Re: [PATCH v4 2/2] PCI: Rockchip: Add Rockchip PCIe controller support

[Marc Zyngier]

On 01/07/16 02:24, Shawn Lin wrote:
> This patch adds Rockchip PCIe controller support found
> on RK3399 Soc platform.
> 
> Signed-off-by: Shawn Lin <shawn....@rock-chips.com>
> 
> ---

[...]

> +static void rockchip_pcie_legacy_int_handler(struct irq_desc *desc)
> +{
> +     struct irq_chip *chip = irq_desc_get_chip(desc);
> +     struct rockchip_pcie_port *port;
> +     u32 reg;
> +
> +     chained_irq_enter(chip, desc);
> +     port = irq_desc_get_handler_data(desc);
> +
> +     reg = pcie_read(port, PCIE_CLIENT_INT_STATUS);
> +     reg = (reg & ROCKCHIP_PCIE_RPIFR1_INTR_MASK) >>
> +            ROCKCHIP_PCIE_RPIFR1_INTR_SHIFT;
> +     if (reg)
> +             generic_handle_irq(irq_find_mapping(port->irq_domain,
> +                                                 ffs(reg)));

Can't you get multiple pending interrupts at the same time? Here, you
seem to only process one interrupt at a time, which is going to be
pretty inefficient.

How about something like:

        while (reg) {
                int hwirq = ffs(reg);
                int irq;
                
                reg &= ~BIT(hwirq);
                irq = irq_find_mapping(port->irq_domain, hwirq);
                if (irq)
                        generic_handle_irq(irq);
        }

> +     chained_irq_exit(chip, desc);
> +}
> +

Thanks,

        M.
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