Subject: Re: [PATCH v3] ARM: footbridge: replace setup_irq() by request_irq()

From: Russell King - ARM Linux admin <[email-masked]>
Date: Thu, 12 Mar 2020 12:34:32 +0000

On Sun, Mar 01, 2020 at 05:51:31PM +0530, afzal mohammed wrote:
> request_irq() is preferred over setup_irq(). Invocations of setup_irq()
> occur after memory allocators are ready.
> 
> Per tglx[1], setup_irq() existed in olden days when allocators were not
> ready by the time early interrupts were initialized.
> 
> Hence replace setup_irq() by request_irq().
> 
> [1] https://lkml.kernel.org/r/alpine.DEB.2.20.1710191609480.1971@nanos
> 
> Signed-off-by: afzal mohammed <[email-masked]>
> ---
> Hi sub-arch maintainers,
> 
> If the patch is okay, please take it thr' your tree.

This patch causes a build warning:

arch/arm/mach-footbridge/isa-irq.c:113:15: warning: unused variable 'irq' [-Wunused-variable]

because you introduce a new 'int irq' variable in a sub-block where the
parent already declares 'irq', causing the parent 'irq' to be unused.

Hence, I'm dropping this patch.

I think you need to look more carefully at the code you are modifying,
and maybe even build test it.  Cross compilers are available from
kernel.org.

Russell.

> 
> Regards
> afzal
> 
> v3:
>  * Split out from series, also create subarch level patch as Thomas
> 	suggested to take it thr' respective maintainers
>  * Modify string displayed in case of error as suggested by Thomas
>  * Re-arrange code as required to improve readability
>  * Remove irrelevant parts from commit message & improve
>  
> v2:
>  * Replace pr_err("request_irq() on %s failed" by
>            pr_err("%s: request_irq() failed"
>  * Commit message massage
> 
>  arch/arm/mach-footbridge/dc21285-timer.c | 11 +++--------
>  arch/arm/mach-footbridge/isa-irq.c       | 10 ++++------
>  arch/arm/mach-footbridge/isa-timer.c     | 11 +++--------
>  3 files changed, 10 insertions(+), 22 deletions(-)
> 
> diff --git a/arch/arm/mach-footbridge/dc21285-timer.c b/arch/arm/mach-footbridge/dc21285-timer.c
> index f76212d2dbf1..2908c9ef3c9b 100644
> --- a/arch/arm/mach-footbridge/dc21285-timer.c
> +++ b/arch/arm/mach-footbridge/dc21285-timer.c
> @@ -101,13 +101,6 @@ static irqreturn_t timer1_interrupt(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> -static struct irqaction footbridge_timer_irq = {
> -	.name		= "dc21285_timer1",
> -	.handler	= timer1_interrupt,
> -	.flags		= IRQF_TIMER | IRQF_IRQPOLL,
> -	.dev_id		= &ckevt_dc21285,
> -};
> -
>  /*
>   * Set up timer interrupt.
>   */
> @@ -118,7 +111,9 @@ void __init footbridge_timer_init(void)
>  
>  	clocksource_register_hz(&cksrc_dc21285, rate);
>  
> -	setup_irq(ce->irq, &footbridge_timer_irq);
> +	if (request_irq(ce->irq, timer1_interrupt, IRQF_TIMER | IRQF_IRQPOLL,
> +			"dc21285_timer1", &ckevt_dc21285))
> +		pr_err("Failed to request irq %d (dc21285_timer1)", ce->irq);
>  
>  	ce->cpumask = cpumask_of(smp_processor_id());
>  	clockevents_config_and_register(ce, rate, 0x4, 0xffffff);
> diff --git a/arch/arm/mach-footbridge/isa-irq.c b/arch/arm/mach-footbridge/isa-irq.c
> index 88a553932c33..16c5455199e8 100644
> --- a/arch/arm/mach-footbridge/isa-irq.c
> +++ b/arch/arm/mach-footbridge/isa-irq.c
> @@ -96,11 +96,6 @@ static void isa_irq_handler(struct irq_desc *desc)
>  	generic_handle_irq(isa_irq);
>  }
>  
> -static struct irqaction irq_cascade = {
> -	.handler = no_action,
> -	.name = "cascade",
> -};
> -
>  static struct resource pic1_resource = {
>  	.name	= "pic1",
>  	.start	= 0x20,
> @@ -146,6 +141,8 @@ void __init isa_init_irq(unsigned int host_irq)
>  	}
>  
>  	if (host_irq != (unsigned int)-1) {
> +		int irq = IRQ_ISA_CASCADE;
> +
>  		for (irq = _ISA_IRQ(0); irq < _ISA_IRQ(8); irq++) {
>  			irq_set_chip_and_handler(irq, &isa_lo_chip,
>  						 handle_level_irq);
> @@ -160,7 +157,8 @@ void __init isa_init_irq(unsigned int host_irq)
>  
>  		request_resource(&ioport_resource, &pic1_resource);
>  		request_resource(&ioport_resource, &pic2_resource);
> -		setup_irq(IRQ_ISA_CASCADE, &irq_cascade);
> +		if (request_irq(irq, no_action, 0, "cascade", NULL))
> +			pr_err("Failed to request irq %d (cascade)\n", irq);
>  
>  		irq_set_chained_handler(host_irq, isa_irq_handler);
>  
> diff --git a/arch/arm/mach-footbridge/isa-timer.c b/arch/arm/mach-footbridge/isa-timer.c
> index 82f45591fb2c..723e3eae995d 100644
> --- a/arch/arm/mach-footbridge/isa-timer.c
> +++ b/arch/arm/mach-footbridge/isa-timer.c
> @@ -25,17 +25,12 @@ static irqreturn_t pit_timer_interrupt(int irq, void *dev_id)
>  	return IRQ_HANDLED;
>  }
>  
> -static struct irqaction pit_timer_irq = {
> -	.name		= "pit",
> -	.handler	= pit_timer_interrupt,
> -	.flags		= IRQF_TIMER | IRQF_IRQPOLL,
> -	.dev_id		= &i8253_clockevent,
> -};
> -
>  void __init isa_timer_init(void)
>  {
>  	clocksource_i8253_init();
>  
> -	setup_irq(i8253_clockevent.irq, &pit_timer_irq);
> +	if (request_irq(i8253_clockevent.irq, pit_timer_interrupt,
> +			IRQF_TIMER | IRQF_IRQPOLL, "pit", &i8253_clockevent))
> +		pr_err("Failed to request irq %d(pit)\n", i8253_clockevent.irq);
>  	clockevent_i8253_init(false);
>  }
> -- 
> 2.25.1
> 
> 
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