linux-kernel - Re: [PATCH] irqdomain: handle the per-CPU irq trigger type settings

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Date:   Fri, 10 Mar 2017 11:35:53 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     gengdongjiu <gengdongjiu@...wei.com>
cc:     jason@...edaemon.net, benh@...nel.crashing.org,
        linux-kernel@...r.kernel.org, zhanghaibin7@...wei.com,
        huangshaoyu@...wei.com
Subject: Re: [PATCH] irqdomain: handle the per-CPU irq trigger type
 settings


On Fri, 10 Mar 2017, gengdongjiu wrote:

>     when devices parse and map an per-cpu interrupt into linux virq space
>     using irq_of_parse_and_map API, it will always be failed if needs to set
>     the specified irq trigger type, because irq_set_irq_type is only for 1-N
>     mode interrupt source, not for per-cpu interrupt source. so handle per-cpu
>     IRQs for this failure.

Please format your changelogs proper into sections:

1) Context

2) Problem

3) Solution

Writing one big lump of a sentence is just unreadable.

Aside of that:

1) No indentation of the changelog
2) Sentences start with upper case letters
3) Function references want () after the function name

Aside

> 
>     Signed-off-by: Dongjiu Geng <gengdongjiu@...wei.com>
>                    Zhanghai bin <zhanghaibin7@...wei.com>

That SOB is bogus.

> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
> index 9fd618d..8116cf2 100755
> --- a/kernel/irq/irqdomain.c
> +++ b/kernel/irq/irqdomain.c
> @@ -542,8 +542,16 @@ unsigned int irq_create_of_mapping(struct of_phandle_args *irq_data)
> 
>         /* Set type if specified and different than the current one */
>         if (type != IRQ_TYPE_NONE &&
> -           type != irq_get_trigger_type(virq))
> -               irq_set_irq_type(virq, type);
> +           type != irq_get_trigger_type(virq)) {
> +               int ret = 0;
> +               struct irq_data *irq_data = irq_get_irq_data(virq);
> +
> +               ret = irq_set_irq_type(virq, type);
> +
> +                /* Handle per-cpu IRQ: just save type in irq_data */
> +               if (-EINVAL == ret && irq_data)
> +                       irqd_set_trigger_type(irq_data, type);

This is completely broken. That stores a trigger type for any interrupt if
the set type function fails.

You fail to explain

    - WHY irq_set_irq_type() fails for these per cpu interrupts
    
    - WHY storing the type in irqdata solves anything

    - WHAT sets the type in the actual interrupt hardware

That information should be in the changelog ....

Thanks,

	tglx