linux-kernel - Re: [PATCH V1 3/4] irqchip/loongson-liointc: Fix IRQ trigger polarity

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Message-ID: <4a08b133-4ead-083e-4ddb-519e12a0dad6@xen0n.name>
Date:   Sun, 21 May 2023 18:46:16 +0800
From:   WANG Xuerui <kernel@...0n.name>
To:     Jianmin Lv <lvjianmin@...ngson.cn>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>
Cc:     linux-kernel@...r.kernel.org, loongarch@...ts.linux.dev,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        Huacai Chen <chenhuacai@...ngson.cn>,
        loongson-kernel@...ts.loongnix.cn, stable@...r.kernel.org
Subject: Re: [PATCH V1 3/4] irqchip/loongson-liointc: Fix IRQ trigger polarity

On 2023/5/20 14:38, Jianmin Lv wrote:
> For IRQ controller INT_POLARITY regitser of Loongson-2K CPU

"For the INT_POLARITY register of Loongson-2K series IRQ controller"?

> series, '0' indicates high level or rising edge triggered IRQ,
> '1' indicates low level or falling edge triggered IRQ.

Remove the two "IRQ"s; the topic is "polarity", not "IRQs".

Also please mention the source of this information; I've checked the 
Loongson 2K1000LA User Manual v1.0 and it seems a similar description is 
found in Table 9-2, Section 9.3 (中断寄存器描述 / Description of the Interrupt 
Registers). It mentioned "Intpol_0" and "Intpol_1" but the description 
is consistent with the wording here.

> 
> For Loongson-3A CPU series, setting INT_POLARITY register is not
> supported and writting it has no effect.

Only 3A and not the whole Loongson-3 series?

Also typo: "writing".

> 
> So trigger polarity setting shouled be fixed for Loongson-2K CPU
> series.

The changes seem to be just inversion of the polarity flags. It should 
be correct given your description, and not affect Loongson-3 series 
because it's supposed to behave as noops; it may be better to move the 
explanation regarding Loongson-3 behavior to code comment (e.g. 
somewhere near the definition of LIOINTC_REG_INTC_POL) so it's 
immediately visible to drive-by readers not familiar with LoongArch 
internals, without them having to dig through commit history to see this.

> 
> Fixes: 17343d0b4039 ("irqchip/loongson-liointc: Support to set IRQ type for ACPI path")
> Cc: stable@...r.kernel.org
> Signed-off-by: Chong Qiao <qiaochong@...ngson.cn>
> Signed-off-by: Jianmin Lv <lvjianmin@...ngson.cn>

Again, who's the proper author for this patch? Given the tags it seems 
the author should be Chong Qiao, but I didn't see an Author: line at the 
beginning.

> ---
>   drivers/irqchip/irq-loongson-liointc.c | 8 ++++----
>   1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-loongson-liointc.c b/drivers/irqchip/irq-loongson-liointc.c
> index 8d00a9ad5b00..9a9c2bf048a3 100644
> --- a/drivers/irqchip/irq-loongson-liointc.c
> +++ b/drivers/irqchip/irq-loongson-liointc.c
> @@ -116,19 +116,19 @@ static int liointc_set_type(struct irq_data *data, unsigned int type)
>   	switch (type) {
>   	case IRQ_TYPE_LEVEL_HIGH:
>   		liointc_set_bit(gc, LIOINTC_REG_INTC_EDGE, mask, false);
> -		liointc_set_bit(gc, LIOINTC_REG_INTC_POL, mask, true);
> +		liointc_set_bit(gc, LIOINTC_REG_INTC_POL, mask, false);
>   		break;
>   	case IRQ_TYPE_LEVEL_LOW:
>   		liointc_set_bit(gc, LIOINTC_REG_INTC_EDGE, mask, false);
> -		liointc_set_bit(gc, LIOINTC_REG_INTC_POL, mask, false);
> +		liointc_set_bit(gc, LIOINTC_REG_INTC_POL, mask, true);
>   		break;
>   	case IRQ_TYPE_EDGE_RISING:
>   		liointc_set_bit(gc, LIOINTC_REG_INTC_EDGE, mask, true);
> -		liointc_set_bit(gc, LIOINTC_REG_INTC_POL, mask, true);
> +		liointc_set_bit(gc, LIOINTC_REG_INTC_POL, mask, false);
>   		break;
>   	case IRQ_TYPE_EDGE_FALLING:
>   		liointc_set_bit(gc, LIOINTC_REG_INTC_EDGE, mask, true);
> -		liointc_set_bit(gc, LIOINTC_REG_INTC_POL, mask, false);
> +		liointc_set_bit(gc, LIOINTC_REG_INTC_POL, mask, true);
>   		break;
>   	default:
>   		irq_gc_unlock_irqrestore(gc, flags);

-- 
WANG "xen0n" Xuerui

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