Rockbox

  • Status Closed
  • Percent Complete
    100%
  • Task Type Patches
  • Category Drivers
  • Assigned To No-one
  • Operating System Another
  • Severity Low
  • Priority Very Low
  • Reported Version Release 3.4
  • Due in Version Undecided
  • Due Date Undecided
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Attached to Project: Rockbox
Opened by FlynDice - 2010-03-15
Last edited by funman - 2010-04-13

FS#11106 - Add test & clean cache coherency functions to mmu-arm.S

This patch adds some cache coherency functions to mmu-arm.S that only apply to the arm926ej-s core in the newer as3525v2 sansas. You can ask these cores to test the caches to see if they are dirty and use a loop to clean until there are no more dirty lines left in the cache. See page 2-23 of the ARM926EJ-S TRM for more info. There are versions of these functions present in the OF.

Closed by  funman
2010-04-13 15:05
Reason for closing:  Accepted
Additional comments about closing:  

r25628

The at91sam9260, dm320, and tcc780x CPUs also are arm926-ejs

Aren’t these operations generic to ARMv5? The #ifdef should probably just test #if ARM_ARCH >= 5 ?

Are they related to the operations ARMv6 has?

(/me hasn’t looked at mmu-armv6.S, not at the mentioned datasheet)

My understanding was that these just applied to the 926ej-s and 1026ej-s but I have not really researched that aspect. I tested the test_clean_DCache() function by replacing the clean_dcache_range() in pcm-as3525.c. It appears to work just fine but I cannot claim it to work any better yet than what is used now. It is much easier to use though.

Attached patch replace invalidate_dcache and clean_dcache (alias cpucache_flush) for ARMv5

According to linux this works on all armv5tej
According to wikipedia all armv5 are TE, the J bit should have no influence

The ARM Architecture Reference Manual Issue E (v5T) doesn’t mention those functions.
The ARM Architecture Reference Manual Issue I (v6) does, but they are marked as optional.

Perhaps we should add a capability defined for CPUs which support it (like arm926ejs)

Add specific define for arm926ej-s

Correct functions for as3525(v1) : the cache is 2x smaller than arm920t used by gigabeatf/x and mini2440, so there is 1 less index bit
Tested on Clipv1

The arm920/arm922 caches are 64-way and the arm926 cache is 4-way so the index format obviously can’t work on arm926ej-s (it misses some cache sets)

Just needs testing on gigabeat F/X and/or mini2440

Sync to SVN

Use .rept gnu asm macro for indexed cleaning/invalidating

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