The Tegra2 USB controller doesn't properly deal with misaligned DMA
buffers, causing corruption. This is especially prevalent with USB
network adapters, where skbuff alignment is often in the middle of a
4-byte dword.
To avoid this, allocate a temporary buffer for the DMA if the provided
buffer isn't sufficiently aligned.
Signed-off-by: Robert Morell <rmorell@xxxxxxxxxx>
---
drivers/usb/host/ehci-tegra.c | 91 +++++++++++++++++++++++++++++++++++++++++
include/linux/usb.h | 1 +
2 files changed, 92 insertions(+), 0 deletions(-)
diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c
index d990c1c..9030fa5 100644
--- a/drivers/usb/host/ehci-tegra.c
+++ b/drivers/usb/host/ehci-tegra.c
@@ -32,6 +32,8 @@
#define TEGRA_USB_USBMODE_HOST (3 << 0)
#define TEGRA_USB_PORTSC1_PTC(x) (((x) & 0xf) << 16)
+#define TEGRA_USB_DMA_ALIGN 32
+
struct tegra_ehci_context {
bool valid;
u32 command;
@@ -457,6 +459,93 @@ static int tegra_ehci_bus_resume(struct usb_hcd *hcd)
}
#endif
+struct temp_buffer {
+ void *kmalloc_ptr;
+ void *old_xfer_buffer;
+ u8 data[0];
+};
+
+static void free_temp_buffer(struct urb *urb)
+{
+ enum dma_data_direction dir;
+ struct temp_buffer *temp;
+
+ if (!(urb->transfer_flags & URB_ALIGNED_TEMP_BUFFER))
+ return;
+
+ dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+
+ temp = container_of(urb->transfer_buffer, struct temp_buffer,
+ data);
+
+ if (dir == DMA_FROM_DEVICE)
+ memcpy(temp->old_xfer_buffer, temp->data,
+ urb->transfer_buffer_length);
+ urb->transfer_buffer = temp->old_xfer_buffer;
+ kfree(temp->kmalloc_ptr);
+
+ urb->transfer_flags &= ~URB_ALIGNED_TEMP_BUFFER;
+}
+
+static int alloc_temp_buffer(struct urb *urb, gfp_t mem_flags)
+{
+ enum dma_data_direction dir;
+ struct temp_buffer *temp, *kmalloc_ptr;
+ size_t kmalloc_size;
+ void *data;
+
+ if (urb->num_sgs || urb->sg ||
+ urb->transfer_buffer_length == 0 ||
+ !((uintptr_t)urb->transfer_buffer & (TEGRA_USB_DMA_ALIGN - 1)))
+ return 0;
+
+ dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE;
+
+ /* Allocate a buffer with enough padding for alignment */
+ kmalloc_size = urb->transfer_buffer_length +
+ sizeof(struct temp_buffer) + TEGRA_USB_DMA_ALIGN - 1;
+
+ kmalloc_ptr = kmalloc(kmalloc_size, mem_flags);
+ if (!kmalloc_ptr)
+ return -ENOMEM;
+
+ /* Position our struct temp_buffer such that data is aligned */
+ temp = PTR_ALIGN(kmalloc_ptr + 1, TEGRA_USB_DMA_ALIGN) - 1;
+
+ temp->kmalloc_ptr = kmalloc_ptr;
+ temp->old_xfer_buffer = urb->transfer_buffer;
+ if (dir == DMA_TO_DEVICE)
+ memcpy(temp->data, urb->transfer_buffer,
+ urb->transfer_buffer_length);
+ urb->transfer_buffer = temp->data;
+
+ urb->transfer_flags |= URB_ALIGNED_TEMP_BUFFER;
+
+ return 0;
+}
+
+static int tegra_ehci_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb,
+ gfp_t mem_flags)
+{
+ int ret;
+
+ ret = alloc_temp_buffer(urb, mem_flags);
+ if (ret)
+ return ret;
+
+ ret = usb_hcd_map_urb_for_dma(hcd, urb, mem_flags);
+ if (ret)
+ free_temp_buffer(urb);
+
+ return ret;
+}
+
+static void tegra_ehci_unmap_urb_for_dma(struct usb_hcd *hcd, struct urb *urb)
+{
+ usb_hcd_unmap_urb_for_dma(hcd, urb);
+ free_temp_buffer(urb);
+}
+
static const struct hc_driver tegra_ehci_hc_driver = {
.description = hcd_name,
.product_desc = "Tegra EHCI Host Controller",
@@ -472,6 +561,8 @@ static const struct hc_driver tegra_ehci_hc_driver = {
.shutdown = tegra_ehci_shutdown,
.urb_enqueue = ehci_urb_enqueue,
.urb_dequeue = ehci_urb_dequeue,
+ .map_urb_for_dma = tegra_ehci_map_urb_for_dma,
+ .unmap_urb_for_dma = tegra_ehci_unmap_urb_for_dma,
.endpoint_disable = ehci_endpoint_disable,
.endpoint_reset = ehci_endpoint_reset,
.get_frame_number = ehci_get_frame,
diff --git a/include/linux/usb.h b/include/linux/usb.h
index 35fe6ab..6d4566e 100644
--- a/include/linux/usb.h
+++ b/include/linux/usb.h
@@ -975,6 +975,7 @@ extern int usb_disabled(void);
#define URB_SETUP_MAP_SINGLE 0x00100000 /* Setup packet DMA mapped */
#define URB_SETUP_MAP_LOCAL 0x00200000 /* HCD-local setup packet */
#define URB_DMA_SG_COMBINED 0x00400000 /* S-G entries were combined */
+#define URB_ALIGNED_TEMP_BUFFER 0x00800000 /* Temp buffer was alloc'd */
struct usb_iso_packet_descriptor {
unsigned int offset;
--
1.7.2.2
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