Re: [PATCH] iommu: silence iommu group prints

[Robin Murphy <robin.murphy@arm.com>]

On 27/02/2020 11:57 am, Russell King wrote:
> On the LX2160A, there are lots (about 160) of IOMMU messages produced
> during boot; this is excessive.  Reduce the severity of these messages
> to debug level.

That's... a lot. Does the system really have that many devices, or is 
some driver being stupid and repeatedly populating and destroying an 
entire bus in a probe-deferral dance?

I have no real objection to the change itself - it can be handy to see 
these when diagnosing dmesg dumps over email, but it's nothing that 
can't be gleaned from sysfs later even without dynamic debug - I'm just 
curious as to what leads to such an unusually obnoxious spamming.

Robin.

> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
> ---
>   drivers/iommu/iommu.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 3ead597e1c57..304281ec623b 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -741,7 +741,7 @@ int iommu_group_add_device(struct iommu_group *group, struct device *dev)
>   
>   	trace_add_device_to_group(group->id, dev);
>   
> -	dev_info(dev, "Adding to iommu group %d\n", group->id);
> +	dev_dbg(dev, "Adding to iommu group %d\n", group->id);
>   
>   	return 0;
>   
> @@ -775,7 +775,7 @@ void iommu_group_remove_device(struct device *dev)
>   	struct iommu_group *group = dev->iommu_group;
>   	struct group_device *tmp_device, *device = NULL;
>   
> -	dev_info(dev, "Removing from iommu group %d\n", group->id);
> +	dev_dbg(dev, "Removing from iommu group %d\n", group->id);
>   
>   	/* Pre-notify listeners that a device is being removed. */
>   	blocking_notifier_call_chain(&group->notifier,
> 
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