In pch_pic_parse_madt(), a NULL parent pointer will be
returned from acpi_get_vec_parent() for second pch-pic domain
related to second bridge while calling eiointc_acpi_init() at
first time, where the parent of it has not been initialized
yet, and will be initialized during second time calling
eiointc_acpi_init(). So, it's reasonable to return zero so
that failure of acpi_table_parse_madt() will be avoided, or else
acpi_cascade_irqdomain_init() will return and initialization of
followed pch_msi domain will be skipped.

Although it does not matter when pch_msi_parse_madt() returns
-EINVAL if no invalid parent is found, it's also reasonable to
return zero for that.

Change-Id: I4d278534999ec3e5c8db6d40155ba2665d9de86f
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
---
 drivers/irqchip/irq-loongson-eiointc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
index d15fd38c1756..62a632d73991 100644
--- a/drivers/irqchip/irq-loongson-eiointc.c
+++ b/drivers/irqchip/irq-loongson-eiointc.c
@@ -343,7 +343,7 @@ static int __init pch_pic_parse_madt(union acpi_subtable_headers *header,
 	if (parent)
 		return pch_pic_acpi_init(parent, pchpic_entry);
 
-	return -EINVAL;
+	return 0;
 }
 
 static int __init pch_msi_parse_madt(union acpi_subtable_headers *header,
@@ -355,7 +355,7 @@ static int __init pch_msi_parse_madt(union acpi_subtable_headers *header,
 	if (parent)
 		return pch_msi_acpi_init(parent, pchmsi_entry);
 
-	return -EINVAL;
+	return 0;
 }
 
 static int __init acpi_cascade_irqdomain_init(void)
-- 
2.31.1

On Fri, 24 Mar 2023 06:08:50 +0000,
Jianmin Lv <lvjianmin@loongson.cn> wrote:
> 
> In pch_pic_parse_madt(), a NULL parent pointer will be
> returned from acpi_get_vec_parent() for second pch-pic domain
> related to second bridge while calling eiointc_acpi_init() at
> first time, where the parent of it has not been initialized
> yet, and will be initialized during second time calling
> eiointc_acpi_init(). So, it's reasonable to return zero so
> that failure of acpi_table_parse_madt() will be avoided, or else
> acpi_cascade_irqdomain_init() will return and initialization of
> followed pch_msi domain will be skipped.
> 
> Although it does not matter when pch_msi_parse_madt() returns
> -EINVAL if no invalid parent is found, it's also reasonable to
> return zero for that.
> 
> Change-Id: I4d278534999ec3e5c8db6d40155ba2665d9de86f
> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
> ---
>  drivers/irqchip/irq-loongson-eiointc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
> index d15fd38c1756..62a632d73991 100644
> --- a/drivers/irqchip/irq-loongson-eiointc.c
> +++ b/drivers/irqchip/irq-loongson-eiointc.c
> @@ -343,7 +343,7 @@ static int __init pch_pic_parse_madt(union acpi_subtable_headers *header,
>  	if (parent)
>  		return pch_pic_acpi_init(parent, pchpic_entry);
>  
> -	return -EINVAL;
> +	return 0;

Why can't you detect this particular case instead of blindly
suppressing the error?

	M.

-- 
Without deviation from the norm, progress is not possible.

On 2023/3/24 下午11:36, Marc Zyngier wrote:
> On Fri, 24 Mar 2023 06:08:50 +0000,
> Jianmin Lv <lvjianmin@loongson.cn> wrote:
>>
>> In pch_pic_parse_madt(), a NULL parent pointer will be
>> returned from acpi_get_vec_parent() for second pch-pic domain
>> related to second bridge while calling eiointc_acpi_init() at
>> first time, where the parent of it has not been initialized
>> yet, and will be initialized during second time calling
>> eiointc_acpi_init(). So, it's reasonable to return zero so
>> that failure of acpi_table_parse_madt() will be avoided, or else
>> acpi_cascade_irqdomain_init() will return and initialization of
>> followed pch_msi domain will be skipped.
>>
>> Although it does not matter when pch_msi_parse_madt() returns
>> -EINVAL if no invalid parent is found, it's also reasonable to
>> return zero for that.
>>
>> Change-Id: I4d278534999ec3e5c8db6d40155ba2665d9de86f
>> Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
>> ---
>>   drivers/irqchip/irq-loongson-eiointc.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
>> index d15fd38c1756..62a632d73991 100644
>> --- a/drivers/irqchip/irq-loongson-eiointc.c
>> +++ b/drivers/irqchip/irq-loongson-eiointc.c
>> @@ -343,7 +343,7 @@ static int __init pch_pic_parse_madt(union acpi_subtable_headers *header,
>>   	if (parent)
>>   		return pch_pic_acpi_init(parent, pchpic_entry);
>>   
>> -	return -EINVAL;
>> +	return 0;
> 
> Why can't you detect this particular case instead of blindly
> suppressing the error?
> 

For dual-bridges scenario, parent handle for pch_pic IRQ domain will be 
set by acpi_set_vec_parent() during each eiointc initialization. And
the parent handle for one pch_pic will be set during *first* eiointc
entry parsing, and the parent handle for another pch_pic will be
set during *second* eiointc entry parsing. But two pch_pic entries
will be parsed during each eiointc entry parsing, so a NULL parent
pointer must be returned druing first eiointc initialization, which
is reasonable and should not be treated as an error.

The calling stack of pch_pic_parse_madt (where acpi_get_vec_parent is 
called to get parent handle) is like this:

cpuintc_acpi_init
   acpi_cascade_irqdomain_init(in cpuintc driver)
     acpi_table_parse_madt
       eiointc_parse_madt
         eiointc_acpi_init /* this will be called two times 
corresponding  to parsing two eiointc entries in MADT under dual-bridges 
scenario*/
           acpi_set_vec_parent /* set parent handle for one pch_pic 
during first eiointc entry parsing, and set parent handle for another 
pch_pic during second eiointc entry parsing*/
             acpi_cascade_irqdomain_init(in eiointc driver)
               acpi_table_parse_madt
                 pch_pic_parse_madt /* this will be called twice because 
of two pchpic entries, and only one valid parent handle will be returned 
from acpi_get_vec_parent() during first eiointc entry parsing (another 
parent handle is not set yet), so a NULL parent pointer must be returned 
during first eiointc entry parsing, which is reasonable and should not 
be treated as an error.*/

Thanks!

> 	M.
>