From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benoit Goby Subject: [PATCH v3 4/4] USB: ehci: tegra: Align DMA transfers to 32 bytes Date: Thu, 17 Feb 2011 14:15:04 -0800 Message-ID: <1297980904-23466-5-git-send-email-benoit@android.com> References: <1297980904-23466-1-git-send-email-benoit@android.com> Return-path: In-Reply-To: <1297980904-23466-1-git-send-email-benoit-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org> Sender: linux-usb-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: David Brownell , Greg Kroah-Hartman , linux-usb-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: Benoit Goby , Olof Johansson , Erik Gilling , linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Robert Morell List-Id: linux-tegra@vger.kernel.org From: Robert Morell 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 Signed-off-by: Benoit Goby --- drivers/usb/host/ehci-tegra.c | 90 +++++++++++++++++++++++++++++++++++++++++ 1 files changed, 90 insertions(+), 0 deletions(-) diff --git a/drivers/usb/host/ehci-tegra.c b/drivers/usb/host/ehci-tegra.c index 5c5ee91..c64d629 100644 --- a/drivers/usb/host/ehci-tegra.c +++ b/drivers/usb/host/ehci-tegra.c @@ -28,6 +28,8 @@ #define TEGRA_USB_PORTSC1_PTC(x) (((x) & 0xf) << 16) +#define TEGRA_USB_DMA_ALIGN 32 + struct tegra_ehci_hcd { struct ehci_hcd *ehci; struct tegra_usb_phy *phy; @@ -388,6 +390,92 @@ 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", @@ -403,6 +491,8 @@ 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, -- 1.7.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html