Messages in this thread | | | Subject | Re: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated | From | Sergei Shtylyov <> | Date | Mon, 23 May 2016 19:46:26 +0300 |
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On 05/23/2016 06:19 PM, Andrew Goodbody 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@cambrionix.com> >>>>>> 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". > > 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
Yes, thank you.
MBR, Sergei
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