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From:   Christoph Hellwig <hch@lst.de>
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     Alex Williamson <alex.williamson@redhat.com>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Christian Benvenuti <benve@cisco.com>,
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        Will Deacon <will@kernel.org>, Christoph Hellwig <hch@lst.de>,
        "Tian, Kevin" <kevin.tian@intel.com>
Subject: Re: [PATCH 1/5] iommu: Replace uses of IOMMU_CAP_CACHE_COHERENCY
 with dev_is_dma_coherent()
Message-ID: <20220406053039.GA10580@lst.de>
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On Tue, Apr 05, 2022 at 01:16:00PM -0300, Jason Gunthorpe wrote:
> diff --git a/drivers/infiniband/hw/usnic/usnic_uiom.c b/drivers/infiniband/hw/usnic/usnic_uiom.c
> index 760b254ba42d6b..24d118198ac756 100644
> --- a/drivers/infiniband/hw/usnic/usnic_uiom.c
> +++ b/drivers/infiniband/hw/usnic/usnic_uiom.c
> @@ -42,6 +42,7 @@
>  #include <linux/list.h>
>  #include <linux/pci.h>
>  #include <rdma/ib_verbs.h>
> +#include <linux/dma-map-ops.h>
>  
>  #include "usnic_log.h"
>  #include "usnic_uiom.h"
> @@ -474,6 +475,12 @@ int usnic_uiom_attach_dev_to_pd(struct usnic_uiom_pd *pd, struct device *dev)
>  	struct usnic_uiom_dev *uiom_dev;
>  	int err;
>  
> +	if (!dev_is_dma_coherent(dev)) {

Which part of the comment at the top of dma-map-ops.h is not clear
enough to you?