Hi,
2011/12/3 Simon Glass sjg@chromium.org:
CONFIG_USB_EHCI_DATA_ALIGN sets the required alignment of data for USB packets (e.g. 4 means word-aligned). This is required for Tegra to operate.
Signed-off-by: Simon Glass sjg@chromium.org
Changes in v2:
- Tidy code style in USB buffer alignment code
- Display prominent warning when alignment code is triggered
README | 6 ++++++ drivers/usb/host/ehci-hcd.c | 29 +++++++++++++++++++++++++++++ 2 files changed, 35 insertions(+), 0 deletions(-)
diff --git a/README b/README index fda0190..3194846 100644 --- a/README +++ b/README @@ -1096,6 +1096,12 @@ The following options need to be configured: May be defined to allow interrupt polling instead of using asynchronous interrupts
- CONFIG_USB_EHCI_DATA_ALIGN sets the required alignment of
- data for USB packets (e.g. 4 means word-aligned). This is
- required for Tegra to operate. Since we want all callers to
- align data for us, we display a warning when the alignment
- code is triggered.
- USB Device: Define the below if you wish to use the USB console. Once firmware is rebuilt from a serial console issue the diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c index 2197119..23458b6 100644 --- a/drivers/usb/host/ehci-hcd.c +++ b/drivers/usb/host/ehci-hcd.c @@ -322,6 +322,24 @@ ehci_submit_async(struct usb_device *dev, unsigned long pipe, void *buffer, int timeout; int ret = 0;
+#ifdef CONFIG_USB_EHCI_DATA_ALIGN
- /* In case ehci host requires alignment for buffers */
- void *align_buf = NULL;
- void *orig_buf = buffer;
- int unaligned = (int)buffer & (CONFIG_USB_EHCI_DATA_ALIGN - 1);
- if (unaligned) {
- printf("EHCI: Unaligned buffer: performance will suffer\n");
- align_buf = malloc(length + CONFIG_USB_EHCI_DATA_ALIGN);
- if (!align_buf)
- return -1;
- buffer = (void *)(((ulong)align_buf +
- CONFIG_USB_EHCI_DATA_ALIGN - 1) &
- ~(CONFIG_USB_EHCI_DATA_ALIGN - 1));
- if (usb_pipeout(pipe))
- memcpy(buffer, orig_buf, length);
- }
I do not really like this solution. Maybe we can introduce something like an usbbuf_alloc() function that takes care of the alignment. This saves the memcpy() for every transmit. I know it has more impact if we do it like that, but I think it is cleaner.
Kind regards,
Remy