linux-kernel - Re: [RFC PATCH] clk: add extension API

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Message-ID: <20120531094616.GP5377@arwen.pp.htv.fi>
Date:	Thu, 31 May 2012 12:46:17 +0300
From:	Felipe Balbi <balbi@...com>
To:	Peter De Schrijver <pdeschrijver@...dia.com>
Cc:	Felipe Balbi <balbi@...com>, Stephen Boyd <sboyd@...eaurora.org>,
	Russell King <linux@....linux.org.uk>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Mike Turquette <mturquette@...com>,
	Paul Walmsley <paul@...an.com>, Kevin Hilman <khilman@...com>,
	Benoit Cousson <b-cousson@...com>
Subject: Re: [RFC PATCH] clk: add extension API

On Thu, May 31, 2012 at 12:43:01PM +0300, Peter De Schrijver wrote:
> > > > on Tegra:
> > > > 
> > > > device_reset(dev)
> > > > 	-> dev_pm_domain->reset()
> > > > 		-> tegra_periph_reset()
> > > > 
> > > 
> > > These methods are also needed internally by the powergating code.
> > 
> > so ? Just call them when you need...
> > 
> 
> the powergating code calls assert and deassert indepedently
> ie:
> 
> tegra_periph_reset_assert()
> 
> do stuff
> 
> tegra_periph_reset_assert()

I don't see the issue here. expose tegra_periph_reset() for the device
API only, internally you can do whatever you like. Call them
independently if you need.

> > > > on OMAP:
> > > > 
> > > > device_reset(dev)
> > > > 	-> dev_pm_domain->reset()
> > > > 		-> omap_hwmod_reset()
> > > > 
> > > > 
> > > > btw:
> > > > 
> > > > tegra_periph_reset(....)
> > > > {
> > > > 	tegra_periph_reset_assert(...);
> > > > 	udelay(2);
> > > > 	tegra_periph_reset_deassert(...);
> > > > }
> > > 
> > > which uses the clockframework currently.
> > 
> > no problems there. The point is that you already know which clock feed
> > into which device, so if you have a device-based API for device
> > soft-reset, you can figure out which exact clock to toggle, right ?
> 
> you have the struct clk, you could dive into that and grab clk_hw and call
> some function directly. But sounds quite horrible to me.

Well, that's just because struct device doesn't know about its own clock
providers, right ? Should that be patched too ?

Russell, as the orignal author of the clk API, what do you think ?

-- 
balbi

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