Re: [PATCH] usb: dwc2: gadget: fix ISOC frame overflow handling

[Minas Harutyunyan]

Hi John,

On 12/18/2018 6:35 PM, John Keeping wrote:
> Hi Minas,
> 
> On Fri, 14 Dec 2018 09:00:08 +0000
> Minas Harutyunyan <minas.harutyunyan@xxxxxxxxxxxx> wrote:
>> First of all, sorry for delayed answer.
>> Looks like similar issue seen by Andrzej Pietrasiewicz
>> <andrzej.p@xxxxxxxxxxx>: "dwc2 isochronous transfers issues". Same
>> feedback provided to Andrzej.
>>
>> I run tests on 4.20.0-rc4 in DDMA. By default IN ISOC traffic failed
>> because of BNA interrupts. It's happen because UAC2 requests count
>> set by default to 2. Our core and driver can't work in DDMA with
>> descriptor list length equal to 2. It's not possible on time prepare
>> next descriptors to avoid BNA interrupt.
>>
>> By changing UAC2_DEF_REQ_NUM to 4 all audio gadget tests passed
>> smoothly. Could you please apply this patch and run tests in DDMA
>> mode:
>>
>> diff --git a/drivers/usb/gadget/function/u_uac2.h
>> b/drivers/usb/gadget/function/u_uac2.h
>> index 8362ee572e1e..5e649259ab76 100644
>> --- a/drivers/usb/gadget/function/u_uac2.h
>> +++ b/drivers/usb/gadget/function/u_uac2.h
>> @@ -21,7 +21,7 @@
>>    #define UAC2_DEF_CCHMASK 0x3
>>    #define UAC2_DEF_CSRATE 64000
>>    #define UAC2_DEF_CSSIZE 2
>> -#define UAC2_DEF_REQ_NUM 2
>> +#define UAC2_DEF_REQ_NUM 4
>>
>>    struct f_uac2_opts {
>>           struct usb_function_instance    func_inst;
>>
>>
>> If it will OK on your side also then will switch to BDMA mode and
>> debug.
> 
> With DDMA enabled, I see the following error after the stream has been
> running for a while (anything from a few seconds to a few minutes):
> 
> -- >8 --
> [ 1798.836322] dwc2 ff580000.usb: dwc2_hsotg_ep_disable: called for ep0
> [ 1798.836329] dwc2 ff580000.usb: dwc2_hsotg_ep_disable: called for ep0
> [ 1798.851092] dwc2 ff580000.usb: new device is high-speed
> [ 1798.924461] dwc2 ff580000.usb: new device is high-speed
> [ 1798.982887] dwc2 ff580000.usb: new address 25
> [ 1799.002463] configfs-gadget gadget: high-speed config #1: config
> -- 8< --
> 
> On the host side (Linux 4.18.16 Intel xHCI), I see this logged at the
> same time:
> 
> -- >8 --
> [1735740.716242] retire_capture_urb: usb 1-2.2.7: frame 0 active: -71
> [1735740.716990] retire_capture_urb: usb 1-2.2.7: frame 0 active: -71
> [1735740.717906] retire_capture_urb: usb 1-2.2.7: frame 0 active: -71
> [1735740.718905] retire_capture_urb: usb 1-2.2.7: frame 0 active: -71
> [1735740.719916] retire_capture_urb: usb 1-2.2.7: frame 0 active: -71
> [1735740.720032] usb 1-2.2-port7: disabled by hub (EMI?), re-enabling...
> [1735740.720036] usb 1-2.2.7: USB disconnect, device number 28
> [1735740.937500] usb 1-2.2.7: new high-speed USB device number 29 using xhci_hcd
> -- 8< --
> 
> The device does then enumerate and works for a period of time before the
> same error happens again.
> 
 From logs not clear who initiate disconnect: host or device.  More 
probably host, after some errors in retire_capture_urb initiate 
disconnect. Do you have any idea?
Can't you connect device to host on same platform?
If root cause of disconnect by host is device issue, i.e. not able to 
send to host data packets in time then I need device side dmesg log with 
debug enabled. USB trace around the disconnect will help to debug.

Thanks,
Minas

> 
> Regards,
> John
>