From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
To: David Brownell <david-b@pacbell.net>
Cc: avorontsov@ru.mvista.com,
Andrew Morton <akpm@linux-foundation.org>,
greg@kroah.com, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
leoli@freescale.com, timur@freescale.com
Subject: Re: [PATCH 3/3] USB: driver for Freescale QUICC Engine USB Host Controller
Date: Wed, 24 Sep 2008 23:17:55 +0400 [thread overview]
Message-ID: <48DA9263.5060103@ru.mvista.com> (raw)
In-Reply-To: <200809241159.04427.david-b@pacbell.net>
Hello.
David Brownell wrote:
>>>> ... then the root hub emulation is completely pointless.
>>>It isn't. We always should emulate the root hub. The root hub
>>>is part and parcel of any USB Host. Even the one-port one.
>> Hm, maybe that's what USB core thinks (because UHCI/OHCI/EHCI all
>>have it) but e.g. MUSB doesn't have the root hub registers...
> Only the OHCI registers have bit positions matching what the USB
> spec says for hub status bits.
Oh, didn't know that.
> Everything else, including musb_hdrc, has the relevant status encoded in other bits.
Yes, but I thought that if there are no multiple ports, having the hub is
just pointless.
>>I looked at the core and figured that USB core seems to use the root hub
>>interface for port PM, etc. and expects it to bee present, so it seems
>>unavoidable indeed... :-/
> Or more fundamentally: for enumeration. "Unavoidable" is correct. ;)
Not sure what you mean here but I guess having a root hub alows an uniform
model of controlling the ports... anyway, USB specifies that it must be
present in the host.
WBR, Sergei
next prev parent reply other threads:[~2008-09-24 19:17 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-18 15:16 [PATCH 0/3] Patches to support QE USB Host Controller Anton Vorontsov
2008-09-18 15:17 ` [PATCH 1/3] gpiolib: make gpio_to_chip() public Anton Vorontsov
2008-09-18 15:17 ` [PATCH 2/3] powerpc/qe: new call to revert a gpio to a dedicated function Anton Vorontsov
2008-09-18 15:17 ` [PATCH 3/3] USB: driver for Freescale QUICC Engine USB Host Controller Anton Vorontsov
2008-09-19 23:23 ` Andrew Morton
2008-09-23 18:31 ` Anton Vorontsov
2008-09-23 18:32 ` [PATCH 1/2] USB: Protect hcd.h from multiple inclusions Anton Vorontsov
2008-09-23 18:32 ` [PATCH 2/2] USB: driver for Freescale QUICC Engine USB Host Controller Anton Vorontsov
2008-09-23 21:32 ` [PATCH 3/3] " Sergei Shtylyov
2008-09-23 21:35 ` Sergei Shtylyov
2008-09-23 22:57 ` Anton Vorontsov
2008-09-24 10:24 ` Sergei Shtylyov
2008-09-24 10:48 ` Sergei Shtylyov
2008-09-24 18:59 ` David Brownell
2008-09-24 19:17 ` Sergei Shtylyov [this message]
-- strict thread matches above, loose matches on Subject: below --
2008-08-08 16:17 [PATCH 0/3] Patches to support QE " Anton Vorontsov
2008-08-08 16:18 ` [PATCH 3/3] USB: driver for Freescale QUICC Engine " Anton Vorontsov
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