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SubjectRe: [RFC/PATCH 2/2] usb: ffs/dwc3: pad epout buffer size when not aligned to maxpacketsize
Hi,

On Mon, Oct 28, 2013 at 06:13:00PM -0700, David Cohen wrote:
> DWC3 requires buffer size to be aligned to maxpacketsize of an out
> endpoint. ffs_epfile_io() needs to pad epout buffer to match above
> condition if DWC3 controller is used.
>
> This patch solves an specific situation but a more generic solution
> should be found.
>
> Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
> ---
> drivers/usb/gadget/f_fs.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
> index 75e4b78..33880e6 100644
> --- a/drivers/usb/gadget/f_fs.c
> +++ b/drivers/usb/gadget/f_fs.c
> @@ -27,6 +27,7 @@
> #include <linux/usb/composite.h>
> #include <linux/usb/functionfs.h>
>
> +#include "gadget_chips.h"
>
> #define FUNCTIONFS_MAGIC 0xa647361 /* Chosen by a honest dice roll ;) */
>
> @@ -755,10 +756,12 @@ static ssize_t ffs_epfile_io(struct file *file,
> char __user *buf, size_t len, int read)
> {
> struct ffs_epfile *epfile = file->private_data;
> + struct usb_gadget *gadget = epfile->ffs->gadget;
> struct ffs_ep *ep;
> char *data = NULL;
> ssize_t ret;
> int halt;
> + size_t orig_len = len;
>
> goto first_try;
> do {
> @@ -794,6 +797,22 @@ first_try:
> goto error;
> }
>
> + /*
> + * DWC3 requires buffer size to be aligned to maxpacketsize
> + * of an out endpoint.
> + * FIXME: a more generic solution might be necessary.
> + */

see, gadget drivers shouldn't have to know about DWC3 at all. They need
to know that current UDC has a quirk where EP OUT transactions need to
be aligned to wMaxPacketSize, so what I was expecting to see here was:

if (test_bit(USB_GADGET_QUIRK_EP_OUT_ALIGNED_SIZE, &gadget->qirks) &&
!IS_ALIGNED(len, ep->ep->desc->wMaxPacketSize))
len = align_length(orig_len, wMaxPacketSize);


--
balbi
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