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From: Lu Baolu <baolu.lu@linux.intel.com>
To: Jun Li <jun.li@nxp.com>, Roger Quadros <rogerq@ti.com>,
	Peter Chen <hzpeterchen@gmail.com>
Cc: "felipe.balbi@linux.intel.com" <felipe.balbi@linux.intel.com>,
	Mathias Nyman <mathias.nyman@intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Lee Jones <lee.jones@linaro.org>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>,
	"linux-usb@vger.kernel.org" <linux-usb@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v10 2/7] usb: mux: add generic code for dual role port mux
Date: Tue, 7 Jun 2016 17:53:31 +0800	[thread overview]
Message-ID: <5756999B.9020809@linux.intel.com> (raw)
In-Reply-To: <AM4PR04MB2130809FDDC36F2C7F8C0F25895D0@AM4PR04MB2130.eurprd04.prod.outlook.com>

Hi,

On 06/07/2016 11:03 AM, Jun Li wrote:
> Hi Roger
>
>>  
>> For Mux devices implementing dual-role, the mux device driver _must_ use
>> OTG/dual-role core API so that a common ABI is presented to user space for
>> OTG/dual-role.
> That's the only point we have concern, do dual role switch through
> OTG/dual-role core, not do it by itself.
>
>> I haven't yet looked at the mux framework but if we take care of the above
>> point then we are not introducing any redundancy.
>>
> Roger, actually this is my worry on OTG core: those dual role switch
> users just tends to do it simply by itself(straightforward and easy),
> not through the OTG core(some complicated in first look),

I'm sorry, but I'm really confused.

Why do we need to drop "straightforward and easy", but have to run
an *unnecessary* OTG state machine? Don't you think that will (1) add
*unnecessary* software complexity; (2) increase *unnecessary* memory
footprint; and (3) increase the debugging efforts?

> this is just an example for us to convince people to select a better
> way:)

Sure. Let's take my case for an example.

My system has a third-party port mux, which is not part any USB controllers.
Also, my system doesn't have any DRD capable devices. I need a
"straightforward and easy" driver for it. Otherwise, the system could not be
waken up from system suspend.

But you said I must run an unnecessary OTG state machine, even thought it
has nothing to do with my system, only because the two sides of my port
mux device is a host and peripheral controller.

Why?

Best regards,
Lu Baolu

  parent reply	other threads:[~2016-06-07  9:53 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-02  1:37 [PATCH v10 0/7] usb: add support for Intel dual role port mux Lu Baolu
2016-06-02  1:37 ` [PATCH v10 1/7] regulator: fixed: add support for ACPI interface Lu Baolu
2016-06-08  4:42   ` Greg Kroah-Hartman
2016-06-08 13:43     ` Mark Brown
2016-06-08 15:46       ` Greg Kroah-Hartman
2016-06-09  2:43     ` Lu Baolu
2016-06-02  1:37 ` [PATCH v10 2/7] usb: mux: add generic code for dual role port mux Lu Baolu
2016-06-03  7:41   ` Peter Chen
2016-06-03  8:16     ` Heikki Krogerus
2016-06-03  9:20       ` Peter Chen
2016-06-03 16:06     ` Lu Baolu
2016-06-04  2:28       ` Peter Chen
2016-06-05  6:55         ` Lu Baolu
2016-06-05  8:33           ` Jun Li
2016-06-05  8:46             ` Lu Baolu
2016-06-06  1:08               ` Jun Li
2016-06-06  2:30                 ` Lu Baolu
2016-06-06  2:05               ` Peter Chen
2016-06-06  2:45                 ` Lu Baolu
2016-06-06  6:48                   ` Peter Chen
2016-06-06  1:25           ` Peter Chen
2016-06-06  3:04             ` Lu Baolu
2016-06-06  7:02               ` Roger Quadros
2016-06-07  3:03                 ` Jun Li
2016-06-07  6:27                   ` Lu Baolu
2016-06-07  6:34                     ` Jun Li
2016-06-07  9:27                       ` Lu Baolu
2016-06-07 12:49                         ` Roger Quadros
2016-06-07  9:53                   ` Lu Baolu [this message]
2016-06-07 12:58                     ` Roger Quadros
2016-06-07 13:04                       ` Felipe Balbi
2016-06-07 14:02                         ` Roger Quadros
2016-06-07 15:05                           ` Felipe Balbi
2016-06-08  3:04                             ` Jun Li
     [not found]                               ` <5757A8CB.90402@linux.intel.com>
2016-06-08  6:20                                 ` Jun Li
2016-06-08  6:25                             ` Peter Chen
2016-06-08  7:58                             ` Roger Quadros
2016-06-06  7:02               ` Peter Chen
2016-06-06  7:35                 ` Lu Baolu
2016-06-02  1:37 ` [PATCH v10 3/7] usb: mux: add driver for Intel gpio controlled " Lu Baolu
2016-06-02  1:37 ` [PATCH v10 4/7] usb: mux: add driver for Intel drcfg " Lu Baolu
2016-06-02  1:37 ` [PATCH v10 5/7] mfd: intel_vuport: Add Intel virtual USB port MFD Driver Lu Baolu
2016-06-02  1:37 ` [PATCH v10 6/7] usb: pci-quirks: add Intel USB drcfg mux device Lu Baolu
2016-06-08  4:45   ` Greg Kroah-Hartman
2016-06-08  7:56     ` Lu Baolu
2016-06-08 15:45       ` Greg Kroah-Hartman
2016-06-09  2:39         ` Lu Baolu
2016-06-16  0:27           ` Lu Baolu
2016-06-18  0:58             ` Greg Kroah-Hartman
2016-06-19  9:52               ` Lu Baolu
2016-06-02  1:37 ` [PATCH v10 7/7] MAINTAINERS: add maintainer entry for Intel USB dual role mux drivers Lu Baolu

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