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
