linux-kernel - Re: [PATCH 1/5 v13] arm: omap: usb: ehci and ohci hwmod structures for omap4

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Date:	Mon, 10 Oct 2011 12:03:32 +0300
From:	Felipe Balbi <balbi@...com>
To:	"Munegowda, Keshava" <keshava_mgowda@...com>
Cc:	Paul Walmsley <paul@...an.com>, linux-usb@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
	balbi@...com, khilman@...com, b-cousson@...com, gadiyar@...com,
	sameo@...ux.intel.com, parthab@...ia.ti.com, tony@...mide.com,
	johnstul@...ibm.com, vishwanath.bs@...com
Subject: Re: [PATCH 1/5 v13] arm: omap: usb: ehci and ohci hwmod structures
 for omap4

Hi,

On Mon, Oct 10, 2011 at 02:22:23PM +0530, Munegowda, Keshava wrote:
> Hi paul and Felipe
> 
> Here is the highlights of the change in the design of  USB Host which
> we can do after kernel 3.2 release;
> 
> 1. separate the TLL changes  from UHH
> 2. The TLL is be a new platform driver in ./drivers/mfd
> 3. the TLL platform driver will export apis  for enable/disable clocks
> and settings.

TLL should control its clocks through pm_runtime APIs like anything
else. If you really must export APIs to be used by UHH, you need to have
an API so that you can claim/release a TLL channel and get/put for
increasing/decreasing PM counters.

I still think though, you should try to avoid exporting OMAP-specific
APIs all over the place. Ideally, we would be able to have some way of
saying that UHH and TLL are closely related... something like having the
ability to say e.g. two devices are sibblings of each other, so that we
could ask for a sibbling to wakeup/sleep depending if we need it or not.

Dunno, maybe I'm drifting here, but I don't think exposing OMAP-specific
APIs is wise.

-- 
balbi

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