linux-kernel - Re: [PATCH 5/5 v5] irqchip: Ingenic: Add process for more than one irq at the same time.

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Date:   Sun, 06 Oct 2019 02:15:05 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Zhou Yanjie <zhouyanjie@...o.com>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, paul.burton@...s.com,
        gregkh@...uxfoundation.org, jason@...edaemon.net, syq@...ian.org,
        marc.zyngier@....com, rfontana@...hat.com, armijn@...ldur.nl,
        allison@...utok.net
Subject: Re: [PATCH 5/5 v5] irqchip: Ingenic: Add process for more than one
 irq at the same time.



Le mer., oct. 2, 2019 at 19:25, Zhou Yanjie <zhouyanjie@...o.com> a 
écrit :
> Add process for the situation that more than one irq is coming to
> a single chip at the same time. The original code will only respond
> to the lowest setted bit in JZ_REG_INTC_PENDING, and then exit the
> interrupt dispatch function. After exiting the interrupt dispatch
> function, since the second interrupt has not yet responded, the
> interrupt dispatch function is again entered to process the second
> interrupt. This creates additional unnecessary overhead, and the
> more interrupts that occur at the same time, the more overhead is
> added. The improved method in this patch is to check whether there
> are still unresponsive interrupts after processing the lowest
> setted bit interrupt. If there are any, the processing will be
> processed according to the bit in JZ_REG_INTC_PENDING, and the
> interrupt dispatch function will be exited until all processing
> is completed.
> 
> Signed-off-by: Zhou Yanjie <zhouyanjie@...o.com>

Looks good to me.

Reviewed-by: Paul Cercueil <paul@...pouillou.net>


> ---
>  drivers/irqchip/irq-ingenic.c | 17 +++++++++++------
>  1 file changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-ingenic.c 
> b/drivers/irqchip/irq-ingenic.c
> index 06ab3ad..c1be3d5 100644
> --- a/drivers/irqchip/irq-ingenic.c
> +++ b/drivers/irqchip/irq-ingenic.c
> @@ -1,7 +1,7 @@
>  // SPDX-License-Identifier: GPL-2.0-or-later
>  /*
>   *  Copyright (C) 2009-2010, Lars-Peter Clausen <lars@...afoo.de>
> - *  JZ4740 platform IRQ support
> + *  Ingenic XBurst platform IRQ support
>   */
> 
>  #include <linux/errno.h>
> @@ -37,18 +37,23 @@ static irqreturn_t intc_cascade(int irq, void 
> *data)
>  	struct ingenic_intc_data *intc = irq_get_handler_data(irq);
>  	struct irq_domain *domain = intc->domain;
>  	struct irq_chip_generic *gc;
> -	uint32_t irq_reg;
> +	uint32_t pending;
>  	unsigned i;
> 
>  	for (i = 0; i < intc->num_chips; i++) {
>  		gc = irq_get_domain_generic_chip(domain, i * 32);
> 
> -		irq_reg = irq_reg_readl(gc, JZ_REG_INTC_PENDING);
> -		if (!irq_reg)
> +		pending = irq_reg_readl(gc, JZ_REG_INTC_PENDING);
> +		if (!pending)
>  			continue;
> 
> -		irq = irq_find_mapping(domain, __fls(irq_reg) + (i * 32));
> -		generic_handle_irq(irq);
> +		while (pending) {
> +			int bit = __fls(pending);
> +
> +			irq = irq_find_mapping(domain, bit + (i * 32));
> +			generic_handle_irq(irq);
> +			pending &= ~BIT(bit);
> +		}
>  	}
> 
>  	return IRQ_HANDLED;
> --
> 2.7.4
> 
>