Re: [PATCH] usb: gadget: f_uac1: add IAD descriptor

[Chunfeng Yun]

On Fri, 2022-06-24 at 13:39 +0200, Greg Kroah-Hartman wrote:
> On Wed, Jun 22, 2022 at 04:57:57PM +0800, Chunfeng Yun wrote:
> > From: xin lin <xin.lin@xxxxxxxxxxxx>
> > 
> > Win10 can not enumerate composite device of UVC+UAC1+ADB without
> > IAD descriptor
> > in uac1.0, so add it.
> 
> I do not know what this means at all, sorry.  Can you please provide
> a
> better changelog text that describes what all of this is in more
> detail?
Ok, will add it in next version

> 
> 
> 
> > 
> > Signed-off-by: xin lin <xin.lin@xxxxxxxxxxxx>
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx>
> > ---
> >  drivers/usb/gadget/function/f_uac1.c | 21 +++++++++++++++++++++
> >  1 file changed, 21 insertions(+)
> > 
> > diff --git a/drivers/usb/gadget/function/f_uac1.c
> > b/drivers/usb/gadget/function/f_uac1.c
> > index 6f0e1d803dc2..8390207bc513 100644
> > --- a/drivers/usb/gadget/function/f_uac1.c
> > +++ b/drivers/usb/gadget/function/f_uac1.c
> > @@ -71,6 +71,17 @@ static inline struct f_uac1_opts
> > *g_audio_to_uac1_opts(struct g_audio *audio)
> >   * ALSA_Playback -> IT_3 -> OT_4 -> USB-IN
> >   */
> >  
> > +static struct usb_interface_assoc_descriptor iad_desc = {
> > +	.bLength = sizeof(iad_desc),
> > +	.bDescriptorType = USB_DT_INTERFACE_ASSOCIATION,
> > +
> > +	.bFirstInterface = 0,
> > +	.bInterfaceCount = 3,
> > +	.bFunctionClass = USB_CLASS_AUDIO,
> > +	.bFunctionSubClass = 0,
> > +	.bFunctionProtocol = UAC_VERSION_1,
> > +};
> > +
> >  /* B.3.1  Standard AC Interface Descriptor */
> >  static struct usb_interface_descriptor ac_interface_desc = {
> >  	.bLength =		USB_DT_INTERFACE_SIZE,
> > @@ -259,6 +270,7 @@ static struct uac_iso_endpoint_descriptor
> > as_iso_in_desc = {
> >  };
> >  
> >  static struct usb_descriptor_header *f_audio_desc[] = {
> > +	(struct usb_descriptor_header *)&iad_desc,
> 
> Why put this first?  Is that a requirement?
Yes, it's a requirement,
Interface Association Descriptor ECN:
"An interface association descriptor must be located before the set of
interface descriptors (including all alternate settings) for the
interfaces it associates."

> 
> >  	(struct usb_descriptor_header *)&ac_interface_desc,
> >  	(struct usb_descriptor_header *)&ac_header_desc,
> >  
> > @@ -293,6 +305,7 @@ static struct usb_descriptor_header
> > *f_audio_desc[] = {
> >  };
> >  
> >  enum {
> > +	STR_ASSOC,
> 
> Again, why first?
follow uac2 driver
> 
> >  	STR_AC_IF,
> >  	STR_USB_OUT_IT,
> >  	STR_USB_OUT_IT_CH_NAMES,
> > @@ -310,6 +323,7 @@ enum {
> >  
> >  static struct usb_string strings_uac1[] = {
> >  	/* [STR_AC_IF].s = DYNAMIC, */
> > +	[STR_ASSOC].s = "Source/Sink",
> >  	[STR_USB_OUT_IT].s = "Playback Input terminal",
> >  	[STR_USB_OUT_IT_CH_NAMES].s = "Playback Channels",
> >  	[STR_IO_OUT_OT].s = "Playback Output terminal",
> > @@ -1058,6 +1072,7 @@ static void setup_descriptor(struct
> > f_uac1_opts *opts)
> >  	as_out_header_desc.bTerminalLink = usb_out_it_desc.bTerminalID;
> >  	as_in_header_desc.bTerminalLink = usb_in_ot_desc.bTerminalID;
> >  
> > +	iad_desc.bInterfaceCount = 1;
> 
> Why this change?
FS, HS may be different, count up them again.

> 
> 
> >  	ac_header_desc->wTotalLength = cpu_to_le16(ac_header_desc-
> > >bLength);
> >  
> >  	if (EPIN_EN(opts)) {
> > @@ -1068,6 +1083,7 @@ static void setup_descriptor(struct
> > f_uac1_opts *opts)
> >  		if (FUIN_EN(opts))
> >  			len += in_feature_unit_desc->bLength;
> >  		ac_header_desc->wTotalLength = cpu_to_le16(len);
> > +		iad_desc.bInterfaceCount++;
> >  	}
> >  	if (EPOUT_EN(opts)) {
> >  		u16 len = le16_to_cpu(ac_header_desc->wTotalLength);
> > @@ -1077,9 +1093,11 @@ static void setup_descriptor(struct
> > f_uac1_opts *opts)
> >  		if (FUOUT_EN(opts))
> >  			len += out_feature_unit_desc->bLength;
> >  		ac_header_desc->wTotalLength = cpu_to_le16(len);
> > +		iad_desc.bInterfaceCount++;
> >  	}
> >  
> >  	i = 0;
> > +	f_audio_desc[i++] = USBDHDR(&iad_desc);
> 
> Again, why first?
It is a requirement as ECN says.

> 
> >  	f_audio_desc[i++] = USBDHDR(&ac_interface_desc);
> >  	f_audio_desc[i++] = USBDHDR(ac_header_desc);
> >  
> > @@ -1217,6 +1235,7 @@ static int f_audio_bind(struct
> > usb_configuration *c, struct usb_function *f)
> >  		}
> >  	}
> >  
> > +	iad_desc.iFunction = us[STR_ASSOC].id;
> >  	ac_interface_desc.iInterface = us[STR_AC_IF].id;
> >  	usb_out_it_desc.iTerminal = us[STR_USB_OUT_IT].id;
> >  	usb_out_it_desc.iChannelNames = us[STR_USB_OUT_IT_CH_NAMES].id;
> > @@ -1302,6 +1321,8 @@ static int f_audio_bind(struct
> > usb_configuration *c, struct usb_function *f)
> >  	status = usb_interface_id(c, f);
> >  	if (status < 0)
> >  		goto err_free_fu;
> > +
> > +	iad_desc.bFirstInterface = status;
> 
> Shouldn't this be needed without your change?
Need update, it's not always 0.

Thanks a lot

> 
> thanks,
> 
> greg k-h