Re: [PATCH v4 1/1] usb: gadget: f_uac2: finalize wMaxPacketSize according to bandwidth

[Daniel Mack <daniel@zonque.org>]

On 07/28/2015 03:38 AM, Peter Chen wrote:

> diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
> index 5318615..6a8e0d2 100644
> --- a/drivers/usb/gadget/function/f_uac2.c
> +++ b/drivers/usb/gadget/function/f_uac2.c
> @@ -975,6 +975,31 @@ free_ep(struct uac2_rtd_params *prm, struct usb_ep *ep)
>  			"%s:%d Error!\n", __func__, __LINE__);
>  }
>  
> +static void set_ep_max_packet_size (struct f_uac2_opts *uac2_opts,
> +	struct usb_endpoint_descriptor *ep_desc, unsigned int factor)

scripts/checkpatch.pl will complain about a stray space before '(' and
wrong indentation. Also, uac2_opts can be const.

> +{
> +	int chmask;
> +	int srate;
> +	int ssize;

These can be put in one line.

> +	u16 max_packet_size;
> +
> +	if (ep_desc == &fs_epin_desc || ep_desc == &hs_epin_desc) {
> +		chmask = uac2_opts->p_chmask;	
> +		srate = uac2_opts->p_srate;
> +		ssize = uac2_opts->p_ssize;
> +	} else {
> +		WARN_ON (ep_desc != &fs_epout_desc && ep_desc != &hs_epout_desc);

I would rather pass a boolean flag called 'is_playback' than checking
the input parameter like this. But I forgot this detail in my proposal,
I admit.

Apart from that, I like the patch.


Thanks,
Daniel



> +		chmask = uac2_opts->c_chmask;
> +		srate = uac2_opts->c_srate;
> +		ssize = uac2_opts->c_ssize;
> +	}
> +
> +	max_packet_size = num_channels(chmask) * ssize *
> +	       	DIV_ROUND_UP(srate, factor / (1 << (ep_desc->bInterval - 1)));
> +	ep_desc->wMaxPacketSize = min(cpu_to_le16(max_packet_size),
> +				ep_desc->wMaxPacketSize);
> +}
> +
>  static int
>  afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
>  {
> @@ -1070,10 +1095,14 @@ afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
>  	uac2->p_prm.uac2 = uac2;
>  	uac2->c_prm.uac2 = uac2;
>  
> +	/* Calculate wMaxPacketSize according to audio bandwidth */
> +	set_ep_max_packet_size(uac2_opts, &fs_epin_desc, 1000);
> +	set_ep_max_packet_size(uac2_opts, &fs_epout_desc, 1000);
> +	set_ep_max_packet_size(uac2_opts, &hs_epin_desc, 8000);
> +	set_ep_max_packet_size(uac2_opts, &hs_epout_desc, 8000);
> +
>  	hs_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress;
> -	hs_epout_desc.wMaxPacketSize = fs_epout_desc.wMaxPacketSize;
>  	hs_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress;
> -	hs_epin_desc.wMaxPacketSize = fs_epin_desc.wMaxPacketSize;
>  
>  	ret = usb_assign_descriptors(fn, fs_audio_desc, hs_audio_desc, NULL);
>  	if (ret)
>