From: Xingang Wang <wangxingang5@xxxxxxxxxx> When request ACS in of_iommu_configure, the pci_acs_init procedure has already been called. The pci device probe procedure is like the following: pci_host_common_probe pci_device_add pci_acs_init of_iommu_configure pci_request_acs The pci_request_acs() does not work because the pci_acs_init and pci_enable_acs procedure has already finished, so the ACS is not enabled as expected. Besides, the ACS is enabled only if IOMMU is detected and the device is pci. So this fix 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when configuring IOMMU linkage"), add pci_enable_acs() and IOMMU check to make sure ACS is enabled for the pci_device. Xingang Wang (1): iommu/of: Fix request and enable ACS for of_iommu_configure drivers/iommu/of_iommu.c | 10 +++++++++- drivers/pci/pci.c | 2 +- include/linux/pci.h | 1 + 3 files changed, 11 insertions(+), 2 deletions(-) -- 2.19.1