linux-kernel - Re: [PATCH v5 01/46] usb: gadget: encapsulate endpoint claiming mechanism

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Date:	Thu, 20 Aug 2015 11:48:08 -0500
From:	Felipe Balbi <balbi@...com>
To:	Robert Baldyga <r.baldyga@...kerion.com>
CC:	<balbi@...com>, Robert Baldyga <r.baldyga@...sung.com>,
	<gregkh@...uxfoundation.org>, <Peter.Chen@...escale.com>,
	<johnyoun@...opsys.com>, <dahlmann.thomas@...or.de>,
	<nicolas.ferre@...el.com>, <cernekee@...il.com>,
	<leoli@...escale.com>, <daniel@...que.org>,
	<haojian.zhuang@...il.com>, <robert.jarzmik@...e.fr>,
	<michal.simek@...inx.com>, <devel@...verdev.osuosl.org>,
	<linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
	<linux-omap@...r.kernel.org>, <linux-geode@...ts.infradead.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linuxppc-dev@...ts.ozlabs.org>, <andrzej.p@...sung.com>,
	<m.szyprowski@...sung.com>, <stern@...land.harvard.edu>,
	<petr.cvek@....cz>
Subject: Re: [PATCH v5 01/46] usb: gadget: encapsulate endpoint claiming
 mechanism

On Thu, Aug 20, 2015 at 06:28:14PM +0200, Robert Baldyga wrote:
> Hi Felipe,
> 
> On 08/20/2015 05:35 PM, Felipe Balbi wrote:
> [...]
> >just letting you know that this regresses all gadget drivers making them
> >try to disable previously disabled endpoints and enable previously
> >enabled endpoints.
> >
> >I have a possible fix (see below) but then it shows a problem on the
> >host side when using with g_zero (see further below):
> >
> >commit 3b8932100aacb6cfbffe288ca93025d8b8430c00
> >Author: Felipe Balbi <balbi@...com>
> >Date:   Wed Aug 19 18:05:27 2015 -0500
> >
> >     usb: gadget: fix ep->claimed lifetime
> >
> >     In order to fix a regression introduced by commit
> >     cc476b42a39d ("usb: gadget: encapsulate endpoint
> >     claiming mechanism") we have to introduce a simple
> >     helper to check if a particular is enabled or not.
> >
> >     After that, we need to move ep->claimed lifetime to
> >     usb_ep_enable() and usb_ep_disable() since those
> >     are the only functions which actually enable and
> >     disable endpoints.
> >
> >     A follow-up patch will come to drop all driver_data
> >     checks from function drivers, since those are, now,
> >     pointless.
> >
> >     Fixes: cc476b42a39d ("usb: gadget: encapsulate endpoint
> >     	claiming mechanism")
> >     Cc: Robert Baldyga <r.baldyga@...sung.com>
> >     Signed-off-by: Felipe Balbi <balbi@...com>
> >
> >diff --git a/drivers/usb/gadget/epautoconf.c b/drivers/usb/gadget/epautoconf.c
> >index 978435a51038..ad45070cd76f 100644
> >--- a/drivers/usb/gadget/epautoconf.c
> >+++ b/drivers/usb/gadget/epautoconf.c
> >@@ -126,7 +126,6 @@ found_ep:
> >  	ep->address = desc->bEndpointAddress;
> >  	ep->desc = NULL;
> >  	ep->comp_desc = NULL;
> >-	ep->claimed = true;
> 
> Removing this line causes autoconfig can return the same endpoint many
> times. This probably causes problems with g_zero.
> 
> I will try to fix it ASAP.

I was considering the same thing, but the lifetime of ->claimed doesn't
look correct to me either way. Note that once the flag is enabled, it
won't get disabled by most gadget drivers.

-- 
balbi

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