UM0851 datasheet(162/245 Pages) STMICROELECTRONICS

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Accelerator engine device drivers

UM0851

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Doc ID 16604 Rev 2

else if (pid > 0)

// parent

{

jpegread();

wait(0);

}

else

// failed to fork

{

printf("Cant create child\n");

exit(1);

}

6.1.3

JPEG device driver performance

The JPEG driver performance has been measured in the following environment:

●

Hardware: ARM926EJS (333 MHz), SPEAr600, SPEAr300, SPEar310 and SPEAr320

evaluation boards.

●

Kernel: linux-2.6.27

Configuration options

6.1.4

References

●

SPEAr JPEG Driver "drivers/char/spr_jpeg_syn.c, drivers/char/spr_jpeg_syn.h and

include/linux/spr_jpeg_syn_usr.h"

6.2

General purpose DMA (DMAC) driver

All SPEAr MPUs are equipped with a general purpose DMA Controller which provides

several DMA channels that can be used to off load the CPU from some of the memory

copying tasks. This section describes the details of the DMAC driver.

6.2.1

Hardware overview

Direct memory access (DMA) allows certain subsystems within the SPEAr MPU to access

system memory for reading and/or writing independently of the CPU and to transfer data

without subjecting the CPU to a heavy overhead.

Table 43.

JPEG driver configuration options

Configuration option

Comment

CONFIG_SPEAR_JPEG_SYN

This option enables the SPEAr JPEG driver.

CONFIG_SPEAR_JPEG_SYN_DEBUG

This option enables debug prints in the JPEG

driver.

CONFIG_SPEAR_DMAC_PL080

This option must be selected for JPEG

operations. This will enable the DMA driver.

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