[PATCH v2] mx35: Fix boot ROM hang in internal boot mode

[u.kleine-koenig@pengutronix.de (Uwe Kleine-König)]

Hello Hans,

On Thu, Aug 12, 2010 at 01:37:21AM +0200, Hans J. Koch wrote:
> If a watchdog reset occurs after booting in internal boot mode, the i.MX35
> won't boot anymore. The boot ROM code seems to assume that some clocks are
> turned on (they are after a power-on reset). This patch turns on the
> necessary clocks.
> 
> Signed-off-by: Hans J. Koch <hjk@linutronix.de>
> ---
>  arch/arm/mach-mx3/clock-imx35.c |   20 ++++++++++++++++----
>  1 files changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm/mach-mx3/clock-imx35.c b/arch/arm/mach-mx3/clock-imx35.c
> index d3af0fd..e619bdc 100644
> --- a/arch/arm/mach-mx3/clock-imx35.c
> +++ b/arch/arm/mach-mx3/clock-imx35.c
> @@ -485,10 +485,10 @@ static struct clk_lookup lookups[] = {
>  
>  int __init mx35_clocks_init()
>  {
> -	unsigned int ll = 0;
> +	unsigned int cgr2 = 3 << 26, cgr3 = 0;
>  
>  #if defined(CONFIG_DEBUG_LL) && !defined(CONFIG_DEBUG_ICEDCC)
> -	ll = (3 << 16);
> +	cgr2 |= (3 << 16);
Please remove the parentheses here ...

>  #endif
>  
>  	clkdev_add_table(lookups, ARRAY_SIZE(lookups));
> @@ -499,8 +499,20 @@ int __init mx35_clocks_init()
>  	__raw_writel((3 << 18), CCM_BASE + CCM_CGR0);
>  	__raw_writel((3 << 2) | (3 << 4) | (3 << 6) | (3 << 8) | (3 << 16),
>  			CCM_BASE + CCM_CGR1);
> -	__raw_writel((3 << 26) | ll, CCM_BASE + CCM_CGR2);
> -	__raw_writel(0, CCM_BASE + CCM_CGR3);
> +
> +	/*
> +	 * Check if we came up in internal boot mode. If yes, we need some
> +	 * extra clocks turned on, otherwise the MX35 boot ROM code will
> +	 * hang after a watchdog reset.
> +	 */
> +	if (!(__raw_readl(CCM_BASE + CCM_RCSR) & (3 << 10))) {
> +		/* Additionally turn on UART0, SCC, and IIM clocks */
> +		cgr2 |= (3 << 16) | (3 << 4);
... and here ...
> +		cgr3 |= (3 << 2);
... and here.
> +	}
> +
> +	__raw_writel(cgr2, CCM_BASE + CCM_CGR2);
> +	__raw_writel(cgr3, CCM_BASE + CCM_CGR3);
Note that my question concerning the UART clock was less about UART1 vs
UART0 but more if the ROM really needs a UART clock.  And I prefer using
the name used in the manual, so UART1 please.

Thanks
Uwe

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Pengutronix e.K.                           | Uwe Kleine-K?nig            |
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