linux-kernel - Re: [PATCH] irqchip: xilinx: Enable generic irq multi handler

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Date:   Fri, 4 Mar 2022 07:58:17 +0100
From:   Michal Simek <michal.simek@...inx.com>
To:     Robert Hancock <robert.hancock@...ian.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "michal.simek@...inx.com" <michal.simek@...inx.com>,
        "git@...inx.com" <git@...inx.com>,
        "monstr@...str.eu" <monstr@...str.eu>
CC:     "maz@...nel.org" <maz@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "stefan.asserhall@...inx.com" <stefan.asserhall@...inx.com>
Subject: Re: [PATCH] irqchip: xilinx: Enable generic irq multi handler



On 3/3/22 18:01, Robert Hancock wrote:
> On Thu, 2022-03-03 at 17:11 +0100, Michal Simek wrote:
>> Register default arch handler via driver instead of directly pointing to
>> xilinx intc controller. This patch makes architecture code more generic.
>>
>> Signed-off-by: Michal Simek <michal.simek@...inx.com>
>> Reviewed-by: Stefan Asserhall <stefan.asserhall@...inx.com>
>> ---
>>
>>   arch/microblaze/Kconfig           |  2 ++
>>   arch/microblaze/include/asm/irq.h |  3 ---
>>   arch/microblaze/kernel/irq.c      | 16 +---------------
>>   drivers/irqchip/irq-xilinx-intc.c | 22 +++++++++++++++++++++-
>>   4 files changed, 24 insertions(+), 19 deletions(-)
>>
>> diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
>> index 59798e43cdb0..da568e981604 100644
>> --- a/arch/microblaze/Kconfig
>> +++ b/arch/microblaze/Kconfig
>> @@ -45,6 +45,8 @@ config MICROBLAZE
>>   	select SET_FS
>>   	select ZONE_DMA
>>   	select TRACE_IRQFLAGS_SUPPORT
>> +	select GENERIC_IRQ_MULTI_HANDLER
>> +	select HANDLE_DOMAIN_IRQ
>>   
>>   # Endianness selection
>>   choice
>> diff --git a/arch/microblaze/include/asm/irq.h
>> b/arch/microblaze/include/asm/irq.h
>> index 0a28e80bbab0..cb6ab55d1d01 100644
>> --- a/arch/microblaze/include/asm/irq.h
>> +++ b/arch/microblaze/include/asm/irq.h
>> @@ -11,7 +11,4 @@
>>   struct pt_regs;
>>   extern void do_IRQ(struct pt_regs *regs);
>>   
>> -/* should be defined in each interrupt controller driver */
>> -extern unsigned int xintc_get_irq(void);
>> -
>>   #endif /* _ASM_MICROBLAZE_IRQ_H */
>> diff --git a/arch/microblaze/kernel/irq.c b/arch/microblaze/kernel/irq.c
>> index 903dad822fad..1f8cb4c4f74f 100644
>> --- a/arch/microblaze/kernel/irq.c
>> +++ b/arch/microblaze/kernel/irq.c
>> @@ -20,27 +20,13 @@
>>   #include <linux/irqchip.h>
>>   #include <linux/of_irq.h>
>>   
>> -static u32 concurrent_irq;
>> -
>>   void __irq_entry do_IRQ(struct pt_regs *regs)
>>   {
>> -	unsigned int irq;
>>   	struct pt_regs *old_regs = set_irq_regs(regs);
>>   	trace_hardirqs_off();
>>   
>>   	irq_enter();
>> -	irq = xintc_get_irq();
>> -next_irq:
>> -	BUG_ON(!irq);
>> -	generic_handle_irq(irq);
>> -
>> -	irq = xintc_get_irq();
>> -	if (irq != -1U) {
>> -		pr_debug("next irq: %d\n", irq);
>> -		++concurrent_irq;
>> -		goto next_irq;
>> -	}
>> -
>> +	handle_arch_irq(regs);
>>   	irq_exit();
>>   	set_irq_regs(old_regs);
>>   	trace_hardirqs_on();
>> diff --git a/drivers/irqchip/irq-xilinx-intc.c b/drivers/irqchip/irq-xilinx-
>> intc.c
>> index 356a59755d63..c6710190c152 100644
>> --- a/drivers/irqchip/irq-xilinx-intc.c
>> +++ b/drivers/irqchip/irq-xilinx-intc.c
>> @@ -110,7 +110,7 @@ static struct irq_chip intc_dev = {
>>   	.irq_mask_ack = intc_mask_ack,
>>   };
>>   
>> -unsigned int xintc_get_irq(void)
>> +static unsigned int xintc_get_irq(void)
>>   {
>>   	unsigned int irq = -1;
>>   	u32 hwirq;
>> @@ -164,6 +164,25 @@ static void xil_intc_irq_handler(struct irq_desc *desc)
>>   	chained_irq_exit(chip, desc);
>>   }
>>   
>> +static u32 concurrent_irq;
> 
> Not sure what this variable is for? It seems to be incremented, but never read.

I used this when I was checking how irqs are working and how many concurrent_irq 
I am getting. It was read via debugger not via any linux interface.

Thanks,
Michal