linux-kernel - Re: [PATCH 21/33] clk: ux500: Add Device Tree support for the PRCC Kernel clock

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Message-ID: <20130912145651.GJ11227@lee--X1>
Date:	Thu, 12 Sep 2013 15:56:51 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>,
	Linus WALLEIJ <linus.walleij@...ricsson.com>,
	Mike Turquette <mturquette@...aro.org>,
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: Re: [PATCH 21/33] clk: ux500: Add Device Tree support for the PRCC
 Kernel clock

On Thu, 12 Sep 2013, Linus Walleij wrote:

> On Tue, Aug 27, 2013 at 10:23 AM, Lee Jones <lee.jones@...aro.org> wrote:
> > On Fri, 23 Aug 2013, Linus Walleij wrote:
> >> On Thu, Aug 22, 2013 at 11:21 AM, Lee Jones <lee.jones@...aro.org> wrote:
> 
> >> > 1. Duplicate each of the; clk_reg_prcmu_*(), clk_reg_prcc_pclk(),
> >> > clk_reg_prcc_kclk() calls into your proposed u8500_clk_init_dt(),
> >> > which, while keeping everything separate would be unrealistic.
> >>
> >> I think this is perfectly realistic.
> >>
> >> You're not going to duplicate each clk_register_clkdev(),
> >> which makes it way smaller than the original function,
> >> and since one of the function will be inside a
> >>
> >> #ifdef CONFIG_OF
> >> #endif
> >>
> >> After we switch the entire platform to DT-only it will be pretty
> >> obvious which big chunk of code that needs to go away, it's
> >> a clean cut.
> >>
> >> (Note: I know the #ifdef CONFIG_OF is not necessary anymore
> >> since we switched to multiplatform, but I intend that marker for
> >> humans, not machines.)
> >
> > This sounds gross. To duplicate; u8500_clk_init(), u8540_clk_init()
> > and u9540_clk_init() just for the sake of loading a few pointers into
> > an array for a small part of the development cycle sounds obscene.
> >
> > I genuinely think keeping the current patch in this series and then
> > removing the clk_register_clkdev() in the remove ATAG support series
> > is the best way to go.
> 
> So what I am worrying about is not only the looks of the code
> and what is beautiful or not may be something of an opinion
> anway.
> 
> What I worry about is leaving all the calls to clk_register_clkdev()
> in the DT boot path. Because that has the potential to hide a lot
> of bugs, as clk_get() from drivers that should've got named and
> probed randomly now will still find their clocks from their old
> device names, instead of using the <&ampersand> clocks from
> the device tree.
> 
> But if you still don't like this, let me cook a counter-patch so
> I can realized on my own how terribly wrong I am...

I'm going to yank all of the clk_register_clkdev() calls out
imminently anyway, so all those these hiding bugs will soon become
apparent in any case. Why don't I place my 'remove ATAGs' patch-set
on top of this one and then finally remove the clk_register_clkdev()s
and watch the carnage ensue?

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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