On Mon, Nov 07, 2022 at 04:14:32PM -0800, Nicolin Chen wrote:

On Mon, Nov 07, 2022 at 03:26:45PM +0000, Will Deacon wrote:

quoted

quoted

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index ba47c73f5b8c..01fd7df16cb9 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -2430,23 +2430,14 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
                      goto out_unlock;
              }
      } else if (smmu_domain->smmu != smmu) {
-             dev_err(dev,
-                     "cannot attach to SMMU %s (upstream of %s)\n",
-                     dev_name(smmu_domain->smmu->dev),
-                     dev_name(smmu->dev));
-             ret = -ENXIO;
+             ret = -EINVAL;
              goto out_unlock;
      } else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
                 master->ssid_bits != smmu_domain->s1_cfg.s1cdmax) {
-             dev_err(dev,
-                     "cannot attach to incompatible domain (%u SSID bits != %u)\n",
-                     smmu_domain->s1_cfg.s1cdmax, master->ssid_bits);
              ret = -EINVAL;
              goto out_unlock;
      } else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
                 smmu_domain->stall_enabled != master->stall_enabled) {
-             dev_err(dev, "cannot attach to stall-%s domain\n",
-                     smmu_domain->stall_enabled ? "enabled" : "disabled");
              ret = -EINVAL;
              goto out_unlock;
      }

quoted

I think it would be helpful to preserve these messages using
dev_err_ratelimited() so that attach failure can be diagnosed without
having to hack the messages back into the driver.

Thank you for the review.

The change is already picked up last week. Yet, I can add prints
back with a followup patch, if no one has a problem with that.

Sorry, I fell behind with upstream so I got to this late. A patch on top
would be fantastic!

Also, I am not quite sure what the use case would be to have an
error print. Perhaps dev_dbg() would be more fitting if it is
just for diagnosis?

Sure, that works for me. I think the messages are useful for folks
triggering this path e.g. via sysfs but if they're limited to debug I think
that's better than removing them altogether.

Cheers,

Will

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