> From: Sergei Shtylyov [mailto:sergei.shtylyov@xxxxxxxxxxxxxxxxxx] > 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 > <andrew.goodbody@xxxxxxxxxxxxxx> > >>>> Cc: stable@xxxxxxxxxxxxxxx > >>>> --- > >>>> 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". I moved the comment up to replace the one at the top so the patch now looks like this if (is_in) { dma = is_dma_capable() ? ep->rx_channel : NULL; - /* clear nak timeout bit */ + /* + * Need to stop the transaction by clearing REQPKT first + * then the NAK Timeout bit ref MUSBMHDRC USB 2.0 HIGH-SPEED + * DUAL-ROLE CONTROLLER Programmer's Guide, section 9.2.2 + */ rx_csr = musb_readw(epio, MUSB_RXCSR); rx_csr |= MUSB_RXCSR_H_WZC_BITS; + rx_csr &= ~MUSB_RXCSR_H_REQPKT; + musb_writew(epio, MUSB_RXCSR, rx_csr); rx_csr &= ~MUSB_RXCSR_DATAERROR; musb_writew(epio, MUSB_RXCSR, rx_csr); Are you OK with that now? Andrew -- 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
