linux-kernel - Re: [PATCH v7 3/5] usb: dwc3: omap: Don't set POWERPRESENT

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Message-ID: <5731B6AD.9070108@ti.com>
Date:	Tue, 10 May 2016 13:23:41 +0300
From:	Roger Quadros <rogerq@...com>
To:	Felipe Balbi <balbi@...nel.org>
CC:	<tony@...mide.com>, <Joao.Pinto@...opsys.com>,
	<sergei.shtylyov@...entembedded.com>, <peter.chen@...escale.com>,
	<jun.li@...escale.com>, <grygorii.strashko@...com>,
	<yoshihiro.shimoda.uh@...esas.com>, <nsekhar@...com>,
	<b-liu@...com>, <linux-usb@...r.kernel.org>,
	<linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 3/5] usb: dwc3: omap: Don't set POWERPRESENT

On 10/05/16 13:04, Felipe Balbi wrote:
> 
> Hi,
> 
> Roger Quadros <rogerq@...com> writes:
>> On 10/05/16 12:54, Felipe Balbi wrote:
>>>
>>> Hi,
>>>
>>> Roger Quadros <rogerq@...com> writes:
>>>> TRM [1] recommends that POWERPRESENT bit must not be
>>>> set and left at it's default value of 0.
>>>>
>>>> [1] OMAP542x TRM - http://www.ti.com/lit/pdf/swpu249
>>>> Section 23.11.4.5.1 Mailbox VBUS/ID Management
>>>>
>>>> "Because PIPE powerpresent has a different meaning in host and in device mode,
>>>> and because of the redundancy with the UTMI signals, the controller ORes
>>>> together the appropriate PIPE and UTMI inputs to create its internal
>>>> VBUS status. For that reason, it is recommended to leave field
>>>> USBOTGSS_UTMI_OTG_STATUS[9] POWERPRESENT at its default value (=0), and only to
>>>> fill in the USB2 VBUS status fields in the same register."
>>>>
>>>> Signed-off-by: Roger Quadros <rogerq@...com>
>>>
>>> to make sure we avoid regressions, do you mind sharing on which
>>> platforms you tested this patch ?
>>>
>> I tested this on omap5-uevm and dra7-evm.
>> My am437x board stopped working so couldn't test on that one.
> 
> would you have a colleague or perhaps an automated test-farm which could
> run the test for you ? :-)
> 
> I can take the patch, no problem, but if there are any regressions don't
> blame me :-)
> 
Don't worry, blame is on the TRM then :).

cheers,
-roger