[PATCH] drm/amd/display: add a WARN() to irq service functions

[PATCH] drm/amd/display: add a WARN() to irq service functions

[Hamza Mahfooz]

Currently, if we encounter unimplemented functions, it is difficult to
tell what caused them just by looking at dmesg and that is compounded by
the fact that it is often hard to reproduce said issues. So, to have
access to more detailed debugging information, add a WARN() to
dal_irq_service_ack() and dal_irq_service_set() that only triggers when
we encounter an unimplemented function.

Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
---
 drivers/gpu/drm/amd/display/dc/irq/irq_service.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/dc/irq/irq_service.c b/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
index 7bad39bba86b..b895bdd8dc55 100644
--- a/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
+++ b/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
@@ -112,8 +112,11 @@ bool dal_irq_service_set(
 
 	dal_irq_service_ack(irq_service, source);
 
-	if (info->funcs && info->funcs->set)
+	if (info->funcs && info->funcs->set) {
+		WARN(info->funcs->set == dal_irq_service_dummy_set,
+		     "%s: src: %d, st: %d\n", __func__, source, enable);
 		return info->funcs->set(irq_service, info, enable);
+	}
 
 	dal_irq_service_set_generic(irq_service, info, enable);
 
@@ -146,8 +149,11 @@ bool dal_irq_service_ack(
 		return false;
 	}
 
-	if (info->funcs && info->funcs->ack)
+	if (info->funcs && info->funcs->ack) {
+		WARN(info->funcs->ack == dal_irq_service_dummy_ack,
+		     "%s: src: %d\n", __func__, source);
 		return info->funcs->ack(irq_service, info);
+	}
 
 	dal_irq_service_ack_generic(irq_service, info);
 
-- 
2.38.0

Re: [PATCH] drm/amd/display: add a WARN() to irq service functions

[Rodrigo Siqueira]

Hi Hamza,

On 10/14/22 11:31, Hamza Mahfooz wrote:
> Currently, if we encounter unimplemented functions, it is difficult to
> tell what caused them just by looking at dmesg and that is compounded by
> the fact that it is often hard to reproduce said issues. So, to have
> access to more detailed debugging information, add a WARN() to
> dal_irq_service_ack() and dal_irq_service_set() that only triggers when
> we encounter an unimplemented function.

Do you know the specific issue that triggered this unimplemented 
function? It might be useful to describe the situation in the commit 
message where you see this problem.

> 
> Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
> ---
>   drivers/gpu/drm/amd/display/dc/irq/irq_service.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/irq/irq_service.c b/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
> index 7bad39bba86b..b895bdd8dc55 100644
> --- a/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
> +++ b/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
> @@ -112,8 +112,11 @@ bool dal_irq_service_set(
>   
>   	dal_irq_service_ack(irq_service, source);
>   
> -	if (info->funcs && info->funcs->set)
> +	if (info->funcs && info->funcs->set) {
> +		WARN(info->funcs->set == dal_irq_service_dummy_set,
> +		     "%s: src: %d, st: %d\n", __func__, source, enable);
>   		return info->funcs->set(irq_service, info, enable);

Do you know if we may hit this condition multiple times?

> +	}
>   
>   	dal_irq_service_set_generic(irq_service, info, enable);
>   
> @@ -146,8 +149,11 @@ bool dal_irq_service_ack(
>   		return false;
>   	}
>   
> -	if (info->funcs && info->funcs->ack)
> +	if (info->funcs && info->funcs->ack) {
> +		WARN(info->funcs->ack == dal_irq_service_dummy_ack,
> +		     "%s: src: %d\n", __func__, source);
>   		return info->funcs->ack(irq_service, info);
> +	}
>   
>   	dal_irq_service_ack_generic(irq_service, info);
>   

Just for curiosity, did you run some IGT tests?

Thanks
Siqueira

Re: [PATCH] drm/amd/display: add a WARN() to irq service functions

[Hamza Mahfooz]

On 2022-10-17 09:06, Rodrigo Siqueira wrote:
> Hi Hamza,
> 
> On 10/14/22 11:31, Hamza Mahfooz wrote:
>> Currently, if we encounter unimplemented functions, it is difficult to
>> tell what caused them just by looking at dmesg and that is compounded by
>> the fact that it is often hard to reproduce said issues. So, to have
>> access to more detailed debugging information, add a WARN() to
>> dal_irq_service_ack() and dal_irq_service_set() that only triggers when
>> we encounter an unimplemented function.
> 
> Do you know the specific issue that triggered this unimplemented 
> function? It might be useful to describe the situation in the commit 
> message where you see this problem.
> 

Ya, I'll do that in v2.

>>
>> Signed-off-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
>> ---
>>   drivers/gpu/drm/amd/display/dc/irq/irq_service.c | 10 ++++++++--
>>   1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/display/dc/irq/irq_service.c 
>> b/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
>> index 7bad39bba86b..b895bdd8dc55 100644
>> --- a/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
>> +++ b/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
>> @@ -112,8 +112,11 @@ bool dal_irq_service_set(
>>       dal_irq_service_ack(irq_service, source);
>> -    if (info->funcs && info->funcs->set)
>> +    if (info->funcs && info->funcs->set) {
>> +        WARN(info->funcs->set == dal_irq_service_dummy_set,
>> +             "%s: src: %d, st: %d\n", __func__, source, enable);
>>           return info->funcs->set(irq_service, info, enable);
> 
> Do you know if we may hit this condition multiple times?

Yes, it is possible that it will be hit multiple times from different 
callers.

> 
>> +    }
>>       dal_irq_service_set_generic(irq_service, info, enable);
>> @@ -146,8 +149,11 @@ bool dal_irq_service_ack(
>>           return false;
>>       }
>> -    if (info->funcs && info->funcs->ack)
>> +    if (info->funcs && info->funcs->ack) {
>> +        WARN(info->funcs->ack == dal_irq_service_dummy_ack,
>> +             "%s: src: %d\n", __func__, source);
>>           return info->funcs->ack(irq_service, info);
>> +    }
>>       dal_irq_service_ack_generic(irq_service, info);
> 
> Just for curiosity, did you run some IGT tests?

No, this was encountered during manual testing.

> 
> Thanks
> Siqueira
> 

-- 
Hamza