From: robert.jarzmik@free•fr (Robert Jarzmik)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 1/2] ARM: pxa: palm27x: fix udc device initialization
Date: Mon, 24 Dec 2012 16:34:28 +0100 [thread overview]
Message-ID: <87sj6vmpkr.fsf@free.fr> (raw)
In-Reply-To: <201212230424.16848.marex@denx.de> (Marek Vasut's message of "Sun, 23 Dec 2012 04:24:16 +0100")
Marek Vasut <marex@denx•de> writes:
> Dear Mike Dunn,
>
>> This patch fixes some bad behaviour from the usb gadget during machine
>> initialization by changing the management of the D+ pull-up gpio from the
>> gpio-vbus driver to the pxa27x-udc driver. Also, code that drives the
>> pull-up high is removed. (The gpio-vbus driver can optionally manage the
>> D+ line pull-up, but the pxa27x-udc driver does this itself.)
>>
>> Without this patch, the host senses the presence of the usb gadget during
>> machine initialization (when palm27x_udc_init() runs), at which point it
>> tries to enumerate the newly detected usb gadget. But because the
>> pxa27x-udc driver has not been initialized yet, there's no gadget driver
>> to respond to the host, and enumeration fails. Tested on my Palm Treo680.
> [...]
>
> I think it was the whole big idea to let gpio-vbus manage this kind of stuff.
> But it's been a while, Ccing Haojian to review these.
Actually gpio-vbus was designed to :
- detect and handle VBus
- and handle following D+ pullup if peripheral controller *can't*
But pxa27x_udc is a peripheral controller which does handle D+ pullup, and
expects to handle it by himself (ie. is not fully compatible with a D+ pullup
handling by gpio-vbus, one not working case being Mike's one).
So Mike's patch makes sense IMHO. He could have left the VBUS handling to
gpio-vbus and D+ to pxa27x_udc, or let pxa27x_udc handle both, that's up to you.
Acked-by: Robert Jarzmik <robert.jarzmik@free•fr>
--
Robert
next prev parent reply other threads:[~2012-12-24 15:34 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-22 18:27 [PATCH 0/2] ARM: pxa: palm27x: device initialization fixes Mike Dunn
2012-12-22 18:27 ` [PATCH 1/2] ARM: pxa: palm27x: fix udc device initialization Mike Dunn
2012-12-23 3:24 ` Marek Vasut
2012-12-24 15:34 ` Robert Jarzmik [this message]
2012-12-27 13:16 ` Mike Dunn
2012-12-22 18:27 ` [PATCH 2/2] ARM: pxa: palm27x: fix lcd " Mike Dunn
2012-12-23 3:24 ` Marek Vasut
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