[PATCH] irqchip/versatile-fpga: Handle chained IRQs properly

[PATCH] irqchip/versatile-fpga: Handle chained IRQs properly

[Sungbo Eo]

Enclose the chained handler with chained_irq_{enter,exit}(), so that the
muxed interrupts get properly acked.

This patch also fixes a reboot bug on OX820 SoC, where the jiffies timer
interrupt is never acked. The kernel waits a clock tick forever in
calibrate_delay_converge(), which leads to a boot hang.

Signed-off-by: Sungbo Eo <mans0n@gorani.run>
Cc: Neil Armstrong <narmstrong@baylibre.com>
---
 drivers/irqchip/irq-versatile-fpga.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-versatile-fpga.c b/drivers/irqchip/irq-versatile-fpga.c
index 928858dada75..08faab2fec3e 100644
--- a/drivers/irqchip/irq-versatile-fpga.c
+++ b/drivers/irqchip/irq-versatile-fpga.c
@@ -6,6 +6,7 @@
 #include <linux/irq.h>
 #include <linux/io.h>
 #include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
 #include <linux/irqchip/versatile-fpga.h>
 #include <linux/irqdomain.h>
 #include <linux/module.h>
@@ -68,12 +69,15 @@ static void fpga_irq_unmask(struct irq_data *d)
 
 static void fpga_irq_handle(struct irq_desc *desc)
 {
+	struct irq_chip *chip = irq_desc_get_chip(desc);
 	struct fpga_irq_data *f = irq_desc_get_handler_data(desc);
 	u32 status = readl(f->base + IRQ_STATUS);
 
+	chained_irq_enter(chip, desc);
+
 	if (status == 0) {
 		do_bad_IRQ(desc);
-		return;
+		goto out;
 	}
 
 	do {
@@ -82,6 +86,9 @@ static void fpga_irq_handle(struct irq_desc *desc)
 		status &= ~(1 << irq);
 		generic_handle_irq(irq_find_mapping(f->domain, irq));
 	} while (status);
+
+out:
+	chained_irq_exit(chip, desc);
 }
 
 /*
-- 
2.25.1

Re: [PATCH] irqchip/versatile-fpga: Handle chained IRQs properly

[Marc Zyngier]

Hi Sungbo,

On 2020-03-18 17:09, Sungbo Eo wrote:
> Enclose the chained handler with chained_irq_{enter,exit}(), so that 
> the
> muxed interrupts get properly acked.
> 
> This patch also fixes a reboot bug on OX820 SoC, where the jiffies 
> timer
> interrupt is never acked. The kernel waits a clock tick forever in
> calibrate_delay_converge(), which leads to a boot hang.

Nice catch.

> 
> Signed-off-by: Sungbo Eo <mans0n@gorani.run>
> Cc: Neil Armstrong <narmstrong@baylibre.com>
> ---
>  drivers/irqchip/irq-versatile-fpga.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/irqchip/irq-versatile-fpga.c
> b/drivers/irqchip/irq-versatile-fpga.c
> index 928858dada75..08faab2fec3e 100644
> --- a/drivers/irqchip/irq-versatile-fpga.c
> +++ b/drivers/irqchip/irq-versatile-fpga.c
> @@ -6,6 +6,7 @@
>  #include <linux/irq.h>
>  #include <linux/io.h>
>  #include <linux/irqchip.h>
> +#include <linux/irqchip/chained_irq.h>
>  #include <linux/irqchip/versatile-fpga.h>
>  #include <linux/irqdomain.h>
>  #include <linux/module.h>
> @@ -68,12 +69,15 @@ static void fpga_irq_unmask(struct irq_data *d)
> 
>  static void fpga_irq_handle(struct irq_desc *desc)
>  {
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
>  	struct fpga_irq_data *f = irq_desc_get_handler_data(desc);
>  	u32 status = readl(f->base + IRQ_STATUS);
> 
> +	chained_irq_enter(chip, desc);
> +

It's probably not a big deal, but I'm not fond of starting talking to
the muxing irqchip before having done the chained_irq_enter() call.

Moving that read here would probably be safer.

>  	if (status == 0) {
>  		do_bad_IRQ(desc);
> -		return;
> +		goto out;
>  	}
> 
>  	do {
> @@ -82,6 +86,9 @@ static void fpga_irq_handle(struct irq_desc *desc)
>  		status &= ~(1 << irq);
>  		generic_handle_irq(irq_find_mapping(f->domain, irq));
>  	} while (status);
> +
> +out:
> +	chained_irq_exit(chip, desc);
>  }
> 
>  /*

Otherwise looks good. If you send it again with the above fixed
and a Fixes: tag, I'll queue it.

Thanks,

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

Re: [PATCH] irqchip/versatile-fpga: Handle chained IRQs properly

[Sungbo Eo]

Hi Marc,

On 2020-03-19 02:48, Marc Zyngier wrote:
> Hi Sungbo,
> 
> On 2020-03-18 17:09, Sungbo Eo wrote:
>> Enclose the chained handler with chained_irq_{enter,exit}(), so that the
>> muxed interrupts get properly acked.
>>
>> This patch also fixes a reboot bug on OX820 SoC, where the jiffies timer
>> interrupt is never acked. The kernel waits a clock tick forever in
>> calibrate_delay_converge(), which leads to a boot hang.
> 
> Nice catch.
> 
>>
>> Signed-off-by: Sungbo Eo <mans0n@gorani.run>
>> Cc: Neil Armstrong <narmstrong@baylibre.com>
>> ---
>>  drivers/irqchip/irq-versatile-fpga.c | 9 ++++++++-
>>  1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/irqchip/irq-versatile-fpga.c
>> b/drivers/irqchip/irq-versatile-fpga.c
>> index 928858dada75..08faab2fec3e 100644
>> --- a/drivers/irqchip/irq-versatile-fpga.c
>> +++ b/drivers/irqchip/irq-versatile-fpga.c
>> @@ -6,6 +6,7 @@
>>  #include <linux/irq.h>
>>  #include <linux/io.h>
>>  #include <linux/irqchip.h>
>> +#include <linux/irqchip/chained_irq.h>
>>  #include <linux/irqchip/versatile-fpga.h>
>>  #include <linux/irqdomain.h>
>>  #include <linux/module.h>
>> @@ -68,12 +69,15 @@ static void fpga_irq_unmask(struct irq_data *d)
>>
>>  static void fpga_irq_handle(struct irq_desc *desc)
>>  {
>> +    struct irq_chip *chip = irq_desc_get_chip(desc);
>>      struct fpga_irq_data *f = irq_desc_get_handler_data(desc);
>>      u32 status = readl(f->base + IRQ_STATUS);
>>
>> +    chained_irq_enter(chip, desc);
>> +
> 
> It's probably not a big deal, but I'm not fond of starting talking to
> the muxing irqchip before having done the chained_irq_enter() call.
> 
> Moving that read here would probably be safer.

Oops, I missed it. Thanks for pointing it out.

> 
>>      if (status == 0) {
>>          do_bad_IRQ(desc);
>> -        return;
>> +        goto out;
>>      }
>>
>>      do {
>> @@ -82,6 +86,9 @@ static void fpga_irq_handle(struct irq_desc *desc)
>>          status &= ~(1 << irq);
>>          generic_handle_irq(irq_find_mapping(f->domain, irq));
>>      } while (status);
>> +
>> +out:
>> +    chained_irq_exit(chip, desc);
>>  }
>>
>>  /*
> 
> Otherwise looks good. If you send it again with the above fixed
> and a Fixes: tag, I'll queue it.

It seems the handler had been broken from the very beginning. Could you 
give me a hint on how the tag should be like?

Thanks.

> 
> Thanks,
> 
>          M.

Re: [PATCH] irqchip/versatile-fpga: Handle chained IRQs properly

[Marc Zyngier]

On 2020-03-18 18:20, Sungbo Eo wrote:
> Hi Marc,
> 
> On 2020-03-19 02:48, Marc Zyngier wrote:
>> Hi Sungbo,
>> 
>> On 2020-03-18 17:09, Sungbo Eo wrote:
>>> Enclose the chained handler with chained_irq_{enter,exit}(), so that 
>>> the
>>> muxed interrupts get properly acked.
>>> 
>>> This patch also fixes a reboot bug on OX820 SoC, where the jiffies 
>>> timer
>>> interrupt is never acked. The kernel waits a clock tick forever in
>>> calibrate_delay_converge(), which leads to a boot hang.
>> 
>> Nice catch.
>> 
>>> 
>>> Signed-off-by: Sungbo Eo <mans0n@gorani.run>
>>> Cc: Neil Armstrong <narmstrong@baylibre.com>
>>> ---
>>>  drivers/irqchip/irq-versatile-fpga.c | 9 ++++++++-
>>>  1 file changed, 8 insertions(+), 1 deletion(-)
>>> 
>>> diff --git a/drivers/irqchip/irq-versatile-fpga.c
>>> b/drivers/irqchip/irq-versatile-fpga.c
>>> index 928858dada75..08faab2fec3e 100644
>>> --- a/drivers/irqchip/irq-versatile-fpga.c
>>> +++ b/drivers/irqchip/irq-versatile-fpga.c
>>> @@ -6,6 +6,7 @@
>>>  #include <linux/irq.h>
>>>  #include <linux/io.h>
>>>  #include <linux/irqchip.h>
>>> +#include <linux/irqchip/chained_irq.h>
>>>  #include <linux/irqchip/versatile-fpga.h>
>>>  #include <linux/irqdomain.h>
>>>  #include <linux/module.h>
>>> @@ -68,12 +69,15 @@ static void fpga_irq_unmask(struct irq_data *d)
>>> 
>>>  static void fpga_irq_handle(struct irq_desc *desc)
>>>  {
>>> +    struct irq_chip *chip = irq_desc_get_chip(desc);
>>>      struct fpga_irq_data *f = irq_desc_get_handler_data(desc);
>>>      u32 status = readl(f->base + IRQ_STATUS);
>>> 
>>> +    chained_irq_enter(chip, desc);
>>> +
>> 
>> It's probably not a big deal, but I'm not fond of starting talking to
>> the muxing irqchip before having done the chained_irq_enter() call.
>> 
>> Moving that read here would probably be safer.
> 
> Oops, I missed it. Thanks for pointing it out.
> 
>> 
>>>      if (status == 0) {
>>>          do_bad_IRQ(desc);
>>> -        return;
>>> +        goto out;
>>>      }
>>> 
>>>      do {
>>> @@ -82,6 +86,9 @@ static void fpga_irq_handle(struct irq_desc *desc)
>>>          status &= ~(1 << irq);
>>>          generic_handle_irq(irq_find_mapping(f->domain, irq));
>>>      } while (status);
>>> +
>>> +out:
>>> +    chained_irq_exit(chip, desc);
>>>  }
>>> 
>>>  /*
>> 
>> Otherwise looks good. If you send it again with the above fixed
>> and a Fixes: tag, I'll queue it.
> 
> It seems the handler had been broken from the very beginning. Could
> you give me a hint on how the tag should be like?

Indeed, it has been broken forever. I'm tempted to say:

Fixes: c41b16f8c9d9d ("ARM: integrator/versatile: consolidate FPGA IRQ 
handling code")

even if it probably predates the introduction of the chained_irq_enter() 
helpers.
This will ensure this gets backported to older kernels...

Thanks,

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

[PATCH v2] irqchip/versatile-fpga: Handle chained IRQs properly

[Sungbo Eo]

Enclose the chained handler with chained_irq_{enter,exit}(), so that the
muxed interrupts get properly acked.

This patch also fixes a reboot bug on OX820 SoC, where the jiffies timer
interrupt is never acked. The kernel waits a clock tick forever in
calibrate_delay_converge(), which leads to a boot hang.

Fixes: c41b16f8c9d9 ("ARM: integrator/versatile: consolidate FPGA IRQ handling code")
Signed-off-by: Sungbo Eo <mans0n@gorani.run>
Cc: Neil Armstrong <narmstrong@baylibre.com>
---
v2: moved readl below chained_irq_enter()
    added Fixes tag

 drivers/irqchip/irq-versatile-fpga.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-versatile-fpga.c b/drivers/irqchip/irq-versatile-fpga.c
index 928858dada75..70e2cfff8175 100644
--- a/drivers/irqchip/irq-versatile-fpga.c
+++ b/drivers/irqchip/irq-versatile-fpga.c
@@ -6,6 +6,7 @@
 #include <linux/irq.h>
 #include <linux/io.h>
 #include <linux/irqchip.h>
+#include <linux/irqchip/chained_irq.h>
 #include <linux/irqchip/versatile-fpga.h>
 #include <linux/irqdomain.h>
 #include <linux/module.h>
@@ -68,12 +69,16 @@ static void fpga_irq_unmask(struct irq_data *d)
 
 static void fpga_irq_handle(struct irq_desc *desc)
 {
+	struct irq_chip *chip = irq_desc_get_chip(desc);
 	struct fpga_irq_data *f = irq_desc_get_handler_data(desc);
-	u32 status = readl(f->base + IRQ_STATUS);
+	u32 status;
+
+	chained_irq_enter(chip, desc);
 
+	status = readl(f->base + IRQ_STATUS);
 	if (status == 0) {
 		do_bad_IRQ(desc);
-		return;
+		goto out;
 	}
 
 	do {
@@ -82,6 +87,9 @@ static void fpga_irq_handle(struct irq_desc *desc)
 		status &= ~(1 << irq);
 		generic_handle_irq(irq_find_mapping(f->domain, irq));
 	} while (status);
+
+out:
+	chained_irq_exit(chip, desc);
 }
 
 /*
-- 
2.25.1

Re: [PATCH v2] irqchip/versatile-fpga: Handle chained IRQs properly

[Marc Zyngier]

On 2020-03-19 02:34, Sungbo Eo wrote:
> Enclose the chained handler with chained_irq_{enter,exit}(), so that 
> the
> muxed interrupts get properly acked.
> 
> This patch also fixes a reboot bug on OX820 SoC, where the jiffies 
> timer
> interrupt is never acked. The kernel waits a clock tick forever in
> calibrate_delay_converge(), which leads to a boot hang.
> 
> Fixes: c41b16f8c9d9 ("ARM: integrator/versatile: consolidate FPGA IRQ
> handling code")
> Signed-off-by: Sungbo Eo <mans0n@gorani.run>
> Cc: Neil Armstrong <narmstrong@baylibre.com>
> ---
> v2: moved readl below chained_irq_enter()
>     added Fixes tag
> 
>  drivers/irqchip/irq-versatile-fpga.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)

Queued for 5.7.

Thanks,

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

Re: [linux-oxnas] [PATCH v2] irqchip/versatile-fpga: Handle chained IRQs properly

[Daniel Golle]

Hi Sungbo,

I've imported your patch to openwrt master and will backport for
Linux 4.14 to also have it in the 19.07 release branch.
Thanks for your efforts and congratulations to your first upstream fix!

Once the OpenWrt buildbot[1] gets to it, we'll have snapshot images[2]
including the fix.

[1]: http://buildbot.openwrt.org/master/images/builders/oxnas%2Fox820
[2]: http://downloads.openwrt.org/snapshots/targets/oxnas/ox820/

On Thu, Mar 19, 2020 at 11:34:48AM +0900, Sungbo Eo wrote:
> Enclose the chained handler with chained_irq_{enter,exit}(), so that the
> muxed interrupts get properly acked.
> 
> This patch also fixes a reboot bug on OX820 SoC, where the jiffies timer
> interrupt is never acked. The kernel waits a clock tick forever in
> calibrate_delay_converge(), which leads to a boot hang.
> 
> Fixes: c41b16f8c9d9 ("ARM: integrator/versatile: consolidate FPGA IRQ handling code")
> Signed-off-by: Sungbo Eo <mans0n@gorani.run>
> Cc: Neil Armstrong <narmstrong@baylibre.com>
> ---
> v2: moved readl below chained_irq_enter()
>     added Fixes tag
> 
>  drivers/irqchip/irq-versatile-fpga.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-versatile-fpga.c b/drivers/irqchip/irq-versatile-fpga.c
> index 928858dada75..70e2cfff8175 100644
> --- a/drivers/irqchip/irq-versatile-fpga.c
> +++ b/drivers/irqchip/irq-versatile-fpga.c
> @@ -6,6 +6,7 @@
>  #include <linux/irq.h>
>  #include <linux/io.h>
>  #include <linux/irqchip.h>
> +#include <linux/irqchip/chained_irq.h>
>  #include <linux/irqchip/versatile-fpga.h>
>  #include <linux/irqdomain.h>
>  #include <linux/module.h>
> @@ -68,12 +69,16 @@ static void fpga_irq_unmask(struct irq_data *d)
>  
>  static void fpga_irq_handle(struct irq_desc *desc)
>  {
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
>  	struct fpga_irq_data *f = irq_desc_get_handler_data(desc);
> -	u32 status = readl(f->base + IRQ_STATUS);
> +	u32 status;
> +
> +	chained_irq_enter(chip, desc);
>  
> +	status = readl(f->base + IRQ_STATUS);
>  	if (status == 0) {
>  		do_bad_IRQ(desc);
> -		return;
> +		goto out;
>  	}
>  
>  	do {
> @@ -82,6 +87,9 @@ static void fpga_irq_handle(struct irq_desc *desc)
>  		status &= ~(1 << irq);
>  		generic_handle_irq(irq_find_mapping(f->domain, irq));
>  	} while (status);
> +
> +out:
> +	chained_irq_exit(chip, desc);
>  }
>  
>  /*
> -- 
> 2.25.1
> 
> 
> 
>