Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1405310 > unrolled thread

[PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated

Started byAndrew Goodbody <andrew.goodbody@cambrionix.com>
First post2016-05-23 14:10 +0200
Last post2016-05-23 18:50 +0200
Articles 7 — 2 participants

Back to article view | Back to linux.kernel

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated Andrew Goodbody <andrew.goodbody@cambrionix.com> - 2016-05-23 14:10 +0200
    Re: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is  rotated Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2016-05-23 14:40 +0200
      RE: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is  rotated Andrew Goodbody <andrew.goodbody@cambrionix.com> - 2016-05-23 15:30 +0200
        Re: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is  rotated Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2016-05-23 15:50 +0200
          Re: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is  rotated Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2016-05-23 16:40 +0200
            RE: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is  rotated Andrew Goodbody <andrew.goodbody@cambrionix.com> - 2016-05-23 17:30 +0200
              Re: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is  rotated Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> - 2016-05-23 18:50 +0200

#1405310 — [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated

FromAndrew Goodbody <andrew.goodbody@cambrionix.com>
Date2016-05-23 14:10 +0200
Subject[PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated
Message-ID<rBWQi-5Ct-21@gated-at.bofh.it>
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
+		 * DATAERR_NAKTIMEOUT ref TRM section 16.3.8.2.2.1.2
+		 */
+		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);
 
-- 
2.7.4

[toc] | [next] | [standalone]

#1405323 — Re: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated

FromSergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Date2016-05-23 14:40 +0200
SubjectRe: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated
Message-ID<rBXjk-5NQ-3@gated-at.bofh.it>
In reply to#1405310
Hello.

On 5/23/2016 3:00 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?

> +		 * 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.).

[...]

MBR, Sergei

[toc] | [prev] | [next] | [standalone]

#1405364 — RE: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated

FromAndrew Goodbody <andrew.goodbody@cambrionix.com>
Date2016-05-23 15:30 +0200
SubjectRE: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated
Message-ID<rBY5H-6pa-1@gated-at.bofh.it>
In reply to#1405323
> From: Sergei Shtylyov [mailto:sergei.shtylyov@cogentembedded.com]
> 
> Hello.
> 
> On 5/23/2016 3:00 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.

> > +		 * 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? I do not understand what you mean by the "abstract" manual. Would you be OK with "ref MUSB Programmer's Guide section 9.2.2"

Andrew

> [...]
> 
> MBR, Sergei

[toc] | [prev] | [next] | [standalone]

#1405382 — Re: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated

FromSergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Date2016-05-23 15:50 +0200
SubjectRe: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated
Message-ID<rBYp3-6vy-11@gated-at.bofh.it>
In reply to#1405364
On 5/23/2016 4:26 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. However, that spec calls the bit just "NAK Timeout" in this context, 
not DATAERR_NAKTIMEOUT. Overall, this spec. uses CamelCase for the register 
bit names (I recall dbrownell complaining over that and uppercase all the bit 
names in my patches :-).

> Andrew
>
>> [...]

MBR, Sergei

[toc] | [prev] | [next] | [standalone]

#1405412 — Re: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated

FromSergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Date2016-05-23 16:40 +0200
SubjectRe: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated
Message-ID<rBZbs-712-21@gated-at.bofh.it>
In reply to#1405382
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@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".

>> Andrew
>>
>>> [...]

MBR, Sergei

[toc] | [prev] | [next] | [standalone]

#1405451 — RE: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated

FromAndrew Goodbody <andrew.goodbody@cambrionix.com>
Date2016-05-23 17:30 +0200
SubjectRE: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated
Message-ID<rBZXQ-7DR-13@gated-at.bofh.it>
In reply to#1405412
> From: Sergei Shtylyov [mailto:sergei.shtylyov@cogentembedded.com]
> 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@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

[toc] | [prev] | [next] | [standalone]

#1405505 — Re: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated

FromSergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Date2016-05-23 18:50 +0200
SubjectRe: [PATCH V2 2/2] usb: musb: Stop bulk endpoint while queue is rotated
Message-ID<rC1df-8iS-1@gated-at.bofh.it>
In reply to#1405451
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

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web