linux-kernel - Re: [PATCHv3 2/4] usb: gadget: replace "is_dualspeed" with "max

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Message-ID: <20110825125306.GP22532@legolas.emea.dhcp.ti.com>
Date:	Thu, 25 Aug 2011 15:53:07 +0300
From:	Felipe Balbi <balbi@...com>
To:	Michal Nazarewicz <mnazarewicz@...gle.com>
Cc:	Felipe Balbi <balbi@...com>,
	Alan Stern <stern@...land.harvard.edu>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	Yang Rui Rui <ruirui.r.yang@...to.com>,
	Dave Young <hidave.darkstar@...il.com>,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv3 2/4] usb: gadget: replace "is_dualspeed" with
 "max_speed"

Hi,

On Thu, Aug 25, 2011 at 02:46:55PM +0200, Michal Nazarewicz wrote:
> On Thu, 25 Aug 2011 01:04:19 +0200, Felipe Balbi <balbi@...com> wrote:
> >there's one catch. As of today, we always start UDCs with data pullups
> >connected, which means that we could connect to a host even before a
> >gadget driver is loaded. My point in moving to udc_start/udc_stop is
> >that the above would be take care of. See udc-core.c: [...]
> 
> Honestly I'm not quite sure why udc_start/udc_stop is needed here.  Even
> without those the UDC driver can start with all hw disabled and turn it
> on only after the gadget driver's bind callback finishes.
> 
> >If all UDCs are converted to udc_start()/udc_stop() we get the guarantee
> >that they will only conect to host after gadget driver is fully loaded
> >for free.
> 
> >We can also, finally, properly use the usb_function_deactivate/
> >usb_function_activate properly. So for each registered function,
> >composite.c calls usb_function_deactivate() and function is _required_
> >to call usb_function_activate when it's ready.
> 
> I'm not really sure why that would be beneficial.  Also, it would still
> require disconnect-connect cycle if some function decides to (de)activate
> itself while gadget is connected.
> 
> >Then, when on gadget driver's bind() we can take this kind of speed
> >decision and pass that on to UDC driver.
> 
> So can we leave things as they are for now and wait for UDCs to be
> converted
> and once this is done, do all kinds of magic we want in copomiset's bind
> callback?

sure.

-- 
balbi

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