On Fri, 2021-06-04 at 15:46 +0800, Kai Ye wrote: > Add print information necessary if user not enable sva. [] > diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c [] > @@ -387,15 +387,22 @@ static void uacce_release(struct device *dev) > > > static unsigned int uacce_enable_sva(struct device *parent, unsigned int flags) > { > + int ret; [] > + ret = iommu_dev_enable_feature(parent, IOMMU_DEV_FEAT_IOPF); > + if (ret) { > + dev_err(parent, "failed to enable IOPF feature! ret = %d\n", ret); Perhaps use %pe, ERR_PTR(ret) to get descriptive error output > + dev_err(parent, "failed to enable SVA feature! ret = %d\n", ret); here too