From: Badhri Jagan Sridharan <[email protected]> For dual speed gadget, with current no. of request(10), there is possibility of corner case occurrence where all 10 requests are queued to HW without setting IOC bit, which could lead to data stall in RNDIS tethering and RNDIS local networking.
With this patch, counter will be incremented before queueing request to HW and sets IOC bit for every nth request due to which the corner case of all requests queued to HW without IOC bit set will be avoided. Cc: Felipe Balbi <[email protected]> Cc: Greg Kroah-Hartman <[email protected]> Cc: Mike Looijmans <[email protected]> Cc: Robert Baldyga <[email protected]> Cc: Android Kernel Team <[email protected]> Cc: John Stultz <[email protected]> Cc: Sumit Semwal <[email protected]> Signed-off-by: Vijayavardhan Vennapusa <[email protected]> [pundir: cherry-picked this patch from AOSP experimental/android-4.4 tree.] Signed-off-by: Amit Pundir <[email protected]> --- Cherry-picked this patch from AOSP common/experimental/android-4.4 tree. I could not find upstream submission history for this patch, so my apologies in advance if this has already been NACKed before. drivers/usb/gadget/function/u_ether.c | 25 +++++++++++++++---------- 1 file changed, 15 insertions(+), 10 deletions(-) diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c index 9a69332..7f98a2d 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -64,7 +64,7 @@ struct eth_dev { spinlock_t req_lock; /* guard {rx,tx}_reqs */ struct list_head tx_reqs, rx_reqs; - atomic_t tx_qlen; + unsigned tx_qlen; struct sk_buff_head rx_frames; @@ -464,7 +464,6 @@ static void tx_complete(struct usb_ep *ep, struct usb_request *req) spin_unlock(&dev->req_lock); dev_kfree_skb_any(skb); - atomic_dec(&dev->tx_qlen); if (netif_carrier_ok(dev->net)) netif_wake_queue(dev->net); } @@ -584,12 +583,19 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb, req->length = length; - /* throttle high/super speed IRQ rate back slightly */ - if (gadget_is_dualspeed(dev->gadget)) - req->no_interrupt = (dev->gadget->speed == USB_SPEED_HIGH || - dev->gadget->speed == USB_SPEED_SUPER) - ? ((atomic_read(&dev->tx_qlen) % dev->qmult) != 0) - : 0; + /* throttle highspeed IRQ rate back slightly */ + if (gadget_is_dualspeed(dev->gadget) && + (dev->gadget->speed == USB_SPEED_HIGH)) { + dev->tx_qlen++; + if (dev->tx_qlen == qmult) { + req->no_interrupt = 0; + dev->tx_qlen = 0; + } else { + req->no_interrupt = 1; + } + } else { + req->no_interrupt = 0; + } retval = usb_ep_queue(in, req, GFP_ATOMIC); switch (retval) { @@ -598,7 +604,6 @@ static netdev_tx_t eth_start_xmit(struct sk_buff *skb, break; case 0: net->trans_start = jiffies; - atomic_inc(&dev->tx_qlen); } if (retval) { @@ -625,7 +630,7 @@ static void eth_start(struct eth_dev *dev, gfp_t gfp_flags) rx_fill(dev, gfp_flags); /* and open the tx floodgates */ - atomic_set(&dev->tx_qlen, 0); + dev->tx_qlen = 0; netif_wake_queue(dev->net); } -- 1.9.1
