From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <stable-owner@vger.kernel.org>
Received: from svenfoo.org ([82.94.215.22]:54707 "EHLO mail.zonque.de"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1751366AbbG1Jhq (ORCPT <rfc822;stable@vger.kernel.org>);
	Tue, 28 Jul 2015 05:37:46 -0400
Subject: Re: [PATCH v4 1/1] usb: gadget: f_uac2: finalize wMaxPacketSize
 according to bandwidth
To: Peter Chen <peter.chen@freescale.com>, balbi@ti.com
References: <1438047504-19786-1-git-send-email-peter.chen@freescale.com>
 <55B74BCD.3030401@zonque.org>
Cc: linux-usb@vger.kernel.org, andrzej.p@samsung.com,
	Daniel Mack <zonque@gmail.com>, tiwai@suse.de,
	stable@vger.kernel.org, Alan Stern <stern@rowland.harvard.edu>
From: Daniel Mack <daniel@zonque.org>
Message-ID: <55B74D68.8060506@zonque.org>
Date: Tue, 28 Jul 2015 11:37:44 +0200
MIME-Version: 1.0
In-Reply-To: <55B74BCD.3030401@zonque.org>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Sender: stable-owner@vger.kernel.org
List-ID: <stable.vger.kernel.org>

On 07/28/2015 11:30 AM, Daniel Mack wrote:
> On 07/28/2015 03:38 AM, Peter Chen wrote:
>> +static void set_ep_max_packet_size (struct f_uac2_opts *uac2_opts,
>> +	struct usb_endpoint_descriptor *ep_desc, unsigned int factor)
>> +{
>> +	int chmask;
>> +	int srate;
>> +	int ssize;
>> +	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);
>> +		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);
>> +}
> 
> Thinking about it again, it would probably be nicer to make this
> function return wMaxPacketSize directly:

Ah, no, that doesn't make sense, sorry. We need bInterval and the
current value of wMaxPacketSize as well. Just stick with your current
approach then :)