linux-kernel - Re: [PATCH v2 07/20] clocksource/drivers/vf-pit: Allocate the struct timer at init time

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Message-ID: <7e80eaf4-4d78-420c-82c6-0604a5180f71@oss.nxp.com>
Date: Mon, 4 Aug 2025 13:02:38 +0300
From: Ghennadi Procopciuc <ghennadi.procopciuc@....nxp.com>
To: Daniel Lezcano <daniel.lezcano@...aro.org>, tglx@...utronix.de
Cc: S32@....com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 07/20] clocksource/drivers/vf-pit: Allocate the struct
 timer at init time

On 8/4/2025 12:12 PM, Daniel Lezcano wrote:
> On 01/08/2025 09:33, Ghennadi Procopciuc wrote:
>> On 7/30/2025 11:27 AM, Daniel Lezcano wrote:
>>
>> [...]
>>
> 
> [ ... ]
> 
>>> +    ret = -EINVAL;
>>>       irq = irq_of_parse_and_map(np, 0);
>>> -    if (irq <= 0)
>>> -        return -EINVAL;
>>> +    if (irq <= 0) {
>>> +        pr_err("Failed to irq_of_parse_and_map\n");
>>> +        goto out_iounmap;
>>> +    }
>>>         pit_clk = of_clk_get(np, 0);
>>> -    if (IS_ERR(pit_clk))
>>> -        return PTR_ERR(pit_clk);
>>> +    if (IS_ERR(pit_clk)) {
>>> +        ret = PTR_ERR(pit_clk);
>>> +        goto out_iounmap;
>>
>> This does not revert the use of irq_of_parse_and_map. In my opinion, it
>> should be explicitly reverted as part of the cleanup phase by calling
>> irq_of_parse_and_map.
> 
> AFAICT, it does not make sense to undo irq_of_parse_and_map() and there
> is no revert function for that.
> 
> However, calling free_irq as commented in patch 20/20 makes sense.
> 
> 

I noticed that irq_of_parse_and_map internally calls both
of_irq_parse_one and irq_create_of_mapping. While the former does not
have a corresponding revert function, the latter can be reversed using
irq_dispose_mapping.

Examples:
    drivers/char/ipmi/ipmi_powernv.c
    drivers/clocksource/timer-microchip-pit64b.c
    drivers/crypto/amcc/crypto4xx_core.c
    drivers/memory/fsl_ifc.c

-- 
Regards,
Ghennadi