Re: [PATCH] Alchemy: modernize Pb1200 IRQ cascade handling code.

[Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>]

Hello.

Manuel Lauss wrote:

> Signed-off-by: Manuel Lauss <mano@xxxxxxxxxxxxxxxxxxxxxxx>
>   
[...]
> diff --git a/arch/mips/au1000/pb1200/irqmap.c b/arch/mips/au1000/pb1200/irqmap.c
> index 2a505ad..7229f30 100644
> --- a/arch/mips/au1000/pb1200/irqmap.c
> +++ b/arch/mips/au1000/pb1200/irqmap.c
> @@ -48,62 +48,26 @@ int __initdata au1xxx_nr_irqs = ARRAY_SIZE(au1xxx_irq_map);
>  /*
>   * Support for External interrupts on the Pb1200 Development platform.
>   */
> -static volatile int pb1200_cascade_en;
>  
> -irqreturn_t pb1200_cascade_handler(int irq, void *dev_id)
> +static void pb1200_cascade_handler(unsigned int irq, struct irq_desc *desc)
>  {
>  	unsigned short bisr = bcsr->int_status;
> -	int extirq_nr = 0;
> -
> -	/* Clear all the edge interrupts. This has no effect on level. */
>   

  Note this comment...

> -	bcsr->int_status = bisr;
> -	for ( ; bisr; bisr &= bisr - 1) {
> -		extirq_nr = PB1200_INT_BEGIN + __ffs(bisr);
> -		/* Ack and dispatch IRQ */
> -		do_IRQ(extirq_nr);
> -	}
>  
> -	return IRQ_RETVAL(1);
> +	for ( ; bisr; bisr &= bisr - 1)
> +		generic_handle_irq(PB1200_INT_BEGIN + __ffs(bisr));
>  }
>  
> -inline void pb1200_enable_irq(unsigned int irq_nr)
> +static void pb1200_unmask_irq(unsigned int irq_nr)
>  {
>  	bcsr->intset_mask = 1 << (irq_nr - PB1200_INT_BEGIN);
>  	bcsr->intset = 1 << (irq_nr - PB1200_INT_BEGIN);
>  }
>  
> -inline void pb1200_disable_irq(unsigned int irq_nr)
> +static void pb1200_maskack_irq(unsigned int irq_nr)
>  {
>  	bcsr->intclr_mask = 1 << (irq_nr - PB1200_INT_BEGIN);
>  	bcsr->intclr = 1 << (irq_nr - PB1200_INT_BEGIN);
>   

  I wonder what's the difference between int{clr|set} and 
int{clr|set}_mask registers...

[...]
> +	bcsr->int_status = 1 << (irq_nr - PB1200_INT_BEGIN);	/* ack */
>   

  The above comment said that writing to this register has no effect on 
the level-triggered interrupts, so this statement doesn't seem to make 
sense since you're treating all interrupts as level-triggered below.

> @@ -113,12 +77,9 @@ static struct irq_chip external_irq_type = {
>  #ifdef CONFIG_MIPS_DB1200
>  	.name = "Db1200 Ext",
>  #endif
> -	.startup  = pb1200_startup_irq,
> -	.shutdown = pb1200_shutdown_irq,
> -	.ack      = pb1200_disable_irq,
> -	.mask     = pb1200_disable_irq,
> -	.mask_ack = pb1200_disable_irq,
> -	.unmask   = pb1200_enable_irq,
> +	.mask		= pb1200_maskack_irq,
> +	.mask_ack	= pb1200_maskack_irq,
>   

  You can use the same function for the mask() and mask_ack() methods 
but it only should be masking IRQ, as clearing it doesn't make sense...

> @@ -147,14 +108,14 @@ void _board_init_irq(void)
>  	}
>  #endif
>  
> -	for (irq = PB1200_INT_BEGIN; irq <= PB1200_INT_END; irq++) {
> -		set_irq_chip_and_handler(irq, &external_irq_type,
> -					 handle_level_irq);
> -		pb1200_disable_irq(irq);
> -	}
> +	/* mask & disable & ack all */
> +	bcsr->intclr_mask = 0xffff;
> +	bcsr->intclr = 0xffff;
> +	bcsr->int_status = 0xffff;
> +
> +	for (irq = PB1200_INT_BEGIN; irq <= PB1200_INT_END; irq++)
> +		set_irq_chip_and_handler_name(irq, &external_irq_type,
> +					 handle_level_irq, "level");
>   

  Are all those IRQs indeed level-triggered?

WBR, Sergei