On Fri, Jan 28, 2011 at 6:23 PM, Marek Szyprowski
<m.szyprowski@xxxxxxxxxxx> wrote:
> Some UDC drivers fails to queue a request if req->buf == NULL even for
> ZLP requests. This patch add support for dummy request buffer in case of
> ZLP request.
>
> Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> ---
> Âdrivers/usb/gadget/f_fs.c | Â Â5 +++++
> Â1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/usb/gadget/f_fs.c b/drivers/usb/gadget/f_fs.c
> index 1499f9e..f0a0907 100644
> --- a/drivers/usb/gadget/f_fs.c
> +++ b/drivers/usb/gadget/f_fs.c
> @@ -356,6 +356,7 @@ static void ffs_ep0_complete(struct usb_ep *ep, struct usb_request *req)
> Â Â Â Âcomplete_all(&ffs->ep0req_completion);
> Â}
>
> +static char ffs_tmp_buf[1];
> Âstatic int __ffs_ep0_queue_wait(struct ffs_data *ffs, char *data, size_t len)
> Â{
> Â Â Â Âstruct usb_request *req = ffs->ep0req;
> @@ -368,6 +369,10 @@ static int __ffs_ep0_queue_wait(struct ffs_data *ffs, char *data, size_t len)
>    Âreq->buf   Â= data;
>    Âreq->length  = len;
>
> + Â Â Â /* UDC layer require to provide a buffer even for ZLP */
> + Â Â Â if (req->buf == NULL)
> + Â Â Â Â Â Â Â req->buf = ffs_tmp_buf;
For ZLP the buffer is not supposed to be touched.
A driver may not accept req with NULL buf, but it _must_ not use the buf.
So, we'd better poison the buf so that we can catch buggy code.
Something like :-
> + if (req->buf == NULL)
> + req->buf = 0xdeadbabe;
--
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