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

[Greg Kroah-Hartman]

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?



> 
> 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?

>  	(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?

>  	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?


>  	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?

>  	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?

thanks,

greg k-h