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USB: ehci: tegra: Align DMA transfers to 32 bytes

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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@nvidia.com>
This commit is contained in:
Robert Morell
2011-01-26 19:06:49 -08:00
committed by Benoit Goby
parent a0d7774b25
commit da0fbc7f9b
1 changed files with 90 additions and 0 deletions
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90
drivers/usb/host/ehci-tegra.c
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@@ -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;
@@ -468,6 +470,92 @@ 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;
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",
@@ -483,6 +571,8 @@ 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,