linux-kernel - Re: [PATCH 2a/5] Remove unsafe clock values from omap1

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Message-Id: <201112011938.36706.jkrzyszt@tis.icnet.pl>
Date:	Thu, 1 Dec 2011 19:38:32 +0100
From:	Janusz Krzysztofik <jkrzyszt@....icnet.pl>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Paul Walmsley <paul@...an.com>, linux-omap@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2a/5] Remove unsafe clock values from omap1_defconfig

On Thursday 01 of December 2011 at 18:17:58, Tony Lindgren wrote:
> * Janusz Krzysztofik <jkrzyszt@....icnet.pl> [111201 01:20]:
[snip]
> > Perhaps 
> > we should rather think of reverting a few commits which caused all these 
> > problems if fixing them all during rc cycle seems not possible? I 
> > haven't bisected them yet, rather concentrated on providing fixes, but I 
> > can still try to do it, starting back from the original issue 
> > (http://www.spinics.net/lists/linux-omap/msg60052.html), if so decided.
> 
> We can't revert that because the SRAM init has been moved to later for
> map_io. 

Yes, I know that. What I don't know yet is what else should be reverted 
to fix the original issue other than applying  
e9b7086b80c4d9e354f4edc9e280ae85a60df408, which seems to introduce (or 
maybe 'exhibit' is a better word here) more bugs than it fixes.

> But if that patch changed the behaviour on your board, then that's
> the problem we should fix.
> 
> If you're now stuck at 60MHz rate, care to see if the following patch
> makes the kernel behave the same way as before for you?
[snip]
> 
> --- a/arch/arm/mach-omap1/clock_data.c
> +++ b/arch/arm/mach-omap1/clock_data.c
> @@ -927,7 +927,7 @@ int __init omap1_clk_init(void)
>  
>  void __init omap1_clk_late_init(void)
>  {
> -	if (ck_dpll1.rate >= OMAP1_DPLL1_SANE_VALUE)
> +	if (ck_dpll1.rate > OMAP1_DPLL1_SANE_VALUE)
>  		return;
>  
>  	/* Find the highest supported frequency and enable it */

This change really makes sense to me, however, knowing the initial 
(bootloader selected) clock rate my board boots at, which is 
unfortunately raw 12 MHz, I would be surprised if that helped.

Before e9b7086b80c4d9e354f4edc9e280ae85a60df408, 
omap1_select_table_rate() was returning the rate selected with .config 
because it was called early, with ck_dpll1_p->rate uninitialized. Now it 
is not, and returns nothing, resulting in 60 MHz default. Then, the only 
way I can see to correct the problem is something like patch 3/5, which 
you are justifiably affraid of of always switching to 216 MHz with 
omap1_defconfig.

Thanks,
Janusz
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