On Wed, Apr 11, 2012 at 10:15:49AM -0300, Fabio Estevam wrote:
> On Wed, Apr 11, 2012 at 4:39 AM, Christoph Fritz
> <chf.fr...@googlemail.com> wrote:
> 
> > Can you approve this behaviour of g_ether/usbnet when using iperf?
> 
> I am not very familiar with iperf, so I will let others comment.

Hi to All,

after a while of testing and searching I can come up with a patch
that fixes g_ether <-> iperf for fsl_udc on ARM i.MX35.

The sad part is that this kind of fix is already implemented for
marvell mv_udc driver since last year but still _not_ in the ~15
other *udc.c drivers.

See here:
daec765da767e4a6a30e1298862b28f2cae9a73f
usb: gadget: mv_udc: fix dtd dma confusion

So hereby I'm CC-ing all *udc.c maintainers to point out that this
issue maybe affects you too.

And maybe someone can explain if this: 
+                               if (curr_td->next_td_ptr == 
EP_QUEUE_HEAD_NEXT_TERMINATE) {
is necessary and why (please see below).


Thanks,
 -- Christoph

---
Subject: [PATCH] usb: gadget: fsl_udc: fix dtd dma confusion

The controller will hang when doing testings with g_ether and iperf
(tool for measuring maximum TCP and UDP bandwidth).  This patch adds a
delay to wait for controller to release dtd dma before freeing it.

Signed-off-by: Christoph Fritz <chf.fr...@googlemail.com>
---
 drivers/usb/gadget/fsl_udc_core.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/drivers/usb/gadget/fsl_udc_core.c 
b/drivers/usb/gadget/fsl_udc_core.c
index 55abfb6..fc86108 100644
--- a/drivers/usb/gadget/fsl_udc_core.c
+++ b/drivers/usb/gadget/fsl_udc_core.c
@@ -1638,6 +1638,15 @@ static int process_ep_req(struct fsl_udc *udc, int pipe,
                        status = REQ_UNCOMPLETE;
                        return status;
                } else if (remaining_length) {
+                       /* wait controller release dtd dma */
+                       while ((curr_qh->curr_dtd_ptr == curr_td->td_dma)) {
+                               if (curr_td->next_td_ptr ==
+                                               EP_QUEUE_HEAD_NEXT_TERMINATE) {
+                                       udelay(100);
+                                       break;
+                               }
+                               udelay(1);
+                       }
                        if (direction) {
                                VDBG("Transmit dTD remaining length not zero");
                                status = -EPROTO;
-- 
1.7.2.5


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