linux-kernel - Re: [Patch v5 04/12] irqchip: xilinx: Add support for parent intc

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Message-ID: <32f5f17d-7864-c782-7a6f-03660b7ab055@arm.com>
Date:   Fri, 21 Oct 2016 10:48:15 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Zubair Lutfullah Kakakhel <Zubair.Kakakhel@...tec.com>,
        monstr@...str.eu, ralf@...ux-mips.org, tglx@...utronix.de,
        jason@...edaemon.net, alistair@...ple.id.au,
        mporter@...nel.crashing.org
Cc:     soren.brinkmann@...inx.com, linux-kernel@...r.kernel.org,
        linux-mips@...ux-mips.org, michal.simek@...inx.com,
        linuxppc-dev@...ts.ozlabs.org, mpe@...erman.id.au,
        paulus@...ba.org, benh@...nel.crashing.org
Subject: Re: [Patch v5 04/12] irqchip: xilinx: Add support for parent intc

On 17/10/16 17:52, Zubair Lutfullah Kakakhel wrote:
> The MIPS based xilfpga platform has the following IRQ structure
> 
> Peripherals --> xilinx_intcontroller -> mips_cpu_int controller
> 
> Add support for the driver to chain the irq handler
> 
> Signed-off-by: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@...tec.com>
> 
> ---
> V4 -> V5
> Rebased to v4.9-rc1
> Missing curly braces
> 
> V3 -> V4
> Clean up if/else when a parent is found
> Pass irqchip structure to handler as data
> 
> V2 -> V3
> Reused existing parent node instead of finding again.
> Cleanup up handler based on review
> 
> V1 -> V2
> 
> No change
> ---
>  drivers/irqchip/irq-xilinx-intc.c | 26 ++++++++++++++++++++++++--
>  1 file changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-xilinx-intc.c b/drivers/irqchip/irq-xilinx-intc.c
> index 45e5154..dbf8b0c 100644
> --- a/drivers/irqchip/irq-xilinx-intc.c
> +++ b/drivers/irqchip/irq-xilinx-intc.c
> @@ -15,6 +15,7 @@
>  #include <linux/of_address.h>
>  #include <linux/io.h>
>  #include <linux/bug.h>
> +#include <linux/of_irq.h>
>  
>  /* No one else should require these constants, so define them locally here. */
>  #define ISR 0x00			/* Interrupt Status Register */
> @@ -154,11 +155,23 @@ static int xintc_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw)
>  	.map = xintc_map,
>  };
>  
> +static void xil_intc_irq_handler(struct irq_desc *desc)
> +{
> +	u32 pending;
> +
> +	do {
> +		pending = xintc_get_irq();
> +		if (pending == -1U)
> +			break;
> +		generic_handle_irq(pending);
> +	} while (true);

This is missing the chained_irq_enter()/exit() calls, which will lead to
races or lockups on the root irqchip.

> +}
> +
>  static int __init xilinx_intc_of_init(struct device_node *intc,
>  					     struct device_node *parent)
>  {
>  	u32 nr_irq;
> -	int ret;
> +	int ret, irq;
>  	struct xintc_irq_chip *irqc;
>  
>  	if (xintc_irqc) {
> @@ -221,7 +234,16 @@ static int __init xilinx_intc_of_init(struct device_node *intc,
>  		goto err_alloc;
>  	}
>  
> -	irq_set_default_host(root_domain);
> +	if (parent) {
> +		irq = irq_of_parse_and_map(intc, 0);
> +		if (irq)
> +			irq_set_chained_handler_and_data(irq,
> +							 xil_intc_irq_handler,
> +							 irqc);
> +

Shouldn't you return an error if irq is zero?

> +	} else {
> +		irq_set_default_host(root_domain);
> +	}
>  
>  	return 0;
>  
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...