[PATCH 2/4] mx25: properly initialize clocks

[Baruch Siach]

Hi Uwe,

On Mon, Jul 05, 2010 at 09:08:26AM +0200, Uwe Kleine-König wrote:
> On Mon, Jan 25, 2010 at 12:58:20PM +0200, Baruch Siach wrote:
> > This patch disables all unnecessary clock in mx25_clocks_init() to make a clean
> > start, the same as is being done for the rest of the i.MX chips.
> > 
> > This patch was tested on i.MX25 PDK.
> > 
> > Signed-off-by: Baruch Siach <baruch at tkos.co.il>
> > ---
> >  arch/arm/mach-mx25/clock.c |    8 ++++++++
> >  1 files changed, 8 insertions(+), 0 deletions(-)
> > 
> > diff --git a/arch/arm/mach-mx25/clock.c b/arch/arm/mach-mx25/clock.c
> > index abd303b..08aaa38 100644
> > --- a/arch/arm/mach-mx25/clock.c
> > +++ b/arch/arm/mach-mx25/clock.c
> > @@ -218,6 +218,14 @@ int __init mx25_clocks_init(void)
> >  	for (i = 0; i < ARRAY_SIZE(lookups); i++)
> >  		clkdev_add(&lookups[i]);
> >  
> > +	/* Turn off all clocks except the ones we need to survive, namely:
> > +	 * EMI, GPIO1-3 (CCM_CGCR1[18:16]), GPT1, IOMUXC (CCM_CGCR1[27]), IIM,
> > +	 * SCC
> > +	 */
> > +	__raw_writel((1 << 19), CRM_BASE + CCM_CGCR0);
> > +	__raw_writel((0xf << 16) | (3 << 26), CRM_BASE + CCM_CGCR1);
> > +	__raw_writel((1 << 5), CRM_BASE + CCM_CGCR2);
> > +
> I would prefer having symbolic names for the constants used here because
> otherwise comment and code tend to diverge.
> 
> And I didn't check the manuals, but some other imx clock code (e.g.
> arch/arm/mach-mx3/clock-imx35.c) pay attention to CONFIG_DEBUG_LL being
> defined.  Is this needed here, too?

The mx35 clock code enables UART1 (i.e. ttymxc0) when CONFIG_DEBUG_LL is 
defined. I used the settings above with CONFIG_DEBUG_LL and earlyprintk to 
diagnose early boot crashes on mx25 without problem. So I'm not sure this is 
necessary.

Besides, CONFIG_DEBUG_LL builds on mx25 (and mx1) are broken in the mainline 
kernel ):. See http://thread.gmane.org/gmane.linux.ports.arm.kernel/75691.

baruch

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