linux-kernel - Re: [PATCH v6 02/11] irqchip: loongson-liointc: Workaround LPC IRQ Errata

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Date:   Wed, 25 Mar 2020 09:52:26 +0800
From:   Huacai Chen <chenhc@...ote.com>
To:     Jiaxun Yang <jiaxun.yang@...goat.com>
Cc:     "open list:MIPS" <linux-mips@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Allison Randal <allison@...utok.net>,
        LKML <linux-kernel@...r.kernel.org>, devicetree@...r.kernel.org
Subject: Re: [PATCH v6 02/11] irqchip: loongson-liointc: Workaround LPC IRQ Errata

Hi, Jiaxun,

On Tue, Mar 24, 2020 at 11:39 PM Jiaxun Yang <jiaxun.yang@...goat.com> wrote:
>
> The 1.0 version of that controller has a bug that status bit
> of LPC IRQ sometimes doesn't get set correctly.
>
> So we can always blame LPC IRQ when spurious interrupt happens
> at the parent interrupt line which LPC IRQ supposed to route
> to.
>
> Co-developed-by: Huacai Chen <chenhc@...ote.com>
> Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
> ---
>  drivers/irqchip/irq-loongson-liointc.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/irqchip/irq-loongson-liointc.c b/drivers/irqchip/irq-loongson-liointc.c
> index 8b6d7b8ddaca..d5054e90eab8 100644
> --- a/drivers/irqchip/irq-loongson-liointc.c
> +++ b/drivers/irqchip/irq-loongson-liointc.c
> @@ -32,6 +32,8 @@
>
>  #define LIOINTC_SHIFT_INTx     4
>
> +#define LIOINTC_ERRATA_IRQ     10
> +
>  struct liointc_handler_data {
>         struct liointc_priv     *priv;
>         u32                     parent_int_map;
> @@ -41,6 +43,7 @@ struct liointc_priv {
>         struct irq_chip_generic         *gc;
>         struct liointc_handler_data     handler[LIOINTC_NUM_PARENT];
>         u8                              map_cache[LIOINTC_CHIP_IRQ];
> +       bool                            have_lpc_irq_errata;
Maybe has_lpc_irq_errata?

>  };
>
>  static void liointc_chained_handle_irq(struct irq_desc *desc)
> @@ -54,8 +57,14 @@ static void liointc_chained_handle_irq(struct irq_desc *desc)
>
>         pending = readl(gc->reg_base + LIOINTC_REG_INTC_STATUS);
>
> -       if (!pending)
> -               spurious_interrupt();
> +       if (!pending) {
> +               /* Always blame LPC IRQ if we have that bug and LPC IRQ is enabled */
> +               if (handler->priv->have_lpc_irq_errata &&
> +                       (handler->parent_int_map & ~gc->mask_cache & BIT(LIOINTC_ERRATA_IRQ)))
> +                       pending = BIT(LIOINTC_ERRATA_IRQ);
> +               else
> +                       spurious_interrupt();
> +       }
>
>         while (pending) {
>                 int bit = __ffs(pending);
> @@ -164,6 +173,9 @@ int __init liointc_of_init(struct device_node *node,
>                 goto out_iounmap;
>         }
>
> +       if (of_device_is_compatible(node, "loongson,liointc-1.0"))
> +               priv->have_lpc_irq_errata = true;
> +
>         sz = of_property_read_variable_u32_array(node, "loongson,parent_int_map",
>                                                 &of_parent_int_map[0], LIOINTC_NUM_PARENT,
>                                                 LIOINTC_NUM_PARENT);
> --
> 2.26.0.rc2
>
>

Regards,
Huacai Chen