Re: [PATCH v2 1/2] usb: gadget: f_uac2: Stop endpoint before enabling it.

[Felipe Balbi <balbi@kernel.org>]

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Hi,

Pawel Laszczak <pawell@cadence.com> writes:
> From: Pawel Laszczak <pawell@cadence.com>
>
> Patch adds disabling endpoint before enabling it during changing
> alternate setting. Lack of this functionality causes that in some
> cases uac2 queue the same request multiple time.
> Such situation can occur when host send set interface with
> alternate setting 1 twice.

Which host is doing that?

> Signed-off-by: Pawel Laszczak <pawell@cadence.com>
>
> ---
> Changelog:
> v2:
> - moved disabling endpoint into u_audio_start_playback
>
>  drivers/usb/gadget/function/u_audio.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
> index 265c4d805f81..c4bbc9decaba 100644
> --- a/drivers/usb/gadget/function/u_audio.c
> +++ b/drivers/usb/gadget/function/u_audio.c
> @@ -401,6 +401,10 @@ int u_audio_start_playback(struct g_audio *audio_dev)
>  
>  	ep = audio_dev->in_ep;
>  	prm = &uac->p_prm;
> +
> +	if (prm->ep_enabled)
> +		u_audio_stop_capture(audio_dev);

this looks to be a bug in f_uac2.c::afunc_set_alt(), actually. Note how
e.g. f_obex.c::obex_set_alt() is implemented:

> } else if (intf == obex->data_id) {
> 	if (alt > 1)
> 		goto fail;
>
> 	if (obex->port.in->enabled) {

if interface is already enabled...

> 		dev_dbg(&cdev->gadget->dev,
> 			"reset obex ttyGS%d\n", obex->port_num);
> 		gserial_disconnect(&obex->port);

...disable it first...

> 	}
>
> 	if (!obex->port.in->desc || !obex->port.out->desc) {
> 		dev_dbg(&cdev->gadget->dev,
> 			"init obex ttyGS%d\n", obex->port_num);
> 		if (config_ep_by_speed(cdev->gadget, f,
> 				       obex->port.in) ||
> 		    config_ep_by_speed(cdev->gadget, f,
> 				       obex->port.out)) {

...before configuring endpoints again

-- 
balbi

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