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Date: Fri, 14 Apr 2006 14:54:36 -0500
To: Paul Mackerras <paulus@samba.org>
Subject: Re: 7447A strange problem with MSR:POW (WAS: can't boot 2.6.17-rc1)
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From: Olof Johansson <olof@lixom.net>
Cc: Becky Bruce <Becky.Bruce@freescale.com>,
	Michael Schmitz <schmitz@zirkon.biophys.uni-duesseldorf.de>,
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Hi,

On Fri, Apr 14, 2006 at 12:07:23PM -0700, Paul Mackerras wrote:
> Becky Bruce writes:
> 
> > Actually, I think the problem is that the code linux is using to turn  
> > on nap mode is not guaranteed to put the processor in nap mode by the  
> > time the blr in ppc6xx_idle occurs.
> 
> Thanks, Becky.
> 
> This patch fixes it for me.  Comments, anyone?

The bf mnemonics had me scratching my head a while, it's not listed as
a simplified mnemonic in the 64-bit PEM. Two questions below.

>  _GLOBAL(power_save_6xx_restore)
> +	tophys(r11, r1)		/* Make the idle task do a blr */
> +	lwz	r9,_LINK(r11)
> +	stw	r9,_NIP(r11)
>  	mfspr	r11,SPRN_HID0
> -	rlwinm.	r11,r11,0,10,8	/* Clear NAP & copy NAP bit !state to cr1 EQ */
> -	cror	4*cr1+eq,4*cr0+eq,4*cr0+eq
> +	rlwinm	r11,r11,0,10,8	/* Clear NAP */
>  BEGIN_FTR_SECTION
>  	rlwinm	r11,r11,0,9,7	/* Clear DOZE */
>  END_FTR_SECTION_IFSET(CPU_FTR_CAN_DOZE)
>  	mtspr	SPRN_HID0, r11
>  
>  #ifdef DEBUG
> -	beq	cr1,1f
> +	bf	9,1f

Where is cr0 set now -- you took the dot off of rlwinm?

>  	lis	r11,(nap_return_count-KERNELBASE)@ha
>  	lwz	r9,nap_return_count@l(r11)
>  	addi	r9,r9,1
>  	stw	r9,nap_return_count@l(r11)
>  1:
>  #endif
> -	
> +
> +#ifdef CONFIG_SMP
>  	rlwinm	r9,r1,0,0,18
>  	tophys(r9,r9)
>  	lwz	r11,TI_CPU(r9)
>  	slwi	r11,r11,2
> +#else
> +	li	r11,0
> +#endif
>  	/* Todo make sure all these are in the same page
> -	 * and load r22 (@ha part + CPU offset) only once
> +	 * and load r11 (@ha part + CPU offset) only once
>  	 */
>  BEGIN_FTR_SECTION
> -	beq	cr1,1f
> +	bf	9,1f

Same comment as above w.r.t. cr0?



-Olof