From: Roger Quadros <rogerq@ti.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Peter Chen <peter.chen@freescale.com>,
gregkh@linuxfoundation.org, balbi@ti.com,
dan.j.williams@intel.com, jun.li@freescale.com,
mathias.nyman@linux.intel.com, tony@atomide.com,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-omap@vger.kernel.org
Subject: Re: [RFC][PATCH v2 06/13] usb: hcd: Add hcd add/remove functions for OTG use
Date: Tue, 21 Apr 2015 10:02:30 +0300 [thread overview]
Message-ID: <5535F606.2070000@ti.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1504200948280.1321-100000@iolanthe.rowland.org>
On 20/04/15 16:56, Alan Stern wrote:
> On Mon, 20 Apr 2015, Roger Quadros wrote:
>
>>> I don't understand this. Why do you want to defer the add/remove if
>>> the device is OTG? Don't host controller drivers expect these things
>>> to execute synchronously?
>>
>> Sorry for the wrong information. We actually defer only the add as the
>> OTG state machine might not yet be in Host ready mode.
>> The remove is always synchronous and we ensure that the HCD is removed
>> when usb_otg_unregister_hcd() returns.
>
> That's okay then, but it does leave one potential hole. What happens
> if usb_add_hcd() is deferred for so long that usb_remove_hcd() gets
> called before the add can complete?
We keep track of the HCD state in the OTG state machine and if it was not
yet added then _usb_remove_hcd() is not called during usb_otg_unregister_hcd()
in the usb_remove_hcd() call.
cheers,
-roger
WARNING: multiple messages have this Message-ID (diff)
From: Roger Quadros <rogerq@ti.com>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: Peter Chen <peter.chen@freescale.com>,
<gregkh@linuxfoundation.org>, <balbi@ti.com>,
<dan.j.williams@intel.com>, <jun.li@freescale.com>,
<mathias.nyman@linux.intel.com>, <tony@atomide.com>,
<linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-omap@vger.kernel.org>
Subject: Re: [RFC][PATCH v2 06/13] usb: hcd: Add hcd add/remove functions for OTG use
Date: Tue, 21 Apr 2015 10:02:30 +0300 [thread overview]
Message-ID: <5535F606.2070000@ti.com> (raw)
In-Reply-To: <Pine.LNX.4.44L0.1504200948280.1321-100000@iolanthe.rowland.org>
On 20/04/15 16:56, Alan Stern wrote:
> On Mon, 20 Apr 2015, Roger Quadros wrote:
>
>>> I don't understand this. Why do you want to defer the add/remove if
>>> the device is OTG? Don't host controller drivers expect these things
>>> to execute synchronously?
>>
>> Sorry for the wrong information. We actually defer only the add as the
>> OTG state machine might not yet be in Host ready mode.
>> The remove is always synchronous and we ensure that the HCD is removed
>> when usb_otg_unregister_hcd() returns.
>
> That's okay then, but it does leave one potential hole. What happens
> if usb_add_hcd() is deferred for so long that usb_remove_hcd() gets
> called before the add can complete?
We keep track of the HCD state in the OTG state machine and if it was not
yet added then _usb_remove_hcd() is not called during usb_otg_unregister_hcd()
in the usb_remove_hcd() call.
cheers,
-roger
next prev parent reply other threads:[~2015-04-21 7:02 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-14 10:41 [RFC][PATCH v2 00/13] USB: OTG/DRD Core functionality Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-14 10:41 ` [RFC][PATCH v2 01/13] usb: otg-fsm: Add documentation for struct otg_fsm Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-16 11:32 ` Peter Chen
2015-04-16 11:32 ` Peter Chen
2015-04-17 8:45 ` Roger Quadros
2015-04-17 8:45 ` Roger Quadros
[not found] ` <1429008120-5395-1-git-send-email-rogerq-l0cyMroinI0@public.gmane.org>
2015-04-14 10:41 ` [RFC][PATCH v2 02/13] usb: otg-fsm: support multiple instances Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-16 11:36 ` Peter Chen
2015-04-16 11:36 ` Peter Chen
2015-04-16 11:58 ` Roger Quadros
2015-04-16 11:58 ` Roger Quadros
2015-04-16 12:06 ` Peter Chen
2015-04-16 12:06 ` Peter Chen
2015-04-14 10:41 ` [RFC][PATCH v2 04/13] usb: gadget: add usb_gadget_start/stop() Roger Quadros
2015-04-14 10:41 ` Roger Quadros
[not found] ` <1429008120-5395-5-git-send-email-rogerq-l0cyMroinI0@public.gmane.org>
2015-04-16 11:48 ` Peter Chen
2015-04-16 11:48 ` Peter Chen
2015-04-16 12:07 ` Roger Quadros
2015-04-16 12:07 ` Roger Quadros
[not found] ` <552FA60D.5030707-l0cyMroinI0@public.gmane.org>
2015-04-16 12:12 ` Peter Chen
2015-04-16 12:12 ` Peter Chen
2015-04-14 10:41 ` [RFC][PATCH v2 06/13] usb: hcd: Add hcd add/remove functions for OTG use Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-17 2:18 ` Peter Chen
2015-04-17 2:18 ` Peter Chen
2015-04-17 7:21 ` Roger Quadros
2015-04-17 7:21 ` Roger Quadros
2015-04-17 14:03 ` Alan Stern
2015-04-17 14:03 ` Alan Stern
2015-04-20 7:00 ` Roger Quadros
2015-04-20 7:00 ` Roger Quadros
2015-04-20 13:56 ` Alan Stern
2015-04-20 13:56 ` Alan Stern
2015-04-21 7:02 ` Roger Quadros [this message]
2015-04-21 7:02 ` Roger Quadros
2015-04-14 10:41 ` [RFC][PATCH v2 08/13] usb: otg: hub: Notify OTG fsm when A device sets b_hnp_enable Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-17 2:28 ` Peter Chen
2015-04-17 2:28 ` Peter Chen
2015-04-17 7:32 ` Roger Quadros
2015-04-17 7:32 ` Roger Quadros
2015-04-14 10:41 ` [RFC][PATCH v2 03/13] usb: otg-fsm: Prevent build warning "VDBG" redefined Roger Quadros
2015-04-14 10:41 ` Roger Quadros
[not found] ` <1429008120-5395-4-git-send-email-rogerq-l0cyMroinI0@public.gmane.org>
2015-04-16 11:41 ` Peter Chen
2015-04-16 11:41 ` Peter Chen
2015-04-16 11:59 ` Roger Quadros
2015-04-16 11:59 ` Roger Quadros
[not found] ` <552FA410.4030508-l0cyMroinI0@public.gmane.org>
2015-04-16 12:07 ` Peter Chen
2015-04-16 12:07 ` Peter Chen
2015-04-14 10:41 ` [RFC][PATCH v2 05/13] usb: otg: add OTG core Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-15 9:29 ` Paul Bolle
2015-04-15 13:24 ` Roger Quadros
2015-04-15 13:24 ` Roger Quadros
2015-04-16 12:02 ` Peter Chen
2015-04-16 12:02 ` Peter Chen
2015-04-16 13:04 ` Roger Quadros
2015-04-16 13:04 ` Roger Quadros
2015-04-14 10:41 ` [RFC][PATCH v2 07/13] usb: otg: Add dual-role device (DRD) support Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-14 10:41 ` [RFC][PATCH v2 09/13] usb: gadget: udc: adapt to OTG Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-14 10:41 ` [RFC][PATCH v2 10/13] udc-core: fix lock circular dependency on udc_lock Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-14 10:41 ` [RFC][PATCH v2 11/13] usb: add "dual-role" mode to dr_mode device tree helper Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-14 10:41 ` [RFC][PATCH v2 12/13] usb: dwc3: add dual-role support Roger Quadros
2015-04-14 10:41 ` Roger Quadros
2015-04-14 10:42 ` [RFC][PATCH v2 13/13] ARM: dts: dra7x-evm: Enable dual-role for usb1 Roger Quadros
2015-04-14 10:42 ` Roger Quadros
2015-04-20 3:05 ` [RFC][PATCH v2 00/13] USB: OTG/DRD Core functionality Peter Chen
2015-04-20 3:05 ` Peter Chen
2015-04-20 7:28 ` Roger Quadros
2015-04-20 7:28 ` Roger Quadros
[not found] ` <5534AA8C.1070400-l0cyMroinI0@public.gmane.org>
2015-04-21 6:04 ` Peter Chen
2015-04-21 6:04 ` Peter Chen
2015-04-21 7:34 ` Roger Quadros
2015-04-22 2:17 ` Peter Chen
2015-04-22 7:33 ` Roger Quadros
2015-04-22 7:33 ` Roger Quadros
2015-04-22 9:22 ` Peter Chen
2015-04-22 12:42 ` Roger Quadros
2015-04-23 1:52 ` Peter Chen
2015-04-23 6:35 ` Roger Quadros
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