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PSCI: Update comment on MMU disablement 

The MMU is not disabled in this path, update the comment to
reflect this. Also clarify that both paths call prepare_cpu_pwr_dwn(),
but the second path does stack cache maintenance.

Signed-off-by: Andrew F. Davis <afd@ti.com>
This commit is contained in:
Andrew F. Davis 2018-08-30 12:08:01 -05:00
parent f7a18268ad
commit c98db6c617
1 changed files with 6 additions and 9 deletions
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15
lib/psci/psci_common.c
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@ -948,21 +948,18 @@ void psci_do_pwrdown_sequence(unsigned int power_level)
/*
* With hardware-assisted coherency, the CPU drivers only initiate the
* power down sequence, without performing cache-maintenance operations
* in software. Data caches and MMU remain enabled both before and after
* this call.
* in software. Data caches enabled both before and after this call.
*/
prepare_cpu_pwr_dwn(power_level);
#else
/*
* Without hardware-assisted coherency, the CPU drivers disable data
* caches and MMU, then perform cache-maintenance operations in
* software.
* caches, then perform cache-maintenance operations in software.
*
* We ought to call prepare_cpu_pwr_dwn() to initiate power down
* sequence. We currently have data caches and MMU enabled, but the
* function will return with data caches and MMU disabled. We must
* ensure that the stack memory is flushed out to memory before we start
* popping from it again.
* This also calls prepare_cpu_pwr_dwn() to initiate power down
* sequence, but that function will return with data caches disabled.
* We must ensure that the stack memory is flushed out to memory before
* we start popping from it again.
*/
psci_do_pwrdown_cache_maintenance(power_level);
#endif