Re: [BUG] "access dev->iommu_fwspec" cause crash on BPI-R2

[Joerg Roedel]

Hi Frank,

thanks for the report!

On Tue, Jan 22, 2019 at 05:09:09PM +0100, Frank Wunderlich wrote:
> Hi,
> 
> the following Patch breaks hdmi (at least) on Bananapi R2 (mt7623):
> 
> a9bf2eec5a6fc01a0a5250eaf0bf61dfd382a78a "iommu/mediatek: Use helper 
> functions to access dev->iommu_fwspec"

Does the attached diff fix the issue for you?

Thanks,

        Joerg

diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index 6ede4286b835..f60bdb85c4c0 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -442,6 +442,10 @@ static int mtk_iommu_add_device(struct device *dev)
                iommu_spec.args_count = count;
 
                mtk_iommu_create_mapping(dev, &iommu_spec);
+
+               /* dev->iommu_fwspec might have changed */
+               fwspec = dev_iommu_fwspec_get(dev);
+
                of_node_put(iommu_spec.np);
        }