Difference between ADMA and SDMA

Hello Ramappa,

ADMA - Advance DMA - see sections 25.4.5 DMA Modes in DRA7xx TRM

The ADMA is a DMA controller embedded in each eMMC controller. It can be seen as a small sequencer that fetches a descriptor line and executes the corresponding action. The base address of the descriptor table is stored in the MMCHS_ADMASAL register.
See a patch for adding ADMA support in OMAP - https://gitorious.org/linux-omap4-dev/omapboot/commit/d3bc987

The eMMC/SD/SDIOi host controller has direct access to the internal data. This feature is called advanced DMA (ADMA). It follows a specific algorithm (ADMA2) defined by an instruction in memory that starts at an address previously loaded in the MMCHS_ADMASAL register before any data command issued to the MMC card. Only 32-bit address spacing is supported by the controller for data storage.

SDMA - System DMA see chapter 16.1 System DMA in DRA7xx TRM.

The system direct memory access (DMA_SYSTEM) module, also called DMA4, performs high-performance data transfers between memories and peripheral devices without microprocessor unit (MPU) or digital signal processor (DSP) support during transfer. A DMA transfer is programmed through a logical DMA channel, which allows the transfer to be optimally tailored to the requirements of the application.

http://www.ti.com.cn/cn/lit/an/spra883/spra883.pdf

https://gitorious.org/omap-sw-develoment/linux-omap-dev/source/c9623de4fc2f8320fe94316b46171683be3b1d59:Documentation/DMA-API-HOWTO.txt

Best regards,

Yanko