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

IOn Sat, Sep 10, 2011 at 5:04 AM, Shawn Guo [off-list ref] wrote:

On Fri, Sep 09, 2011 at 10:29:49PM +0530, Santosh wrote:

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On Friday 09 September 2011 08:57 PM, Shawn Guo wrote:

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On Fri, Sep 09, 2011 at 07:41:08PM +0530, Shilimkar, Santosh wrote:

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On Fri, Sep 9, 2011 at 7:43 PM, Shawn Guo[off-list ref] ?wrote:

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On Fri, Sep 09, 2011 at 01:39:51PM +0530, Santosh wrote:

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On Friday 09 September 2011 01:34 PM, Shawn Guo wrote:

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Hi Santosh,

[...]

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#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 :)

Aha, no wonder that I read it wrongly. ?The parameter passing in r0
is here simply for confusing people.

No It's not. Same cod is used for CPUIDLE and we do have different
C-states than just OSWR. ON and INACTIVE makes use of it.

Also, IMO, lable "l2x_clean_inv" should be put after the "bne do_WFI".
Otherwise, my original statement (it seems l2x_clean_inv will be
called for case "2") stands correct :)

It's just a label. All L2 related code and checks for the valid state is
kept under that by purpose.

Regards
Santosh