diff options
Diffstat (limited to 'drivers/net/can/usb/kvaser_usb.c')
| -rw-r--r-- | drivers/net/can/usb/kvaser_usb.c | 28 |
1 files changed, 23 insertions, 5 deletions
diff --git a/drivers/net/can/usb/kvaser_usb.c b/drivers/net/can/usb/kvaser_usb.c index d986fe83c40d..a316fa4b91ab 100644 --- a/drivers/net/can/usb/kvaser_usb.c +++ b/drivers/net/can/usb/kvaser_usb.c @@ -14,6 +14,7 @@ * Copyright (C) 2015 Valeo S.A. */ +#include <linux/kernel.h> #include <linux/completion.h> #include <linux/module.h> #include <linux/netdevice.h> @@ -584,8 +585,15 @@ static int kvaser_usb_wait_msg(const struct kvaser_usb *dev, u8 id, while (pos <= actual_len - MSG_HEADER_LEN) { tmp = buf + pos; - if (!tmp->len) - break; + /* Handle messages crossing the USB endpoint max packet + * size boundary. Check kvaser_usb_read_bulk_callback() + * for further details. + */ + if (tmp->len == 0) { + pos = round_up(pos, + dev->bulk_in->wMaxPacketSize); + continue; + } if (pos + tmp->len > actual_len) { dev_err(dev->udev->dev.parent, @@ -1316,8 +1324,19 @@ static void kvaser_usb_read_bulk_callback(struct urb *urb) while (pos <= urb->actual_length - MSG_HEADER_LEN) { msg = urb->transfer_buffer + pos; - if (!msg->len) - break; + /* The Kvaser firmware can only read and write messages that + * does not cross the USB's endpoint wMaxPacketSize boundary. + * If a follow-up command crosses such boundary, firmware puts + * a placeholder zero-length command in its place then aligns + * the real command to the next max packet size. + * + * Handle such cases or we're going to miss a significant + * number of events in case of a heavy rx load on the bus. + */ + if (msg->len == 0) { + pos = round_up(pos, dev->bulk_in->wMaxPacketSize); + continue; + } if (pos + msg->len > urb->actual_length) { dev_err(dev->udev->dev.parent, "Format error\n"); @@ -1325,7 +1344,6 @@ static void kvaser_usb_read_bulk_callback(struct urb *urb) } kvaser_usb_handle_message(dev, msg); - pos += msg->len; } |