linux-kernel - Re: [PATCH v10 2/7] usb: mux: add generic code for dual role port mux

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 6 Jun 2016 15:35:25 +0800
From:	Lu Baolu <baolu.lu@...ux.intel.com>
To:	Peter Chen <hzpeterchen@...il.com>
Cc:	felipe.balbi@...ux.intel.com,
	Mathias Nyman <mathias.nyman@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Lee Jones <lee.jones@...aro.org>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, Roger Quadros <rogerq@...com>
Subject: Re: [PATCH v10 2/7] usb: mux: add generic code for dual role port mux

Hi Peter,

On 06/06/2016 03:02 PM, Peter Chen wrote:
>>>> > >> But this code is better co-work with OTG/Dual-role framework, we'd
>>>> > >> better have only interface that the user can know which role for the
>>>> > >> current port.
>>>> > >> OTG/Dual-role framework and portmux framework are not overlapped.
>>>> > >> The sysfs interface shouldn't be overlapped as well. Say, I have a port
>>>> > >> mux device and I have a driver for it. I am able to read the status of my
>>>> > >> port mux device through sysfs. This is not part of OTG/Dual-role as far
>>>> > >> as I can see.
>>>> > >>
>>> > > Then how the user wants to switch the role through the mux driver's
>>> > > sysfs or dual-role switch sysfs?
>>> > >
>> > 
>> > It depends. If you have an OTG/DRD capable controllers, you need to
>> > do this through OTG sysfs; otherwise you only need to switch the port.
>> > 
> The user may not know the detail, they will do role switch according to
> sysfs documentation. Yes, in your role switch case, only port mux is enough,
> but for others, it needs other operations.

So we need to make it clear in Documentation/ABI/testing/sysfs-bus-platform.

>
> I agree with Roger that the dual-role switch part in your code is better
> to use OTG framework to reduce redundancy.

I agree that we should use dual-role framework for role switch. Actually,
my code doesn't do this work. It only adds a generic framework for port
mux device and two mux device drivers used in Intel platform.

Best regards,
Lu Baolu