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From: Thomas Gleixner <tglx@linutronix.de>
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To: Richard Clark <richard.xnu.clark@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
 torvalds@linux-foundation.org
Subject: Re: [PATCH] irq: fix the interrupt trigger type override issue
In-Reply-To: <ZtbA5Adh2acTExYq@den-build>
References: <ZtUuYXSq8g2Mphuq@den-build> <87r0a27blv.ffs@tglx>
 <CAJNi4rPm2N=_H7LjT3X3_b2-UVZP+EEOw-ztwBwWBs=vMtfYQQ@mail.gmail.com>
 <877cbu7596.ffs@tglx>
 <CAJNi4rPooS82fB+6FditywXTga00JbGoFM6MR8P7U3s7mdbJCg@mail.gmail.com>
 <87y14a5dcq.ffs@tglx> <ZtbA5Adh2acTExYq@den-build>
Date: Tue, 03 Sep 2024 12:18:08 +0200
Message-ID: <87frqh82hr.ffs@tglx>
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Richard!

On Tue, Sep 03 2024 at 15:55, Richard Clark wrote:
> On Mon, Sep 02, 2024 at 04:39:33PM +0200, Thomas Gleixner wrote:
>> So the mapping and the interrupt allocation persist even if nothing uses
>> them. What a waste.
>>
> I checked the code and found that it's not the kernel to create the mapping,
> it's by the driver calling platform_get_irq(...)/of_irq_get(...) to
> create.

:)
 
> Ah, the mapping is created from of_irq_get(...) by driver, the kernel also
> provides the mapping teardown interface - irq_dispose_mapping.
> IMO, the right way for the driver is:
> 	1) driver calls of_irq_get() to get the irq and create the mapping
> 	2) driver *should* call irq_dispose_mapping() as the teardown of step 1.
> 	3) free_irq is the teardown of the request_irq to free the irq and
> 	   its action.

Correct.

Thanks,

        tglx