On Wed, Mar 20, 2013 at 11:26:49PM +0100, Michael Grzeschik wrote:
> Each TD can maintain five buffer pointers. Each of them is 4k aligned.
> There is no need to limit this to less then possible. This patch lowers
> the overhead of extra TDs.
>
> Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
> ---
> drivers/usb/chipidea/udc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> index 70296c7..007a97a 100644
> --- a/drivers/usb/chipidea/udc.c
> +++ b/drivers/usb/chipidea/udc.c
> @@ -693,8 +693,8 @@ static int _ep_queue(struct usb_ep *ep, struct usb_request *req,
> goto done;
> }
>
> - if (req->length > 4 * CI13XXX_PAGE_SIZE) {
> - req->length = 4 * CI13XXX_PAGE_SIZE;
> + if (req->length > 5 * CI13XXX_PAGE_SIZE) {
> + req->length = 5 * CI13XXX_PAGE_SIZE;
> retval = -EMSGSIZE;
> dev_warn(mEp->ci->dev, "request length truncated\n");
> }
> --
> 1.8.2.rc2
>From the discussion with Peter, this patch is wrong. We have to
keep that limit to 4 in the special case when (req->dma % PAGE_COUNT).
Michael
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