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Message-ID: <Pine.LNX.4.44L0.1303291607090.1467-100000@iolanthe.rowland.org>
Date: Fri, 29 Mar 2013 16:12:29 -0400 (EDT)
From: Alan Stern <stern@...land.harvard.edu>
To: Arnd Bergmann <arnd@...db.de>
cc: linux-usb@...r.kernel.org,
Manjunath Goudar <manjunath.goudar@...aro.org>,
<linux-arm-kernel@...ts.infradead.org>,
<linux-kernel@...r.kernel.org>, Greg KH <greg@...ah.com>,
David Brown <davidb@...eaurora.org>,
Daniel Walker <dwalker@...o99.com>,
Bryan Huntsman <bryanh@...eaurora.org>,
Brian Swetland <swetland@...gle.com>
Subject: Re: [PATCH v3 6/7] USB: EHCI: make ehci-msm a separate driver
On Thu, 28 Mar 2013, Arnd Bergmann wrote:
> From: Manjunath Goudar <manjunath.goudar@...aro.org>
>
> Separate the Qualcomm QSD/MSM on-chip host controller driver from
> ehci-hcd host code so that it can be built as a separate driver module.
> This work is part of enabling multi-platform kernels on ARM;
> however, note that other changes are still needed before Qualcomm QSD/MSM
> can be booted with a multi-platform kernel, which is not expected before
> 3.11.
>
> With the infrastructure added by Alan Stern in patch 3e0232039
> "USB: EHCI: prepare to make ehci-hcd a library module", we can
> avoid this problem by turning a bus glue into a separate
> module, as we do here for the msm bus glue.
This patch is good. However the ehci-msm driver itself is not. While
checking through the code, I was struck by the fact that it never calls
usb_add_hcd() or usb_remove_hcd(). Obviously the driver cannot work
properly.
In addition, it stores the PHY pointer in a global variable.
(ehci-atmel does much the same thing for its clocks.) This means the
driver cannot be used on a system having more than one EHCI controller.
Maybe this doesn't matter, though.
Maybe somebody would like to fix and test it...
Alan Stern
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