Hi,
2011/12/3 Simon Glass <s...@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 <s...@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
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