linux-kernel - Re: [PATCH 1/1] mfd: omap-usb-host: Fix USB device detection problems on OMAP4 Panda

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Date:	Mon, 2 Dec 2013 14:12:18 +0200
From:	Roger Quadros <rogerq@...com>
To:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
CC:	Michael Trimarchi <michael@...rulasolutions.com>,
	Felipe Balbi <balbi@...com>, <lee.jones@...aro.org>,
	<sameo@...ux.intel.com>, <tomi.valkeinen@...com>,
	Stefan Roese <sr@...x.de>, <ljkenny.mailinglists@...il.com>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	USB list <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] mfd: omap-usb-host: Fix USB device detection problems
 on OMAP4 Panda

On 12/02/2013 02:01 PM, Sebastian Andrzej Siewior wrote:
> - stable@...r.kernel.org since they probably don't care about this
>   unless the patch is merged.
> 
> On 12/02/2013 10:41 AM, Roger Quadros wrote:
>> Michael,
>>
>> On 11/29/2013 05:32 PM, Michael Trimarchi wrote:
>>> Hi Roger
>>>
>>> On Fri, Nov 29, 2013 at 2:01 PM, Roger Quadros <rogerq@...com> wrote:
>>>> With u-boot 2013.10, USB devices are sometimes not detected
>>>> on OMAP4 Panda. To make us independent of what bootloader does
>>>> with the USB Host module, we must RESET it to get it to a known
>>>> good state. This patch Soft RESETs the USB Host module.
>>>>
>>>
>>> Do you think that we need something similar of usb musb?
>>> I have seen the OTG_SYSCONFIG is touched in uboot and
>>> only readed in omap2430.c.
>>
>> I'm not sure about musb. Maybe Sebastian/Felipe have better idea.
>> In general I believe that all modules must be reset by the kernel.
>>
> 
> based on the code at the bottom it touches the first few register(s)
> sysconfig. Isn't hwmod actually doing this idle stuff and resting the
> device during boot?
> 

You are right. The musb hwmod data doesn't have the HWMOD_INIT_NO_RESET
flag, so hwmod should reset it during boot.

Maybe I too should just remove HWMOD_INIT_NO_RESET flag from the USB Host
hwmod data, then we don't need to change this driver at all.

Benoit, Tony any comments?

cheers,
-roger
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