[PATCH 03/10] usb: musb: gadget: fix bulk IN infinit hangs in double buffer case

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Ming Lei <tom.leiming@xxxxxxxxx>

This patch fixes one infinite hang of bulk IN transfer in double buffer
case, the hang can be observed easily by test #6 of usbtest if musb is
configured as g_zero and fifo mode 3 is taken to enable double fifo.

In fact, the patch only removes the check for non-empty fifo before
loading data from new request into fifo since the check is not correct:

	-in double buffer case, fifo may accommodate more than one packet,
	even though it has contained one packet already and is non-empty

	-since last DMA is completed before calling musb_g_tx, it is sure
	that fifo may accommodate at least one packet

Without applying the patch, new requst enqueued from .complte may not
have a chance to be loaded into fifo, then will never be completed and
cause infinite hangs.

With the patch, on my beagle B5, test#6(queued bulk in) can be passed and
test result may go beyond 33Mbyte/s if musb is configured as g_zero and
fifo mode 3 is taken, follows the test command:

	#testusb -D DEV_NAME -c 1024 -t 6 -s 32768 -g 8   [1]

[1],
    -source of testusb : tools/usb/testusb.c under linux kernel;

Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
Acked-by: Anand Gadiyar <gadiyar@xxxxxx>
Cc: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx>
Cc: Anand Gadiyar <gadiyar@xxxxxx>
Cc: Mike Frysinger <vapier@xxxxxxxxxx>
Cc: Sergei Shtylyov <sshtylyov@xxxxxxxxxxxxx>
Signed-off-by: Felipe Balbi <balbi@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 drivers/usb/musb/musb_gadget.c |   12 ------------
 1 files changed, 0 insertions(+), 12 deletions(-)

diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index de0ca90..f206c94 100644
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -504,18 +504,6 @@ void musb_g_tx(struct musb *musb, u8 epnum)
 			/* ... or if not, then complete it. */
 			musb_g_giveback(musb_ep, request, 0);
 
-			/*
-			 * Kickstart next transfer if appropriate;
-			 * the packet that just completed might not
-			 * be transmitted for hours or days.
-			 * REVISIT for double buffering...
-			 * FIXME revisit for stalls too...
-			 */
-			musb_ep_select(mbase, epnum);
-			csr = musb_readw(epio, MUSB_TXCSR);
-			if (csr & MUSB_TXCSR_FIFONOTEMPTY)
-				return;
-
 			request = musb_ep->desc ? next_request(musb_ep) : NULL;
 			if (!request) {
 				DBG(4, "%s idle now\n",
-- 
1.7.2

--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [Linux Media]     [Linux Input]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [Old Linux USB Devel Archive]

  Powered by Linux