linux-kernel - Re: [PATCH v2 1/1] usb: dwc2: gadget: parity fix in isochronous mode

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Date:	Thu, 10 Sep 2015 02:24:56 +0000
From:	John Youn <John.Youn@...opsys.com>
To:	Roman Bacik <rbacik@...adcom.com>,
	John Youn <John.Youn@...opsys.com>,
	Scott Branden <sbranden@...adcom.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH v2 1/1] usb: dwc2: gadget: parity fix in isochronous mode

On 9/9/2015 7:16 PM, Roman Bacik wrote:
>> -----Original Message-----
>> From: John Youn [mailto:John.Youn@...opsys.com]
>> Sent: September-09-15 7:11 PM
>> To: Roman Bacik; John Youn; Scott Branden; Greg Kroah-Hartman; linux-
>> usb@...r.kernel.org
>> Cc: linux-kernel@...r.kernel.org; bcm-kernel-feedback-list
>> Subject: Re: [PATCH v2 1/1] usb: dwc2: gadget: parity fix in isochronous mode
>>
>> On 9/9/2015 11:16 AM, Roman Bacik wrote:
>>>> -----Original Message-----
>>>> From: John Youn [mailto:John.Youn@...opsys.com]
>>>> Sent: September-03-15 11:53 PM
>>>> To: Scott Branden; John Youn; Greg Kroah-Hartman; linux-
>>>> usb@...r.kernel.org; Roman Bacik
>>>> Cc: linux-kernel@...r.kernel.org; bcm-kernel-feedback-list
>>>> Subject: Re: [PATCH v2 1/1] usb: dwc2: gadget: parity fix in
>>>> isochronous mode
>>>>
>>>> On 8/31/2015 9:17 AM, Scott Branden wrote:
>>>>> From: Roman Bacik <rbacik@...adcom.com>
>>>>>
>>>>> USB OTG driver in isochronous mode has to set the parity of the
>>>>> receiving microframe. The parity is set to even by default. This
>>>>> causes problems for an audio gadget, if the host starts transmitting
>>>>> on odd
>>>> microframes.
>>>>>
>>>>> This fix uses Incomplete Periodic Transfer interrupt to toggle
>>>>> between even and odd parity until the Transfer Complete interrupt is
>> received.
>>>>>
>>>>> Signed-off-by: Roman Bacik <rbacik@...adcom.com>
>>>>> Reviewed-by: Abhinav Ratna <aratna@...adcom.com>
>>>>> Reviewed-by: Srinath Mannam <srinath.mannam@...adcom.com>
>>>>> Signed-off-by: Scott Branden <sbranden@...adcom.com>
>>>>> ---
>>>>>  drivers/usb/dwc2/core.h   |  1 +
>>>>>  drivers/usb/dwc2/gadget.c | 51
>>>> ++++++++++++++++++++++++++++++++++++++++++++++-
>>>>>  drivers/usb/dwc2/hw.h     |  1 +
>>>>>  3 files changed, 52 insertions(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h index
>>>>> 0ed87620..a5634fd 100644
>>>>> --- a/drivers/usb/dwc2/core.h
>>>>> +++ b/drivers/usb/dwc2/core.h
>>>>> @@ -150,6 +150,7 @@ struct s3c_hsotg_ep {
>>>>>  	unsigned int            periodic:1;
>>>>>  	unsigned int            isochronous:1;
>>>>>  	unsigned int            send_zlp:1;
>>>>> +	unsigned int            has_correct_parity:1;
>>>>>
>>>>>  	char                    name[10];
>>>>>  };
>>>>> diff --git a/drivers/usb/dwc2/gadget.c b/drivers/usb/dwc2/gadget.c
>>>>> index 4d47b7c..fac3e2f 100644
>>>>> --- a/drivers/usb/dwc2/gadget.c
>>>>> +++ b/drivers/usb/dwc2/gadget.c
>>>>> @@ -1954,6 +1954,7 @@ static void s3c_hsotg_epint(struct dwc2_hsotg
>>>> *hsotg, unsigned int idx,
>>>>>  		ints &= ~DXEPINT_XFERCOMPL;
>>>>>
>>>>>  	if (ints & DXEPINT_XFERCOMPL) {
>>>>> +		hs_ep->has_correct_parity = 1;
>>>>>  		if (hs_ep->isochronous && hs_ep->interval == 1) {
>>>>>  			if (ctrl & DXEPCTL_EOFRNUM)
>>>>>  				ctrl |= DXEPCTL_SETEVENFR;
>>>>> @@ -2316,7 +2317,8 @@ void s3c_hsotg_core_init_disconnected(struct
>>>> dwc2_hsotg *hsotg,
>>>>>  		GINTSTS_CONIDSTSCHNG | GINTSTS_USBRST |
>>>>>  		GINTSTS_RESETDET | GINTSTS_ENUMDONE |
>>>>>  		GINTSTS_OTGINT | GINTSTS_USBSUSP |
>>>>> -		GINTSTS_WKUPINT,
>>>>> +		GINTSTS_WKUPINT |
>>>>> +		GINTSTS_INCOMPL_SOIN | GINTSTS_INCOMPL_SOOUT,
>>>>>  		hsotg->regs + GINTMSK);
>>>>>
>>>>>  	if (using_dma(hsotg))
>>>>> @@ -2581,6 +2583,52 @@ irq_retry:
>>>>>  		s3c_hsotg_dump(hsotg);
>>>>>  	}
>>>>>
>>>>> +	if (gintsts & GINTSTS_INCOMPL_SOIN) {
>>>>> +		u32 idx, epctl_reg, ctrl;
>>>>> +		struct s3c_hsotg_ep *hs_ep;
>>>>> +
>>>>> +		dev_dbg(hsotg->dev, "%s: GINTSTS_INCOMPL_SOIN\n",
>>>> __func__);
>>>>> +		for (idx = 1; idx < MAX_EPS_CHANNELS; idx++) {
>>>>
>>>> Valid endpoints are only up to hsotg->num_of_eps so this might crash
>>>> on certain configurations.
>>>>
>>>> Also, have you tried to find the endpoint which caused the incomplete
>>>> interrupt by reading the control registers as described in the databook?
>>>>
>>>
>>> We are using procedure based on description from this source:
>>>
>>> Synopsys, Inc. SolvNet 527
>>> DesignWare.com
>>> 3.00a
>>> April 2012
>>> USB 2.0 Hi-Speed On-The-Go (OTG) Databook Isochronous Endpoints in
>>> DWC_otg Slave Mode
>>>
>>> Synopsys databook is not in a public domain to quote the exact paragraph
>> here. You can find it in Chapter E, pp 526-527. There is no register in this
>> databook, which would provide information about the source endpoint of
>> the incomplete interrupt, as you have described.
>>>
>>> Please, provide an exact reference and possibly enough information that
>> we can turn it into a working code.
>>>
>>
>> You can check the source of the interrupt by reading the DSTS and ep control
>> registers as described in the databook page 526, last bullet, and 527 first
>> bullet.
>>
>> John
>>
> 
> Yes, that is exactly what we are doing what is described in the last bullet of 526 and the first two bullets of page 527. So what is the problem?
> 

Maybe I missed it. Where exactly are you doing it like it says in
these two paragraphs?

Quote:

GINTSTS.incompISOIN is a global interrupt. Therefore, when more
than one isochronous endpoints is active, then the application
must determine which isochronous IN endpoints have incomplete
data.

To accomplish this, read DSTS and DIEPCTLn for all isochronous
endpoints. If DSTS.SOFFN[0] =DIEPCTLn.EO_FrNum (Bit 16),then that
endpoint has an incomplete transfer

John




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