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Date:   Tue, 18 Dec 2018 14:35:04 +0000
From:   John Keeping <john@metanate.com>
To:     Minas Harutyunyan <minas.harutyunyan@synopsys.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "arthur.petrosyan@synopsys.com" <arthur.petrosyan@synopsys.com>
Subject: Re: [PATCH] usb: dwc2: gadget: fix ISOC frame overflow handling
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Hi Minas,

On Fri, 14 Dec 2018 09:00:08 +0000
Minas Harutyunyan <minas.harutyunyan@synopsys.com> wrote:
> First of all, sorry for delayed answer.
> Looks like similar issue seen by Andrzej Pietrasiewicz 
> <andrzej.p@samsung.com>: "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.


Regards,
John