Re: [PATCH 2/2] usb: gadget: f_uac2: fix calculation of uac2->p_interval

[Daniel Mack <daniel@zonque.org>]

On 07/27/2015 08:51 AM, Peter Chen wrote:
> The p_interval should be less if the 'bInterval' at the descriptor
> is larger, eg, if 'bInterval' is 5 for HS, the p_interval should be
> 8000 / 16 = 500.
> 
> It fixes the patch 9bb87f16 "usb: gadget: f_uac2: send reasonably
> sized packets"
> 

Acked-by: Daniel Mack <zonque@gmail.com>


Thanks for spotting this!

Daniel


> Cc: Daniel Mack <zonque@gmail.com>
> Cc: <stable@vger.kernel.org> #v3.18+
> Signed-off-by: Peter Chen <peter.chen@freescale.com>
> ---
>  drivers/usb/gadget/function/f_uac2.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c
> index 51ca32d..4bd9a8e 100644
> --- a/drivers/usb/gadget/function/f_uac2.c
> +++ b/drivers/usb/gadget/function/f_uac2.c
> @@ -1191,14 +1191,14 @@ afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
>  			factor = 1000;
>  		} else {
>  			ep_desc = &hs_epin_desc;
> -			factor = 125;
> +			factor = 8000;
>  		}
>  
>  		/* pre-compute some values for iso_complete() */
>  		uac2->p_framesize = opts->p_ssize *
>  				    num_channels(opts->p_chmask);
>  		rate = opts->p_srate * uac2->p_framesize;
> -		uac2->p_interval = (1 << (ep_desc->bInterval - 1)) * factor;
> +		uac2->p_interval = factor / (1 << (ep_desc->bInterval - 1));
>  		uac2->p_pktsize = min_t(unsigned int, rate / uac2->p_interval,
>  					prm->max_psize);
>  
>