EDMA on DM8148

Jay Gowdy81418

I have some memory to memory EDMA code which uses the EDMA3_LLD, v02.11.04.01 which works perfectly on my OMAP L138, but doesn't seem to work properly on the C6747 core of a DM8148.

The symptom is as follows: I reserve my channel, I set up the PaRAM to transfer from DDR to a buffer in L2, I start the transfer, and the PaRAM decrements down to 0, but the memory transfer just doesn't happen, i.e., the destination memory just doesn't change even though the PaRAM indicates that we have incremented through the transfers.

The transfer is very simple: a block of contiguous memory using ACNT=0xA00, BCNT=1, and CCNT=1. I set up my PaRAM like so and copy it into the right place using the LLD structures and routines,

paramSet    struct EDMA3_DRV_PaRAMRegs    {...} (Hex)    0x1081E110
    opt        unsigned int    0x0010E000 (Hex)0x1081E110
    srcAddr    unsigned int    0xB3D42380 (Hex)0x1081E114
    aCnt       unsigned short 0x0A00 (Hex)    0x1081E118
    bCnt       unsigned short 0x0001 (Hex)    0x1081E11A
    destAddr   unsigned int    0x1081E1A8 (Hex)0x1081E11C
    srcBIdx    short           0x0000 (Hex)    0x1081E120
    destBIdx   short           0x0000 (Hex)    0x1081E122
    linkAddr   unsigned short 0xFFFF (Hex)    0x1081E124
    bCntReload unsigned short 0x0000 (Hex)    0x1081E126
    srcCIdx    short           0x0000 (Hex)    0x1081E128
    destCIdx   short           0x0000 (Hex)    0x1081E12A
    cCnt       unsigned short 0x0001 (Hex)    0x1081E12C
    reserved   short           0x0000 (Hex)    0x1081E12E

After I copy it to the PaRAM, the appropriate PaRAM memory looks like,

8010E000
B3D42380
00010A00
1081E1A8
00000000
0000FFFF
00000000
00000001

and after I start the transfer, that PaRAM slot goes to

00000000
00000000
00000000
00000000
00000000
0000FFFF
00000000
00000000

which is what I associate with a "finished" transfer, but the destination memory in L2 (at 0x1081E114) is unchanged!

Is there anything obvious I have done wrong? Is there some other step I can take to debug this?

Thanks,

Jay

paramSet struct EDMA3_DRV_PaRAMRegs {...} (Hex) 0x1081E110

opt unsigned int 0x0010E000 (Hex) 0x1081E110

srcAddr unsigned int 0xB3D42380 (Hex) 0x1081E114

aCnt unsigned short 0x0A00 (Hex) 0x1081E118

bCnt unsigned short 0x0001 (Hex) 0x1081E11A

destAddr unsigned int 0x1081E1A8 (Hex) 0x1081E11C

srcBIdx short 0x0000 (Hex) 0x1081E120

destBIdx short 0x0000 (Hex) 0x1081E122

linkAddr unsigned short 0xFFFF (Hex) 0x1081E124

bCntReload unsigned short 0x0000 (Hex) 0x1081E126

srcCIdx short 0x0000 (Hex) 0x1081E128

destCIdx short 0x0000 (Hex) 0x1081E12A

cCnt unsigned short 0x0001 (Hex) 0x1081E12C

reserved short 0x0000 (Hex) 0x1081E12E

over 13 years ago

0 Radhesh Bhat over 13 years ago

Genius 4590 points

Hi Jay,

You need to provide physical address or L3 interconnect address of L2 RAM to EDMA i.e instead of 0x1080xxxx, use ox4080xxxxx.

Refer to the link : http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/716/p/216964/765000.aspx#765000

Regards

Radhesh

0 Jay Gowdy81418 over 13 years ago in reply to Radhesh Bhat

Intellectual 810 points

Thanks for the quick response. OK, that kind of makes sense (or at least it tells me why code that worked on the L138 doesn't work on the 8148).

A question on best practice: if I change my platform to put the L2 region at 0x408xxxx, will that cost anything in terms of memory access speed? I depend on the L2 SRAM being fast: by accessing it through the L3 memory map am I slowing those accesses down at all? Might it be better to have platform specific if statements in my memory transfer code that check to see if a source or destination is in L2 and add the appropriate amount?

Jay

0 Radhesh Bhat over 13 years ago in reply to Jay Gowdy81418

Genius 4590 points

Hi Jay,

I dont think there is any effect, because it is just the memory map of L2 being viewed by DSP and EDMA differently. DSP still need to access with the address 0x1080xxxx where as EDMA with 0x4080xxxx for accessing the same physical L2 memory.

Hope this helps.

Regards

Radhesh

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EDMA on DM8148