[ECOS] FLASH woes continue

["Krishna Ganugapati" <krishnag at marakicorp dot com>]

My flash woes still continue..

1) I've started my board with ICACHE on and DCACHE disabled. - board works 
beautifully, for some reason whenever I execute the mcr instruction to 
enable the dcache (bit 2 in the cache control registers). However when I 
skip that one instruction it works beautifully well. I don't see this as a 
problem yet, the mmu is on and the dcache is off and this is a valid 
configuration

2) When the flash has to be initialized for the first time, the 
flash_hwr_init calls the flash_dev_query function, which then calls 
flash_query -> the function which probes the  flash for its configuration 
(num blocks, size of a block, sizeof of the write buffer and so on). Because 
we're probing the flash, this function needs to be copied into memory and 
then executed. This is the purpose of the  attribute 
section(".2ram.flash_query") causes the hal initialization to do the copy. 
Now because we're switching from executing in flash to executing in RAM, the 
flash_dev_query function executes the following:

HAL_CACHES_OFF(_d_, _i)

HAL_CACHES_OFF(_d_, _i_) does the following:

   HAL_DCACHE_IS_ENABLED(_d_)
   HAL_DCACHE_SYNC();
   HAL_DCACHE_INVALIDATE_ALL()
   HAL_DCACHE_DISABLE();
   HAL_ICACHE_INVALIDATE_ALL();

Now because I've disabled my dcache to start with, I replaced this macro 
with HAL_ICACHE_INVALIDATE_ALL()


3) Now the strangest thing happens - we successfully transfer to the 
flash_query function in RAM

00089ac <flash_query>:
   89ac: e3a02098  mov r2, #152 ; 0x98
   89b0: e3a01205  mov r1, #1342177280 ; 0x50000000
   89b4: e3a03bc3  mov r3, #199680 ; 0x30c00
   89b8: e1c120b0  strh r2, [r1]
   89bc: e3a02034  mov r2, #52 ; 0x34
   89c0: e2833d05  add r3, r3, #320 ; 0x140
   89c4: e2433001  sub r3, r3, #1 ; 0x1
   89c8: e3530000  cmp r3, #0 ; 0x0
   89cc: cafffffc  bgt 89c4 <flash_query+0x18>
   89d0: e3520000  cmp r2, #0 ; 0x0
   89d4: da000004  ble 89ec <flash_query+0x40>
   89d8: e0d130b2  ldrh r3, [r1], #2
   89dc: e2422001  sub r2, r2, #1 ; 0x1
   89e0: e3520000  cmp r2, #0 ; 0x0
   89e4: e4c03001  strb r3, [r0], #1
   89e8: cafffffa  bgt 89d8 <flash_query+0x2c>
   89ec: e3a030ff  mov r3, #255 ; 0xff
   89f0: e1c130b0  strh r3, [r1]
   89f4: e3a00000  mov r0, #0 ; 0x0
   89f8: e12fff1e  bx lr

The first three instructions or more never execute - so I never get  my mov 
r1, 0x50000000 executed. I'd thought that because prior to switching from 
flash to RAM, given that I've invalidated the cache, I'm assured that I will 
force the code to be loaded from memory but almost invariably I will never 
get 0x50000000 (which is the location of my FLASH into register r2 similarly 
I never get  0x30c00 loaded into r3 (this is the cnt value  to create a 20 
msec delay once the Flash_ReadQuery opcode is written to 0x50000000 to 
switch mode from ReadArray to ReadQuery - Following this everything is 
downhill, I never seem to be able to return the StrataFlash ReadQuery 
information..

Any thoughts on what I'm doing wrong here?

Krishna

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