1. DSPGateway Architecture in Detail
Yoshiya Hirase
Nokia Research Center
Nokia Japan Co. Ltd.
© Nokia V1-Filename.ppt / yyyy-mm-dd / Initials

2. Agenda DSP Gateway Features Demonstration Using Nokia 770
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

3. DSP Gateway Features Open Source Software Simple interface for DSP
Integrated in Nokia 770 Internet Tablet
Simple interface for DSP
Efficient inter-processor communication (ARM <-> DSP)
Block data transfer via shared memory
DSP Task management
Dynamic Loader
Fault-tolerant mechanism
Power management
Simple interface for DSP
conventional Linux device files
Efficient inter-processor communication (ARM <-> DSP)
Minimum copy count for maximum throughput
Memory management
IPBUF: Inter-processor buffer mechanism (“Global”, “Private”, “System”)
mmap function
Multi-task environment for DSP applications
Fault-tolerant mechanism
Power management
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

4. History
2003/6: Released the DSP Gateway version 1.0 for OMAP1510 at SourceForge
2004/8: Supported OMAP1610/5912
2004/9: Merged into the Linux OMAP tree
2005/2H: Nokia 770 released with DSP Gateway
The latest DSP Gateway ver 3.3 supports OMAP 15XX (including 5910) and 16XX (including 1710 and 5912).
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

5. DSP Interface: Device Files
DSP task devices
interface to DSP task
DSP control device
miscellaneous DSP control
(e.g. DSP configuration)
DSP memory device
DSP memory access
DSP task watch device
for dynamic loader
DSP error detection device
error info delivery
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

6. Inter-Processor Communication
Communications via OMAP mailbox mechanism
OMAP
ARM
DSP
Mailbox registers
(16bit + 16bit)
interrupt
(16bit + 16bit)
interrupt
internal memory
IPBUF
IPBUF: Inter-communication buffer mechanism
memory
IPBUF
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

7. Inter-Processor Communication: IPBUF
Global IPBUF:
Used to transfer block data to/from DSP task
Prepared by the system and managed with alloc & free functions
Fixed block size, restricted block count
Private IPBUF:
A task can define an exclusive buffer, with arbitrary size
System IPBUF:
Used to transfer extra data between systems of ARM and DSP
ARM
DSP 1
task A
task A
(alloc)
(free) 1 2 3 4
Global IPBUF
Global IPBUF
ARM
DSP
task B Private IPBUF
task B
task B
Private IPBUF
ARM
DSP
System IPBUF
system
system
System IPBUF
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

8. Inter-Processor Communication:
Mailbox commands
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

9. Memory Mapping DSP internal memory External memory DARAM, SARAM SDRAM
Visible for ARM and DSP
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

10. Task Management: Dynamic Loader
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

11. Task Management: DSP Application Life Cycle
DSP Gateway
ARM
DSP
process 1
Linux application
Device driver
DSP kernel
DSP application
DSP task dynamically created
open()
open()
activate DSP task
complete
open() return
write()
write()
input data / control command
task running
write() return
output data
read()
read()
read() return
DSP task dynamically deleted
Example -dynamic task-
close()
close()
deactivate DSP task
complete
close() return
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

12. MP3 Pseudo program (ARM side)
int fd_mp3file, fd_dsp;
DATA buf[BUFSZ];
int Decode_MP3(void) {
// Open MP3 decoder device
fd_dsp = open(“/dev/dsptask/mp3dec”, O_RDWR);
// Initialize MP3 decoder
ioctl(fd, MP3_DECODE_INIT);
// Decode MP3 audio file
while (ReadMp3File(fd_mp3file, buf, BUFSZ) != EOF) {
// Send encoded data to MP3 decoder in DSP
write(fd_dsp, buf, BUFSZ); }
// Close MP3 decoder device
close(fd_dsp);
Issue TCTL command to DSP
Issue BKSND command to DSP
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

13. MP3 Pseudo program (DSP side)
Uns rcv_tctl(struct dsptask *task, Uns ctlcmd, Uns *ret, Uns arg) {
switch (ctlcmd) {
case MP3_DECODE_INIT:
InitIMDCT();
InitFilters();
break;
... }
Uns rcv_bksnd(struct dsptask *task, Uns bid, Uns cnt)
/* Decode received MP3 data */
Dequantize();
ReduceAlias();
IMDCT();
/* Send decoded PCM data to the Audio Device Driver */
Handle MP3_DECODE_INIT of TCTL command
Handle BKSND command
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

14. Nokia 770 Internet Tablet Features
Display
High-resolution (800x480) touch screen with up to 65,536 colors
Memory
Engine: DDR RAM 64MB
Memory: Flash 128MB (>64MB for user)
Memory card: 64MB RS-MMC (Reduced Size - MultiMediaCard)
Supported file formats
Audio: MP3, Real Audio, AAC, WAV, AMR
Image: JPEG, GIF, BMP, TIFF, PNG, Animated GIF format, SVG-tiny, ICO
Video: MPEG1, MPEG4, Real Video, H.263, 3GP
(RED items are decoded on DSP, BLUE items are routed through DSP)
Connectivity
WLAN: b/g
Bluetooth specification: 1.2
USB device mode for PC connectivity
RS-MMC
3.5 mm stereo audio out
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

15. Multimedia Software Architecture in Nokia 770
Linux
DSP/BIOS
Multimedia Player
GStreamer
Plugin #1 (Codec)
Plugin #2
Plugin #3
Codec #2
Codec #3
DSP Gateway
ARM
DSP
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

16. Future Work OMAP2420 support (including IVA support)
Driver Abstraction, and expansion for generic AMC (Asymmetric Multi-Core) processors
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

17. Demo: Play Media Files using DSP Gateway
System log message
Device status
Play sound or movie
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

18. References: Project page: Articles:
Articles:
森　英悟, 小林　俊裕, 高橋　清隆. “オープン・ソース・ソフトウェアDSPGatewayを用いたLinuxで使うOMAP DSP部のソフトウェア開発環境.” Interface: CQ Publishing, May 2004,
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

19. Thank you
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

20. Appendix: File manager Image
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

21. Appendix: Audio Player Image
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

22. Appendix: BKSND command in log
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

23. Appendix: TDEL command in log
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

24. Appendix: Task Status Transition
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

25. Appendix: Log message while playing MP3
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo

26. Appendix: Performance Evaluation Example
Memory mapping improves data transfer well
Data send latency (to DSP) by 44%-68%
Data receive latency (from DSP) by 27-55%
MPU bksnd := MPU sends a data blocks to DSP
MPUbkreq_DSPbksnd := MPU sends a block request to DSP -> DSP receives it & then sends the block back -> MPU receives the data block from DSP
Memory write/read := MPU writes/reads data on the mapped memory
© Nokia CELF_Nokia_Japan_v01.ppt / / NRC-Tokyo