On Fri, Oct 26, 2012 at 08:37:21PM +0200, Robert Jarzmik wrote:
> When using the serial console over USB to download files, and
> when the USB bandwidth is pushed to its limits, the barebox UDC
> device won't be able to absorb all the traffic.
>
> Modify the u_serial gadget so that if there is not enough room
> in buffers, don't push USB requests down the gadget driver, so
> that it is saturated, and give it a chance to NAK requests.
>
> The previous behaviour was loosing bytes (as kfifo_put is lossy).
> The fixed behavious is lossless (based on USB NAK protocol).
>
> While at it, increase a bit buffer sizes to 8kB to absorb heavy
> transfers such as a linux kernel image.
>
> Signed-off-by: Robert Jarzmik <robert.jarzmik@xxxxxxx>
Applied, thanks
Sascha
> ---
> drivers/usb/gadget/u_serial.c | 25 +++++++++++++++++--------
> 1 file changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/usb/gadget/u_serial.c b/drivers/usb/gadget/u_serial.c
> index 946b4f2..162439e 100644
> --- a/drivers/usb/gadget/u_serial.c
> +++ b/drivers/usb/gadget/u_serial.c
> @@ -74,9 +74,9 @@
> * next layer of buffering. For TX that's a circular buffer; for RX
> * consider it a NOP. A third layer is provided by the TTY code.
> */
> -#define QUEUE_SIZE 16
> +#define QUEUE_SIZE 128
> #define WRITE_BUF_SIZE 8192 /* TX only */
> -
> +#define RECV_FIFO_SIZE (1024 * 8)
> /*
> * The port structure holds info for each port, one for each minor number
> * (and thus for each /dev/ node).
> @@ -92,7 +92,7 @@ struct gs_port {
> u8 port_num;
>
> struct list_head read_pool;
> - unsigned n_read;
> + unsigned read_nb_queued;
>
> struct list_head write_pool;
>
> @@ -123,7 +123,9 @@ static unsigned gs_start_rx(struct gs_port *port)
> struct usb_ep *out = port->port_usb->out;
> unsigned started = 0;
>
> - while (!list_empty(pool)) {
> + while (!list_empty(pool) &&
> + ((out->maxpacket * (port->read_nb_queued + 1) +
> + kfifo_len(port->recv_fifo)) < RECV_FIFO_SIZE)) {
> struct usb_request *req;
> int status;
>
> @@ -134,6 +136,7 @@ static unsigned gs_start_rx(struct gs_port *port)
> /* drop lock while we call out; the controller driver
> * may need to call us back (e.g. for disconnect)
> */
> + port->read_nb_queued++;
> status = usb_ep_queue(out, req);
>
> if (status) {
> @@ -161,8 +164,9 @@ static void gs_read_complete(struct usb_ep *ep, struct usb_request *req)
> return;
>
> kfifo_put(port->recv_fifo, req->buf, req->actual);
> -
> list_add_tail(&req->list, &port->read_pool);
> + port->read_nb_queued--;
> +
> gs_start_rx(port);
> }
>
> @@ -276,7 +280,7 @@ static int gs_start_io(struct gs_port *port)
> }
>
> /* queue read requests */
> - port->n_read = 0;
> + port->read_nb_queued = 0;
> started = gs_start_rx(port);
>
> /* unblock any pending writes into our circular buffer */
> @@ -396,6 +400,7 @@ static int serial_tstc(struct console_device *cdev)
> struct gs_port *port = container_of(cdev,
> struct gs_port, cdev);
>
> + gs_start_rx(port);
> return (kfifo_len(port->recv_fifo) == 0) ? 0 : 1;
> }
>
> @@ -412,10 +417,14 @@ static int serial_getc(struct console_device *cdev)
> while (kfifo_getc(port->recv_fifo, &ch)) {
> usb_gadget_poll();
> if (is_timeout(to, 300 * MSECOND))
> - break;
> + goto timeout;
> }
>
> + gs_start_rx(port);
> return ch;
> +timeout:
> + gs_start_rx(port);
> + return -ETIMEDOUT;
> }
>
> static void serial_flush(struct console_device *cdev)
> @@ -461,7 +470,7 @@ int gserial_connect(struct gserial *gser, u8 port_num)
> */
> gser->port_line_coding = port->port_line_coding;
>
> - port->recv_fifo = kfifo_alloc(1024);
> + port->recv_fifo = kfifo_alloc(RECV_FIFO_SIZE);
>
> /*printf("gserial_connect: start ttyGS%d\n", port->port_num);*/
> gs_start_io(port);
> --
> 1.7.10
>
>
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