On LoPAR "DMA Window Manipulation Calls", it's recommended to remove the default DMA window for the device, before attempting to configure a DDW, in order to make the maximum resources available for the next DDW to be created.
This is a requirement for some devices to use DDW, given they only allow one DMA window. If setting up a new DDW fails anywhere after the removal of this default DMA window, restore it using reset_dma_window. Signed-off-by: Leonardo Bras <leobra...@gmail.com> --- arch/powerpc/platforms/pseries/iommu.c | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index de633f6ae093..68d1ea957ac7 100644 --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c @@ -1074,8 +1074,9 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn) u64 dma_addr, max_addr; struct device_node *dn; u32 ddw_avail[3]; + struct direct_window *window; - struct property *win64; + struct property *win64, *dfl_win; struct dynamic_dma_window_prop *ddwprop; struct failed_ddw_pdn *fpdn; @@ -1110,8 +1111,19 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn) if (ret) goto out_failed; - /* - * Query if there is a second window of size to map the + /* + * First step of setting up DDW is removing the default DMA window, + * if it's present. It will make all the resources available to the + * new DDW window. + * If anything fails after this, we need to restore it. + */ + + dfl_win = of_find_property(pdn, "ibm,dma-window", NULL); + if (dfl_win) + remove_dma_window(pdn, ddw_avail, dfl_win); + + /* + * Query if there is a window of size to map the * whole partition. Query returns number of windows, largest * block assigned to PE (partition endpoint), and two bitmasks * of page sizes: supported and supported for migrate-dma. @@ -1219,6 +1231,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn) kfree(win64); out_failed: + if (dfl_win) + reset_dma_window(dev, pdn); fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL); if (!fpdn) -- 2.25.4