From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:6f8:1178:4:290:27ff:fe1d:cc33]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TSjqt-0000x4-1Z for barebox@lists.infradead.org; Mon, 29 Oct 2012 07:33:40 +0000 Date: Mon, 29 Oct 2012 08:33:30 +0100 From: Sascha Hauer Message-ID: <20121029073330.GH1641@pengutronix.de> References: <1351276641-24913-1-git-send-email-robert.jarzmik@free.fr> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1351276641-24913-1-git-send-email-robert.jarzmik@free.fr> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: barebox-bounces@lists.infradead.org Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH] usb: add flow control to u_serial To: Robert Jarzmik Cc: barebox@lists.infradead.org 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 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 > > > _______________________________________________ > barebox mailing list > barebox@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/barebox > -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox