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SubjectRe: [PATCH 1/4] Irqchip: Ingenic: Change interrupt handling form cascade to chained_irq.
On Sat, 26 Jan 2019 15:38:40 +0000,
Zhou Yanjie <zhouyanjie@zoho.com> wrote:
>
> The interrupt handling method is changed from old-style cascade to
> chained_irq which is more appropriate. Also, it can process the
> corner situation that more than one irq is coming to a single
> chip at the same time.
>
> Signed-off-by: Zhou Yanjie <zhouyanjie@zoho.com>
> ---
> drivers/irqchip/irq-ingenic.c | 49 ++++++++++++++++++++++---------------------
> 1 file changed, 25 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/irqchip/irq-ingenic.c b/drivers/irqchip/irq-ingenic.c
> index 2ff0898..2713ec4 100644
> --- a/drivers/irqchip/irq-ingenic.c
> +++ b/drivers/irqchip/irq-ingenic.c
> @@ -1,16 +1,7 @@
> +// SPDX-License-Identifier: GPL-2.0
> /*
> * Copyright (C) 2009-2010, Lars-Peter Clausen <lars@metafoo.de>
> - * JZ4740 platform IRQ support
> - *
> - * This program is free software; you can redistribute it and/or modify it
> - * under the terms of the GNU General Public License as published by the
> - * Free Software Foundation; either version 2 of the License, or (at your
> - * option) any later version.
> - *
> - * You should have received a copy of the GNU General Public License along
> - * with this program; if not, write to the Free Software Foundation, Inc.,
> - * 675 Mass Ave, Cambridge, MA 02139, USA.
> - *
> + * Ingenic XBurst platform IRQ support
> */
>
> #include <linux/errno.h>
> @@ -19,6 +10,7 @@
> #include <linux/interrupt.h>
> #include <linux/ioport.h>
> #include <linux/irqchip.h>
> +#include <linux/irqchip/chained_irq.h>
> #include <linux/irqchip/ingenic.h>
> #include <linux/of_address.h>
> #include <linux/of_irq.h>
> @@ -41,22 +33,35 @@ struct ingenic_intc_data {
> #define JZ_REG_INTC_PENDING 0x10
> #define CHIP_SIZE 0x20
>
> -static irqreturn_t intc_cascade(int irq, void *data)
> +static void ingenic_chained_handle_irq(struct irq_desc *desc)
> {
> - struct ingenic_intc_data *intc = irq_get_handler_data(irq);
> - uint32_t irq_reg;
> + struct ingenic_intc_data *intc = irq_desc_get_handler_data(desc);
> + struct irq_chip *chip = irq_desc_get_chip(desc);
> + bool have_irq = false;
> + u32 pending;
> unsigned i;
>
> + chained_irq_enter(chip, desc);
> for (i = 0; i < intc->num_chips; i++) {
> - irq_reg = readl(intc->base + (i * CHIP_SIZE) +
> + pending = readl(intc->base + (i * CHIP_SIZE) +
> JZ_REG_INTC_PENDING);
> - if (!irq_reg)
> + if (!pending)
> continue;
>
> - generic_handle_irq(__fls(irq_reg) + (i * 32) + JZ4740_IRQ_BASE);
> + have_irq = true;
> + while (pending) {
> + int bit = __ffs(pending);

So 'bit' is the least significant bit in the pending word,

> +
> + generic_handle_irq(__fls(pending) + (i * 32) +

and here you handle the *most significant* bit,

> + JZ4740_IRQ_BASE);
> + pending &= ~BIT(bit);

yet it is the least significant bit that you clear. I am tempted to
say that you have never tested this code with more than a single
interrupt.

Thanks,

M.

--
Jazz is not dead, it just smell funny.

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