From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755664AbcEWOhM (ORCPT ); Mon, 23 May 2016 10:37:12 -0400 Received: from mail-lf0-f45.google.com ([209.85.215.45]:35956 "EHLO mail-lf0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752863AbcEWOhI (ORCPT ); Mon, 23 May 2016 10:37:08 -0400 Subject: Re: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated To: Andrew Goodbody , "b-liu@ti.com" References: <1464004844-26553-1-git-send-email-andrew.goodbody@cambrionix.com> <1464004844-26553-3-git-send-email-andrew.goodbody@cambrionix.com> <6b25b4a5cc104ea0adc5bd006040529b@SEHSTE15D2BE2.hs20.net> Cc: "gregkh@linuxfoundation.org" , "linux-usb@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" From: Sergei Shtylyov Organization: Cogent Embedded Message-ID: <6a1d9c4c-5501-bf4f-9ddc-9ffe6e2371a1@cogentembedded.com> Date: Mon, 23 May 2016 17:37:03 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/23/2016 04:40 PM, Sergei Shtylyov wrote: >>>> Ensure that the endpoint is stopped by clearing REQPKT before clearing >>>> DATAERR_NAKTIMEOUT before rotating the queue on the dedicated bulk >>>> endpoint. >>>> This addresses an issue where a race could result in the endpoint >>>> receiving data before it was reprogrammed resulting in a warning about >>>> such data from musb_rx_reinit before it was thrown away. >>>> The data thrown away was a valid packet that had been correctly ACKed >>>> which meant the host and device got out of sync. >>>> >>>> Signed-off-by: Andrew Goodbody >>>> Cc: stable@vger.kernel.org >>>> --- >>>> V2 added comment about clearing REQPKT before DATAERR_NAKTIMEOUT >>>> >>>> drivers/usb/musb/musb_host.c | 6 ++++++ >>>> 1 file changed, 6 insertions(+) >>>> >>>> diff --git a/drivers/usb/musb/musb_host.c >>>> b/drivers/usb/musb/musb_host.c index 2966596..676cb98 100644 >>>> --- a/drivers/usb/musb/musb_host.c >>>> +++ b/drivers/usb/musb/musb_host.c >>>> @@ -997,6 +997,12 @@ static void musb_bulk_nak_timeout(struct musb >>> *musb, struct musb_hw_ep *ep, >>>> /* clear nak timeout bit */ >>>> rx_csr = musb_readw(epio, MUSB_RXCSR); >>>> rx_csr |= MUSB_RXCSR_H_WZC_BITS; >>>> + /* >>>> + * Need to stop the transaction by clearing REQPKT before >>> >>> Transcation? Maybe transfer? >> >> The quote from the TRM is "If the DATAERR_NAKTIMEOUT bit is set, the >> controller can be directed either to continue trying this transaction (until >> it times out again) by clearing the DATAERR_NAKTIMEOUT bit or to abort the >> transaction by clearing REQPKT bit before clearing the DATAERR_NAKTIMEOUT bit." >> So 'transaction' is correct. > > OK. > >>>> + * DATAERR_NAKTIMEOUT ref TRM section 16.3.8.2.2.1.2 >>> >>> Which TRM? Do you understand that the MUSB core is used by multiple >>> SoCs? >>> I'd recommend referring just to the "abstract" manual or the MUSB >>> programmer's guide (section 9.2.2 if you want an exact ref.). > >> That would be the AM335x Sitara Processors TRM. I don't have the MUSB >> programmer's guide, is it available online somewhere? > > AFAIK, no. > >> I do not understand what you mean by the "abstract" manual. > > Just saying "the manual" or "the manuals". > >> Would you be OK with "ref MUSB Programmer's Guide section 9.2.2" > > Yes. The full document name is "MUSBMHDRC USB 2.0 HIGH-SPEED DUAL-ROLE CONTROLLER Programmer’s Guide". >> Andrew >> >>> [...] MBR, Sergei