[PATCH 14/25] OMAP4: PM: Add CPUX OFF mode support

[Santosh]

On Friday 09 September 2011 08:57 PM, Shawn Guo wrote:
> On Fri, Sep 09, 2011 at 07:41:08PM +0530, Shilimkar, Santosh wrote:
>> On Fri, Sep 9, 2011 at 7:43 PM, Shawn Guo<shawn.guo at freescale.com>  wrote:
>>> On Fri, Sep 09, 2011 at 01:39:51PM +0530, Santosh wrote:
>>>> On Friday 09 September 2011 01:34 PM, Shawn Guo wrote:
>>>>> Hi Santosh,

[...]

>> #ifdef CONFIG_CACHE_L2X0
>> 	/*
>> 	 * Clean and invalidate the L2 cache.
>> 	 * Common cache-l2x0.c functions can't be used here since it
>> 	 * uses spinlocks. We are out of coherency here with data cache
>> 	 * disabled. The spinlock implementation uses exclusive load/store
>> 	 * instruction which can fail without data cache being enabled.
>> 	 * OMAP4 hardware doesn't support exclusive monitor which can
>> 	 * overcome exclusive access issue. Because of this, CPU can
>> 	 * lead to deadlock.
>> 	 */
>> l2x_clean_inv:
>> 	bl	omap4_get_sar_ram_base
>> 	mov	r8, r0
>> 	mrc	p15, 0, r5, c0, c0, 5		@ Read MPIDR
>> 	ands	r5, r5, #0x0f
>> 	ldreq	r0, [r8, #L2X0_SAVE_OFFSET0]
>> 	ldrne	r0, [r8, #L2X0_SAVE_OFFSET1]
>> 	cmp	r0, #3
>> 	bne	do_WFI
>
> It looks like you are bypassing L2 clean and invalidate for cases
> "1" and "2" here.  But I really do not understand how you get r0
> back here.
>
The value which is passed in R0 is also stored in scratch patch memory
and retrieved using L2X0_SAVE_OFFSET0.
Simple :)

Regards
Santosh