Hi Sergei, Sergei Shtylyov wrote: > Hello. > > Holger brunck wrote: > >> From: Stefan Bigler <stefan.bigler@xxxxxxxxxxx> > >> Some usb serial host drivers expect a short packet before they forward >> the data to the application. This is caused by them trying to read more >> than one packet at a time. So when the gadget sends an exact multiple >> of the maximum packet size, it should append a zero-length packet. >> The gadget driver for fsl_qe was not handling this case correctly. >> This patch adds sending of a null packet if it is the last packet of >> a frame and the request length is USB_EP0_MAX_SIZE (64 Byte). > >> See also commit 2e25134122c25ebb0679b4bbd536fb46c669f9d7 > > Linus has asked to also specify the commit summary in parens. > Ok I will do this if the patch is with regards to its content ok. >> Signed-off-by: Stefan Bigler <stefan.bigler@xxxxxxxxxxx> >> Signed-off-by: Holger Brunck <holger.brunck@xxxxxxxxxxx> >> Cc: Li Yang <leoli@xxxxxxxxxxxxx> >> Cc: David Brownell <dbrownell@xxxxxxxxxxxxxxxxxxxxx> > >> --- >> drivers/usb/gadget/fsl_qe_udc.c | 3 +++ >> 1 files changed, 3 insertions(+), 0 deletions(-) >> >> diff --git a/drivers/usb/gadget/fsl_qe_udc.c >> b/drivers/usb/gadget/fsl_qe_udc.c >> index 7881f12..279454a 100644 >> --- a/drivers/usb/gadget/fsl_qe_udc.c >> +++ b/drivers/usb/gadget/fsl_qe_udc.c >> @@ -1229,6 +1229,9 @@ static int frame_create_tx(struct qe_ep *ep, >> struct qe_frame *frame) >> else >> reval = sendnulldata(ep, frame, 0); > > No, really you shouldn't send null data in every case when > req->req.length - ep->sent <= 0, only if req->req.length == 0 or > req->req.zero == 1... > Hm, yes this piece of code looks a bit odd to me too. And I did not understand what it should solve. But I let it untouched, because the bug my patch should fix is in my eyes a different topic. >> + if (req->req.zero && (req->req.length == USB_EP0_MAX_SIZE)) > > Not (req->req.length % USB_EP0_MAX_SIZE == 0)? Also, you should > probably check that ep->sent == req->req.length here... > No not (req->req.length % USB_EP0_MAX_SIZE == 0), because the nulldata which is missing should only be send if it is the last packet of a frame and not every time a 64byte packet is send. Best regards Holger -- 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
