From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932820AbcGHOGJ (ORCPT ); Fri, 8 Jul 2016 10:06:09 -0400 Received: from mail-wm0-f43.google.com ([74.125.82.43]:35173 "EHLO mail-wm0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932737AbcGHOF5 convert rfc822-to-8bit (ORCPT ); Fri, 8 Jul 2016 10:05:57 -0400 From: Michal Nazarewicz To: Felipe Balbi , Baolin Wang , Felipe Ferreri Tonello Cc: Greg KH , eu@felipetonello.com, dan.carpenter@oracle.com, USB , LKML , Mark Brown Subject: Re: [PATCH] usb: gadget: f_midi: Add checking if it need align buffer's size to an ep's maxpacketsize In-Reply-To: <87inwgi7nh.fsf@linux.intel.com> Organization: http://mina86.com/ References: <8ff4f814afc70cf9c00cc6718d7ae93fae94884a.1467881565.git.baolin.wang@linaro.org> <87inwgi7nh.fsf@linux.intel.com> User-Agent: Notmuch/0.19+53~g2e63a09 (http://notmuchmail.org) Emacs/25.1.50.1 (x86_64-unknown-linux-gnu) Face: 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 X-Face: -TR8(rDTHy/(xl?SfWd1|3:TTgDIatE^t'vop%*gVg[kn$t{EpK(P"VQ=~T2#ysNmJKN$"yTRLB4YQs$4{[.]Fc1)*O]3+XO^oXM>Q#b^ix,O)Zbn)q[y06$`e3?C)`CwR9y5riE=fv^X@x$y?D:XO6L&x4f-}}I4=VRNwiA^t1-ZrVK^07.Pi/57c_du'& X-PGP: 50751FF4 X-PGP-FP: AC1F 5F5C D418 88F8 CC84 5858 2060 4012 5075 1FF4 X-Hashcash: 1:20:160708:eu@felipetonello.com::thT7kiqgG2jvkTVt:000000000000000000000000000000000000000000lSh X-Hashcash: 1:20:160708:baolin.wang@linaro.org::Uxts4s55Z1d3iaJ4:0000000000000000000000000000000000000000dds X-Hashcash: 1:20:160708:balbi@kernel.org::4zUZ7IZROqmp7wr4:02Ged X-Hashcash: 1:20:160708:eu@felipetonello.com::K2JAp8psZ1mOk5V0:000000000000000000000000000000000000000002Zgj X-Hashcash: 1:20:160708:linux-kernel@vger.kernel.org::B/VJ8wxHlzXVtaZX:0000000000000000000000000000000002dfK X-Hashcash: 1:20:160708:gregkh@linuxfoundation.org::uAQmvEHtHMN+Jytt:0000000000000000000000000000000000025Xk X-Hashcash: 1:20:160708:dan.carpenter@oracle.com::z/PBdLUR6dPGYEXn:00000000000000000000000000000000000007QFs X-Hashcash: 1:20:160708:linux-usb@vger.kernel.org::YtJb2n6XQrGkfy0f:0000000000000000000000000000000000004zsV X-Hashcash: 1:20:160708:broonie@kernel.org::WctzYHj+GObvaIWu:00000000000000000000000000000000000000000005igm Date: Fri, 08 Jul 2016 16:05:53 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 08 2016, Felipe Balbi wrote: > My take on this is that it's calling max_t() to try and align to > wMaxPacketSize. We can see from original commit what was the intent: > > commit 03d27ade4941076b34c823d63d91dc895731a595 > Author: Felipe F. Tonello > Date: Wed Mar 9 19:39:30 2016 +0000 > > usb: gadget: f_midi: Fixed a bug when buflen was smaller than wMaxPacketSize > > buflen by default (256) is smaller than wMaxPacketSize (512) in high-speed > devices. > > That caused the OUT endpoint to freeze if the host send any data packet of > length greater than 256 bytes. > > This is an example dump of what happended on that enpoint: > HOST: [DATA][Length=260][...] > DEVICE: [NAK] > HOST: [PING] > DEVICE: [NAK] > HOST: [PING] > DEVICE: [NAK] > ... > HOST: [PING] > DEVICE: [NAK] > > This patch fixes this problem by setting the minimum usb_request's buffer size > for the OUT endpoint as its wMaxPacketSize. > > Acked-by: Michal Nazarewicz > Signed-off-by: Felipe F. Tonello > Signed-off-by: Felipe Balbi > > diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c > index 56e2dde99b03..9ad51dcab982 100644 > --- a/drivers/usb/gadget/function/f_midi.c > +++ b/drivers/usb/gadget/function/f_midi.c > @@ -360,7 +360,9 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt) > /* allocate a bunch of read buffers and queue them all at once. */ > for (i = 0; i < midi->qlen && err == 0; i++) { > struct usb_request *req = > - midi_alloc_ep_req(midi->out_ep, midi->buflen); > + midi_alloc_ep_req(midi->out_ep, > + max_t(unsigned, midi->buflen, > + bulk_out_desc.wMaxPacketSize)); > if (req == NULL) > return -ENOMEM; > > Seems to me usb_ep_align_maybe() would cover this case just as well. But > then, Felipe's UDC driver seems to need quirk_ep_out_aligned_size. Felipe? In that case, I agree that max is likely unnecessary. -- Best regards ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ «If at first you don’t succeed, give up skydiving»