Hello!
On 12/29/2016 11:45 PM, Nikita Yushchenko wrote:
It is possible that PCI device supports 64-bit DMA addressing, and thus
it's driver sets device's dma_mask to DMA_BIT_MASK(64), however PCI host
Its.
bridge has limitations on inbound transactions addressing. Example of
such setup is NVME
Isn't it called NVMe?
SSD device connected to RCAR PCIe controller.
R=Car.
Previously there was attempt to handle this via bus notifier: after
driver is attached to PCI device, bridge driver gets notifier callback,
and resets dma_mask from there. However, this is racy: PCI device driver
could already allocate buffers and/or start i/o in probe routine.
In NVME case, i/o is started in workqueue context, and this race gives
"sometimes works, sometimes not" effect.
Proper solution should make driver's dma_set_mask() call to fail if host
bridge can't support mask being set.
This patch makes __swiotlb_dma_supported() to check mask being set for
"To" not needed here.
PCI device against dma_mask of struct device corresponding to PCI host
bridge (one with name "pciXXXX:YY"), if that dma_mask is set.
This is the least destructive approach: currently dma_mask of that device
object is not used anyhow, thus all existing setups will work as before,
and modification is required only in actually affected components -
driver of particular PCI host bridge, and dma_map_ops of particular
platform.
Signed-off-by: Nikita Yushchenko <nikita.yoush@xxxxxxxxxxxxxxxxxx>
---
arch/arm64/mm/dma-mapping.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c
index 290a84f..49645277 100644
--- a/arch/arm64/mm/dma-mapping.c
+++ b/arch/arm64/mm/dma-mapping.c
[...]
@@ -347,6 +348,16 @@ static int __swiotlb_get_sgtable(struct device *dev, struct sg_table *sgt,
static int __swiotlb_dma_supported(struct device *hwdev, u64 mask)
{
+#ifdef CONFIG_PCI
+ if (dev_is_pci(hwdev)) {
+ struct pci_dev *pdev = to_pci_dev(hwdev);
+ struct pci_host_bridge *br = pci_find_host_bridge(pdev->bus);
+
+ if (br->dev.dma_mask && (*br->dev.dma_mask) &&
+ (mask & (*br->dev.dma_mask)) != mask)
Hum, inner parens not necessary?
[...]
MBR, Sergei
