[PATCH] iommu/arm-smmu-v3: suppress MSI allocation failure message

[PATCH] iommu/arm-smmu-v3: suppress MSI allocation failure message

[Nate Watterson]

From: Sinan Kaya <okaya@codeaurora.org>

Even though QDF2400 supports MSI interrupts with SMMUv3, it is not enabled
in ACPI FW to preserve compatibility with older kernel versions. Code is
emitting warning message during boot.

This is causing some test tools to record a false warning and is causing
support issues.

Better reduce the message level.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Nate Watterson <nwatters@codeaurora.org>
---
 drivers/iommu/arm-smmu-v3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 744592d..2118fda 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -2331,7 +2331,7 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
 	/* Allocate MSIs for evtq, gerror and priq. Ignore cmdq */
 	ret = platform_msi_domain_alloc_irqs(dev, nvec, arm_smmu_write_msi_msg);
 	if (ret) {
-		dev_warn(dev, "failed to allocate MSIs\n");
+		dev_info(dev, "failed to allocate MSIs\n");
 		return;
 	}
 
-- 
Qualcomm Datacenter Technologies, Inc. on behalf of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux
Foundation Collaborative Project.

[PATCH] iommu/arm-smmu-v3: suppress MSI allocation failure message

[Robin Murphy]

[ +Marc just in case ]

On 17/01/18 18:39, Nate Watterson wrote:
> From: Sinan Kaya <okaya@codeaurora.org>
> 
> Even though QDF2400 supports MSI interrupts with SMMUv3, it is not enabled
> in ACPI FW to preserve compatibility with older kernel versions. Code is
> emitting warning message during boot.
> 
> This is causing some test tools to record a false warning and is causing
> support issues.
> 
> Better reduce the message level.

Ugh, that's unfortunate, since there are also plenty of genuine error 
conditions encapsulated in there which we *would* want to report as such 
(but still then fall back to wired IRQs if possible). Is the return 
value sufficient to differentiate the "there is no MSI parent" and 
"there are MSIs but something went wrong" cases, or is it more 
complicated than that?

Robin.

> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
> Signed-off-by: Nate Watterson <nwatters@codeaurora.org>
> ---
>   drivers/iommu/arm-smmu-v3.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index 744592d..2118fda 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -2331,7 +2331,7 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
>   	/* Allocate MSIs for evtq, gerror and priq. Ignore cmdq */
>   	ret = platform_msi_domain_alloc_irqs(dev, nvec, arm_smmu_write_msi_msg);
>   	if (ret) {
> -		dev_warn(dev, "failed to allocate MSIs\n");
> +		dev_info(dev, "failed to allocate MSIs\n");
>   		return;
>   	}
>   
> 

[PATCH] iommu/arm-smmu-v3: suppress MSI allocation failure message

[Marc Zyngier]

On 17/01/18 18:54, Robin Murphy wrote:
> [ +Marc just in case ]
> 
> On 17/01/18 18:39, Nate Watterson wrote:
>> From: Sinan Kaya <okaya@codeaurora.org>
>>
>> Even though QDF2400 supports MSI interrupts with SMMUv3, it is not enabled
>> in ACPI FW to preserve compatibility with older kernel versions. Code is
>> emitting warning message during boot.
>>
>> This is causing some test tools to record a false warning and is causing
>> support issues.
>>
>> Better reduce the message level.
> 
> Ugh, that's unfortunate, since there are also plenty of genuine error 
> conditions encapsulated in there which we *would* want to report as such 
> (but still then fall back to wired IRQs if possible). Is the return 
> value sufficient to differentiate the "there is no MSI parent" and 
> "there are MSIs but something went wrong" cases, or is it more 
> complicated than that?

Indeed. How about checking dev->msi_domain first, which should tell you
whether it is even possible to allocate MSIs, and fallback to wired IRQs
instead. That way, we keep the warning on genuine failures to allocate
MSIs, and you get to add a nice "Falling back to wired interrupts"
message when msi_domain is NULL.

Thoughts?

	M.

> 
> Robin.
> 
>> Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
>> Signed-off-by: Nate Watterson <nwatters@codeaurora.org>
>> ---
>>   drivers/iommu/arm-smmu-v3.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index 744592d..2118fda 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -2331,7 +2331,7 @@ static void arm_smmu_setup_msis(struct arm_smmu_device *smmu)
>>   	/* Allocate MSIs for evtq, gerror and priq. Ignore cmdq */
>>   	ret = platform_msi_domain_alloc_irqs(dev, nvec, arm_smmu_write_msi_msg);
>>   	if (ret) {
>> -		dev_warn(dev, "failed to allocate MSIs\n");
>> +		dev_info(dev, "failed to allocate MSIs\n");
>>   		return;
>>   	}
>>   
>>


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

[PATCH] iommu/arm-smmu-v3: suppress MSI allocation failure message

[Joerg Roedel]

On Wed, Jan 17, 2018 at 07:08:39PM +0000, Marc Zyngier wrote:
> On 17/01/18 18:54, Robin Murphy wrote:

> Indeed. How about checking dev->msi_domain first, which should tell you
> whether it is even possible to allocate MSIs, and fallback to wired IRQs
> instead. That way, we keep the warning on genuine failures to allocate
> MSIs, and you get to add a nice "Falling back to wired interrupts"
> message when msi_domain is NULL.
> 
> Thoughts?

That sounds much better then the proposed patch. I am not really interested
in changing log-levels to make test-tools happy.


	Joerg