: Marc Zyngier <marc.zyngier@....com>
>> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
>> ---
>>  include/linux/irqchip.h | 16 ++++++++++++++++
>>  1 file changed, 16 insertions(+)
>>
>> diff --git a/include/linux/irqchip.h b/include/linux/irqchip.h
>> index 89c34b2..611e8cc 100644
>> --- a/include/linux/irqchip.h
>> +++ b/include/linux/irqchip.h
>> @@ -27,6 +27,22 @@
>>  #define IRQCHIP_DECLARE(name, compat, fn) OF_DECLARE_2(irqchip, name, compat, fn)
>>
>>  /*
>> + * Use this macro when you have a driver that requires two
>> + * initialization routines, one at IRQCHIP_DECLARE, and one at
>> + * platform device probe
>> + */
>> +#define IRQCHIP_DECLARE_DRIVER(name, compat, fn)                     \
>> +     static int __init                                               \
>> +     name##_of_irqchip_init_driver(struct device_node *np,           \
>> +                                   struct device_node *parent)       \
>> +     {                                                               \
>> +             of_node_clear_flag(np, OF_POPULATED);                   \
>> +             return fn(np, parent);                                  \
>> +     }                                                               \
>> +     OF_DECLARE_2(irqchip, name, compat, name##_of_irqchip_init_driver)
>> +
>> +
>> +/*
>>   * This macro must be used by the different irqchip drivers to declare
>>   * the association between their version and their initialization function.
>>   *
>>
>
> Why do we need this new macro? What problem does it solve that would not
> be solved by having proper dependency tracking?

The problem that I was trying to solve was trying to associate a
platform device with a DT-node that had a IRQCHIP_DECLARE declared for
it. After a bit of digging around the codebase I found
CLK_OF_DECLARE_DRIVER which seemed to exist to solve exactly the same
kind of problem I was having so I took it as "inspiration" and created
IRQCHIP_DECLARE_DRIVER.

I am not sure what you mean by "proper dependency tracking"(most
likely due to my ignorance), can you point me to a concrete example or
explain what you mean a bit more?

I'll be more happy to change the code and drop this macro if there's a
better way to solve my original problem.

Thanks you,
Andrey Smirnov