[PATCH 14/25] OMAP4: PM: Add CPUX OFF mode support
Kevin Hilman
khilman at ti.com
Fri Sep 9 14:34:48 EDT 2011
Santosh <santosh.shilimkar at ti.com> writes:
> 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 :)
Sounds like some in-code documentation needs to be added to make this a
bit more understandable.
Thanks,
Kevin
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