AM35x-OMAP35x-PSP 03.00.00.05 Feature Performance Guide

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About This Manual
This document provides an overview and performance data for each of the device drivers which are part of the Linux PSP package supporting AM3517,OMAP35x and AM/DM37x Socs. Note that only a subset of these platforms may have actually been tested and verified in the package you are using. Please refer to the release notes provided with the package for information on which platforms have actually been verified.

If You Need Assistance
For further information or to report any problems, contact http://community.ti.com/ or http://support.ti.com/

Trademarks
OMAPTM is trademark of Texas Instruments Incorporated. All other trademarks are the property of the respective owner.

= PSP Linux Drivers =

This section provides brief overview of the device drivers supported in the Linux PSP release based on Linux OMAP git tree at http://git.kernel.org/?p=linux/kernel/git/tmlind/linux-omap-2.6.git

Note: The constraints may vary across product releases. Please refer to the Release Notes accompanying the release for an updated list of constraints.

OMAP Linux PSP details

 * 1) Supports for OMAP35x(ES3.1),AM/DM37x(ES1.0) Socs (on OMAP3EVM Rev.G) and AM3517 Soc on AM3517EVM. Only sanity testing has been carried out on older OMAP35x EVM with ES2.1 Si
 * 2) Built with Linux kernel version 2.6.32/PM.
 * 3) Compiled with code sourcery tool chain version arm-2009-q1-203.
 * 4) Supports U-Boot version 2009.11
 * 5) Supports boot from MMC and NAND flash.
 * 6) Ships with sample root file system, ramdisk, pre-built u-boot, uImage binaries, sample applications and documentation.

Boot modes supported
Green colored box in the table below means that the particular boot mode is supported on the device.

Note: These are supported boot modes in PSP software, the actual hardware may support many more boot modes than shown here. Please refer to hardware documentation for list of all supported boot modes.

Frequency Used for Measurements
The ARM MPU frequency can be specified through "mpurate" bootargs(refer to UserGuide for further details). For purpose of throughput measurement published in this document the following frequency table is assumed.

Drivers not supported

 * 1) Power Management (cpufreq, cpuidle) on AM3517

Driver DMA usage
= ALSA SoC Audio Driver =

This section provides details on ALSA SoC audio driver along with throughput and CPU load numbers.

Introduction
OMAP35x, AM/DM37x, AM3517 audio driver complies to the ALSA SoC framework.

ASoC framework provides better audio support for embedded SoC processors and portable audio codecs. It splits an embedded audio system into three components:
 * Codec driver: The codec driver is generic and hardware independent code that configures the audio codec to provide audio capture and playback. It should contain no code that is specific to the target platform or machine.
 * Platform driver: The platform driver can be divided into audio DMA and SoC Digital Audio Interface (DAI) configuration and control. The platform driver only targets the SoC CPU and must have no board specific code.
 * Machine driver: The ASoC machine (or board) driver is the code that glues together the platform and codec drivers. It can contain codec and platform specific code. It registers the audio subsystem with the kernel as a platform device.

Following architecture diagram shows all the components and the interactions among them:

Driver Features
The driver supports the following features:


 * 1) Supports AIC23 audio codec (on AM3517 only) and TPS65950 audio codec (on OMAP35x, AM/DM37x only) in ALSA SoC framework.
 * 2) Multiple sample rates support (8KHz, 16KHz, 22.05KHz, 32KHz, 44.1KHz, 48KHz, 64KHz, 88.2KHz and 96KHz - AM3517; 8 KHz, 11.025 KHz, 12 KHz, 16 KHz, 22.05 KHz, 24 KHz, 32 KHz, 44.1 KHz and 48 KHz - OMAP35x) for both capture and playback.
 * 3) Supports audio in stereo mode.
 * 4) Supports simultaneous playback and record (full-duplex mode).
 * 5) Start, stop, pause and resume feature.
 * 6) Supports mixer interface for audio codecs.
 * 7) Supports MMAP mode for both playback and capture.

Features Not Supported

 * 1) OSS based applications, which use ALSA-OSS emulation layer, are not supported.
 * 2) Formats such as TDM, Left and Right Justified are currently not supported.
 * 3) Synthesizer and midi interfaces are not supported.

Constraints

 * 1) By default, codec is configured in master mode and McBSP is used as slave. Testing of the audio sub-system is done in this configuration only.
 * 2) Sampling frequencies for playback and capture streams should be same.
 * 3) The audio driver does not allow opening the same stream (playback/capture) multiple times.

Supported System Calls
Refer ALSA project - the C library reference for API calls.

Supported IOCTLs
NA

Performance and Benchmarks
The performance numbers were captured using the following:


 * Word length in bits = 16
 * Number of channels per sample = 2
 * Power Management = Disabled

The performance numbers are same for on each of OMAP35x, AM/DM37x and AM3517 platforms. Commands used to capture the same are:


 * aplay -c 2 -f S16_LE -r < > <> :- Normal mode
 * arecord -c 2 -f S16_LE -r < > <> :- Normal mode
 * aplay -c 2 -f S16_LE -r < > -M <> :- MMAP mode
 * arecord -c 2 -f S16_LE -r < > -M <> :- MMAP mode

= Ethernet Driver =

This section provides details on Ethernet driver along with throughput and CPU load numbers.

Introduction
The Ethernet driver supports the Linux netdev interface.

Driver Features
The driver supports the following features:


 * 1) 10/100 Mbps mode of operation.
 * 2) Auto negotiation.
 * 3) Support for multicast and broadcast frames.
 * 4) Promiscuous mode of operation.
 * 5) Full duplex and half duplex mode of operation.
 * 6) Linux NAPI support

Features Not Supported
NA

Constraints
NA

Supported System Calls
Supports the socket and related system calls in accordance with Linux architecture.

OMAP35x,AM/DM37x,AM3517
The performance numbers were captured using the iperf tool. Usage details are mentioned below:


 * On the DUT iperf is invoked in client mode : "-c &lt;server ip&gt; -w &lt;window size&gt; -d -t60"
 * On PC Host invoke iperf in the server mode : "-s"  - window size default of 212KB
 * The transfers are measured over a duration of 60Secs
 * Cross cable is used to measure performance.
 * Speed is set to 100Mbps
 * Power Management disabled for measurement

The performance numbers were captured using the iperf tool. Usage details are mentioned below:


 * On the PC Host iperf is invoked in client mode : "-c &lt;server ip&gt; -w &lt;window size&gt; -d -b 100M -t60"
 * On DUT invoke iperf in the server mode : "-s -u -w 256k "
 * The transfers are measured over a duration of 60Secs
 * Cross cable is used to measure performance.
 * Speed is set to 100Mbps
 * Power Management disabled for measurement

= Video Display Driver =

This section describes the Video Display driver architecture, driver features and performance numbers (throughput and CPU load).

Introduction
Video Display driver is based on two different frameworks, V4L2 and FBDEV.



Driver Features

 * 1) Supports interfaces LCD, DVI and TV out
 * 2) Supports TV display interface at NTSC and PAL resolutions
 * 3) Supports YUV, UYVU, RGB565, RGB24P and RGB24 unpacked on video planes, in addition ARGB on video2 plane.
 * 4) Supports RGB565, ARGB, RGBA, RGB24 packed and unpacked on graphics plane
 * 5) Video planes controlled through V4L2 user interface whereas Graphic plane controlled through FBDEV user interface
 * 6) Supports setting up of OSD window destinations (TV or LCD) through sysfs
 * 7) Supports mmapped (driver allocated) and user buffer exchange mechanism in V4L2 driver and only mmapped (driver allocated) buffers in FBDEV driver
 * 8) Supports rotation - 0, 90, 180 and 270 degrees
 * 9) Supports scaling from 1/4x to 8x on video pipelines
 * 10) Supports Wait for Vsync and Panning feature under FBDEV
 * 11) Supports Alpha blending, both global alpha and pixel alpha
 * 12) Supports Source and Destination color keying through V4L2 ioctls
 * 13) Supports Modular build

Driver Features - OMAP35x, AM/DM37x

 * 1) Supports LCD display interface at VGA resolution (480*640)
 * 2) Supports Generic Brightness class driver

Driver Features - AM3517

 * 1) Supports LCD display interface at resolution (480*272)

Features Not Supported

 * 1) RGB888 rotation is not supported
 * 2) RFBI interface is not supported
 * 3) DSI/SDI serial interface is not supported
 * 4) Dynamic Changing of modes (NTSC/PAL) for TV out not supported
 * 5) Linking feature not supported on video pipelines
 * 6) Mirroring is not supported

Constraints

 * 1) Incorrect configuration of parameters results in Sync Lost
 * 2) Minimum 3 Buffers are required for streaming in V4L2
 * 3) PAL resolution can be set maximum to 720 x 574 instead of 720 x 576 because of hardware limitation
 * 4) Upscaling and downscaling with images more that 720x574 resolution is not supported because of dss functional clock frequency limitation
 * 5) Since LCD_ENVDD (GPIO153) is required to power up TSC controller, the default state would be on irrespective of default selected output.

Supported System Calls
open, close, read, mmap, munmap and ioctl

Performance Benchmarks
Setup Details -


 * TV - Hitachi LCD TV (NTSC/PAL)
 * DVI Monitor - Dell Monitor (720P/480P) without rotation
 * CPU Idle - Disabled
 * Tool Used for measurement - LFTB
 * Description: Panned for 1000 frames with maximum resolution supported by panel without any memory operation.
 * Commands Used -
 * ./fbdev_display_tests -r -l -g -w -h

OMAP35x,AM/DM37x,AM3517

 * Description: Streaming for 1000 frames with maximum resolution supported by panel without any memory operation.
 * Commands Used -
 * 

= Video Capture Driver = This section describes the Video Capture driver architecture, driver features and performance numbers (throughput and CPU load).

Introduction
Current V4L2 sub-system is supporting 3 different frameworks, V4L2-Int, SoC-Cam and Sub-Dev. Out of these, 2 has already become legacy framework and all future driver must use Sub-Dev framework.

Although from user application point of view the interface will remain the same, driver follows standard V4L2 interface.

OMAP35x, AM/DM37x
OMAP35x and AM/DM37x Video Capture driver is based on V4L2-Int framework.



AM3517
AM3517 Video Capture driver is based on V4L2 Sub_device framework.



Driver Features

 * 1) Supports one software channel and a corresponding device node (/dev/video0) for capture module
 * 2) Supports mmapped (driver allocated) and user buffer exchange mechanism
 * 3) Supports dynamic switching among input interfaces with some necessary restrictions wherever applicable
 * 4) Supports NTSC and PAL standard on Composite and S-Video interfaces
 * 5) Supports 8-bit BT.656 capture in UYVY and YUYV interleaved formats
 * 6) Supports standard V4L2 IOCTLs to get/set various control parameters like brightness, contrast and saturation
 * 7) Supports Modular build

Driver Features - OMAP35x, AM/DM37x

 * 1) Supports both Multi-Media Daughter Card and on-board Video Decoder (NOTE:Both are mutual exclusive to each other)

Features Not Supported

 * 1) Cropping and scaling operations and their corresponding V4L2 IOCTLs
 * 2) Raw capture (capture through sensor interface)

Features Not Supported - OMAP35x, AM/DM37x

 * 1) On-the-fly previewer interface is not supported
 * 2) All internal processing block, H3A, Histogram, black level compensation, etc.. are not supported
 * 3) CSI serial interface is not supported
 * 4) On-the-fly resizing operation

Constraints

 * 1) Dynamic switching of resolution and dynamic switching of interfaces is not supported when streaming is on
 * 2) Driver buffer addresses and pitch must be aligned to 32 byte boundary

Constraints - OMAP35x, AM/DM37x

 * 1) In case of USERPTR with VM_IO, the buffer size must be 4096 byte aligned

Constraints - AM3517

 * 1) Greenish color is seen due to Hardware know issue, Application must implement Reverse A-Law table (Please refer to the sample application available with release for reference)

Supported System Calls
open, close, mmap, munmap and ioctl

Performance Benchmarks
Setup Details -


 * DVD Player - Sony (DVP-NS51P)
 * TV - Hitachi LCD TV (NTSC/PAL)
 * CPU Idle - Disabled
 * Tool Used for measurement - saUserPtrLoopback.c
 * Description: Loopback from capture device node to display device for 1000 frames with maximum resolution supported by panel without any memory operation.
 * Commands Used -
 * ./saUserPtrLoopback -i -r 0

OMAP35x,AM/DM37x,AM3517
= Video Resizer Driver (Only for OMAP35x and AM/DM37x) =

This section describes the Video Resizer driver architecture, driver features and performance numbers (throughput and CPU load).

Introduction
OMAP35x Video Resizer driver is simple character driver using V4L2-buffer layer for buffer management.

Driver Features

 * 1) Resizes input frame stored in RAM and stores output frame in RAM
 * 2) Supports resizing from 1/4x to 4x
 * 3) Supports independent horizontal &amp; vertical resizing
 * 4) Supports YUV422 packed and color separate data
 * 5) Supports driver allocated and user provided buffers including IOMEM
 * 6) Supports Modular build

Features Not Supported

 * 1) On-the-fly mode of operation

Constraints

 * 1) All input,ouput addresses and pitch must be 32 bytes aligned
 * 2) Output image size cannot be more than 2047x2047
 * 3) Output width must be even
 * 4) Output width must be 16 byte aligned for vertical resizing
 * 5) The horizontal start pixel must be within range 0-15 for color interleaved and 0-31 for color separate data

Supported System Calls
open, close, mmap, munmap and ioctl

Performance Benchmarks
Setup Details -


 * CPU Idle - Disabled
 * Tool Used for measurement - LFTB
 * Description: Calculate time required for single resize operation and for CPU load issue resize operation in contiguous loop with queuing buffer for each resize.

OMAP35x and AM/DM37x
= NAND Driver =

This section describes the NAND flash driver architecture, driver features and performance numbers (throughput and CPU load).

Introduction
The NAND flash driver is implemented as both - block driver and character driver, compliant with the standard MTD driver. It supports various NAND Flash chips (see drivers/mtd/nand/nand_ids.h file.) The NAND driver creates the device nodes for user space access (/dev/mtdblock0, /dev/mtdblock1, /dev/mtd0,/dev/mtd1 and so on). This release has been tested with Micron NAND device on the OMAP3EVM/AM3517EVM

This figure illustrates the stack diagram of NAND flash driver in Linux.

Driver Features
The driver supports the following features:


 * 1) JFFS2 file system
 * 2) Supports Read/Write, Erase operations
 * 3) Bad Block Management
 * 4) Polled mode of transfer
 * 5) SLC NAND
 * 6) NAND Flash divided into 5 partitions
 * 7) 512KB partition for X-loader
 * 8) 1920 KB (Read Only) partition for U-Boot
 * 9) 128 KB (Read Only) for environment variables
 * 10) 5 MB (Read/Write) partition for Linux
 * 11) Remainder for file system and others (Read/Write)

Features Not Supported
None

Constraints
None

Supported System Calls
Supports the system call support proivided by MTD interface viz. open, close, read, write, ioctl

Performance Benchmarks
The performance numbers are captured using the following:


 * 1) NAND PART Number: Micron MT29F4G08AAC
 * 2) CPU Power Management disabled.
 * 3) File System = JFFS2
 * 4) NAND partition was mounted with async option.

= MMC/SD Driver =

This section provides details on MMC/SD driver along with throughput and CPU load numbers.

Introduction
The MMC controller provides an interface to external MMC cards that follow the MMC specification v4.0. The MMC driver is implemented as a block driver. Block device nodes(such as /dev/mmcblockp1, /dev/mmcblockp2) are created for user space access.

Driver Features
The driver supports the following features:


 * 1) MMC/SD native protocol command/response set
 * 2) Single/multiple block data transfers
 * 3) Linux file system and generic MMC layer abstract details of block devices (MMC)
 * 4) High-speed (SDv1.1) and High Capacity (SDv2.0) cards
 * 5) Support for 1/4 bit modes
 * 6) Support for card detect and Write protect features
 * 7) DMA mode for data transfer operations
 * 8) SDIO functionality (tested with marvell 8686 wlan card)

Features Not Supported

 * 1) Support for 8-bit mode of operation.
 * 2) SPI mode of operation

Constraints

 * 1) MMC/SD cards should not be removed when the mount operation is in progress. If done so, data integrity cannot be guaranteed.

Supported System Calls
open,close,read,write

Supported IOCTLs
None

Performance and Benchmarks
Important

The performance numbers can be severely affected if the media is mounted in sync mode.

Performance Measurement using EXT2 file system
The performance numbers were captured using the following:


 * SD Card (Sandisk Extreme III,SDHC,Class 6, 4GB)
 * CPU Power Management: Disabled
 * File System: ext2
 * Partition was mounted with async option

Performance Measurement using VFAT file system
The performance numbers were captured using the following:


 * SD Card (Sandisk Extreme III,SDHC,Class 6, 4GB)
 * CPU Power Management: Disabled
 * File System: vfat
 * Partition was mounted with async option

= Real Time Clock (RTC) Driver (Only for AM3517) =

This section provides details on RTC (S35390A) driver along with throughput and CPU load numbers.

Introduction
AM3517 EVM supports external RTC chip S35390A over I2C1.



Driver Features
The driver supports the following features:


 * 1) Supports IOCTLs to set/get the time/date value
 * 2) Driver can be built as a loadable module and inserted dynamically.

Features Not Supported

 * Interrupt based Wake-up and respective IOCTL's

Constraints
None

Supported System Calls
open, close, write, read</tt>

Performance and Benchmarks
None

= USB Driver =

This section describes the USB (EHCI and MUSB) driver architecture, features supported/not supported, constraints and performance numbers.

OMAP35x
OMAP3EVM (Rev &lt; E) has EHCI port on Mistral Daughter Card (MDC) while on OMAP3EVM (Rev &gt;= E) EHCI port is on main board itself.

AM/DM37x
EHCI port is on main board of OMAP3EVM (Rev G) which is used for testing AM/DM37x.

AM3517
AM3517EVM has one EHCI port on base board and another EHCI port on UI card. EHCI port on UI card would work only if LCD is not enabled as LCD and UI card EHCI port share some IO pins.

Driver Features
The driver supports the following features


 * 1) Hub Class
 * 2) Mass Storage Class (MSC)
 * 3) Human Interface Class (HID) (through a high speed hub)
 * 4) USB Video Class (UVC)
 * 5) USB Audio Class (UAC)

Features Not Supported
All other classes not mentioned in the "Supported Features" section.

OMAP35x
The MUSB driver is implemented on top of Mentor OTG IP version 1.4 which supports all the speeds (High, Full and Low).MUSB uses inventra DMA for all the transfers. OMAP3EVM uses ISP1504 external USB PHY on EVM-1 (Rev < E) and ISP1507 on EVM-2 (Rev >= E).

AM/DM37x
The MUSB driver is implemented on top of Mentor OTG IP version 2.0 which supports all the speeds (High, Full and Low).MUSB uses inventra DMA for all the transfers.

AM3517
The MUSB driver is implemented on top of Mentor OTG IP version 1.8 which supports all the speeds (High, Full and Low).MUSB uses CPPI4.1 DMA for all the transfers. AM3517 has USB PHY inside IP itself.

Driver Features
The driver supports the following features

Host Mode


 * 1) Hub Class
 * 2) Human Interface Class (HID)
 * 3) Mass Storage Class (MSC)
 * 4) USB Video Class (UVC)
 * 5) USB Audio Class (UAC)

Gadget mode


 * 1) Mass Storage Class (MSC)
 * 2) USB Networking - RNDIS/CDC

OTG mode


 * 1) Session Request Protocol (SRP)
 * 2) Host Negotiation Protocol (HNP)

Features Not Supported

 * 1) All other classes not mentioned in the "Supported Features" section.

Constraint

 * 1) There is a limitation in the power that is supplied by the charge pump of the ISP1504 PHY on OMAP3EVM-1 (&lt;=Rev-E). If you notice VBUSERR messages in the system console, then connect a self powered USB hub and then attach the device to the hub
 * 2) OMAP3EVM-2 (&gt;=Rev-E) can support upto 500mA power and thus self powered hub is not required.VBUS must be re-enabled after disconnect and reconnect of the MSC device while the MUSB image is built in OTG mode

Description
This figure illustrates the stack diagram of the system with USB Mass Storage Class driver

Driver Features
The driver supports the following feature


 * 1) DMA mode
 * 2) PIO mode

Features Not Supported
None

Constraint
None

Supported System Calls
Supports the Linux file system related system calls.

Supported IOCTLS
None

Performance Benchmarks
Important

For Mass-storage applications, the performance numbers can be severely affected if the media is mounted in sync mode. Hot plug scripts in the filesystem mount removable media in sync mode to ensure data integrity. For performance sensitive applications, umount the auto-mounted filesystem and re-mount in async mode.

The numbers for USB MSC were obtained using internal benchmarking tool.

USB MSC Host mode DMA Ext2 File System Performance
The performance numbers are captured using the following.


 * 1) Hard disk: Toshiba 80GB DISK DRIVE
 * 2) File format: ext2
 * 3) CPU Idle state: Disabled
 * 4) Driver operating mode: DMA
 * 5) Total transfer size = 100MB
 * 6) System DMA on all Rx channels (Workaround for known Inventra DMA lockup issue on OMAP35x): Disabled

USB MSC Host mode DMA VFAT File System Performance
The performance numbers are captured using the following.


 * 1) Hard disk: Toshiba 80GB DISK DRIVE
 * 2) File format: vfat
 * 3) CPU Idle state: Disabled
 * 4) Driver operating mode: DMA
 * 5) Total transfer size = 100MB
 * 6) System DMA on all Rx channels (Workaround for known Inventra DMA lockup issue on OMAP35x): Disabled

Description
This figure illustrates the stack diagram of the system with USB File Storage Gadget driver

Driver Features
The driver supports the following feature


 * 1) DMA mode
 * 2) PIO mode

Features Not Supported
None

Constraint
None

Supported System Calls
NA

Supported IOCTLS
NA

Performance Benchmarks
The performance numbers are captured using the following.


 * 1) Storage media: Toshiba 80 GB HDD connected to EHCI port
 * 2) File format: vfat on Windows XP
 * 3) CPU Idle state: off
 * 4) Driver operating mode: DMA
 * 5) System DMA on all Rx channels (Workaround for known Inventra DMA lockup issue on OMAP35x): Disabled

Description
The CDC RNDIS gadget driver that is used to send standard Ethernet frames using USB. The driver will create an Ethernet device by the name usb0.

Driver Features
The driver supports the following feature


 * 1) DMA mode
 * 2) PIO mode

Features Not Supported
None

Constraint
None

Supported System Calls
MUSB port would come up as network device interface and would supports all network subsystem related system calls in accordance with Linux architecture.

Supported IOCTLS
None

Performance Benchmarks
Note: iperf execution failed on AM/DM37x so numbers are not provided for them.

OMAP35x, AM/DM37x, AM3517
The performance numbers were captured using the iperf tool. Usage details are mentioned below:


 * On the PC Host iperf is invoked in the server mode : "-s"
 * On DUT invoke iperf in client mode : "-c &lt;server ip&gt; -w &lt;window size&gt; -d -t60"
 * The transfers are measured over a duration of 60Secs
 * Power Management disabled for measurement
 * Linux2.4 host machine has been used for CDC.

Description
The event sub system creates /dev/input/event* devices when USB HID devices are connected. Dell USB Keyboard and Microsoft USB mouse has been used for testing HID class.

Driver Features
The driver supports the following feature


 * 1) DMA mode
 * 2) PIO mode

Features Not Supported
None

Constraint
None

Supported System Calls
NA

Supported IOCTLS
NA

Performance Benchmarks
NA

Description
USB camera, speaker and mike uses isochronous transfers. USB Video Class (UVC) is used by most of the USB cameras to capture image.Microsoft USB headset, Logitech Pro-9000 and Creative Live USB cameras have been used for testing purpose.

Driver Features
The driver supports the following feature


 * 1) DMA mode
 * 2) PIO mode
 * 3) Supports high bandwidth isochronous transfer used by some of the USB cameras

Features Not Supported
None

Constraint

 * 1) Default musb FIFO table has only one endpoint with 4KB FIFO size to support high bandwidth isochronous transfer. Thus we need to modify the table to support more then one USB cameras requiring high bandwidth interface.

Supported System Calls
NA

Supported IOCTLS
NA

Performance Benchmarks
NA

Description
MUSB controller on OMAP35x/DM37x and AM35x EVM supports USB On The Go (OTG). OTG protocol enables runtime role switch between USB host and device. This is achieved using Session Request Protocol (SRP) and Host Negotiation Protocol (HNP).

Driver Features
The driver supports the following feature


 * 1) Both HNP and SRP

Constraint
None

=Power Management=

Introduction
OMAP35x, AM/DM37x devices provides a rich set of power management features. The features include clock control at module level, multiple power and voltage domains etc.

This section provides provides an overview of power management features supported and steps to enable these features in the kernel configuration. It also provides the typical power consumption observed for different scenarios.

NOTE

The AM3505 and AM3517 devices provide a simple power management scheme. There is only one power domain and only one operating frequency. This section, therefore, doesn't contain any measurement for these devices.

cpuidle
When idle loop is executed, kernel is not doing any useful 'work'. This is an opportunity to save power. The  framework helps in saving power during the idle state.

cpufreq
CPU is not loaded evenly during execution. This provides an opportunity to save power by adjusting/scaling voltage and frequency based on the current cpu load.

SmartReflex
SmartReflex is a power-management technique for controlling the operating voltage of a device to reduce its active power consumption. It helps in achieving optimal performance/power trade-off for all devices across the technology process spectrum and across temperature variations.

Features
The features supported in this release are:
 * Dynamic Tick (NO_HZ) framework.
 * Static selection of VDD1 OPP via bootarg -.
 * On OMAP35x devices, VDD1 OPP can be scaled (if silicon supports) upto 720MHz.
 * The capability of device to run at 720MHz is detected at run-time. If the device doesn't support 720MHz, and the bootarg  is set, next (lower) OPP is selected.
 * On AM/DM37x devices, VDD1 OPP can be scaled upto 800MHz.
 * When OPP1 is selected for VDD1, the VDD2 is set at OPP2.
 * Supports the suspend-resume capability
 * The cpuidle framework with MPU and Core transition to retention (RET) and OFF states.
 * The menu governor is supported.
 * Basic implementation for cpufreq.
 * Support SmartReflex with automatic (hardware-controlled) mode of operation.
 * Wakeup from keypad and touchscreen.

Features not supported

 * 1) Allow drivers and applications to limit the idle state that can be entered.
 * 2) Support for SmartReflex with manual (software-controlled) mode of operation.

Constraints

 * 1) Only basic implementation of cpufreq is supported.
 * 2) Some of the drivers do not leverage the power-saving features supported by the silicon. They need to enable/ disable corresponding clocks via   and   only when the clocks are really needed.

Power Measurements
The measurements in this section were done on OMAP3EVM (Rev G) with NI-USB 6251 and TI power consumption tool.


 * The measurements were done at identified system state for period of ~60 secs.
 * Voltage and current values for VDD1 and VDD2 are measured across jumpers J6 and J5 respectively.
 * SmartReflex is enabled in the kernel configuration; but is not activated at runtime.

Specific scenarios associated with the measurement are indicated in the details below.

NOTE

A ramdisk image based on minimal busybox configuration is used during these measurements. Actual numbers may vary with daemons and processes running (configured in the filesystem).

At each OPP
This section indicates the voltages measured for VDD1 and VDD2 at various OPPs (selected via bootarg - ). The measurements were done with the  created using.

AM/DM37x
NOTE

Refer to the device specific TRM for OPP definitions.

Against specific scenarios
This section indicates the VDD1 measurements against identified scenarios.

The measurements were done with bootarg  set to 720MHz for OMAP35x devices and 800MHz for AM/DM37x devices.

Scenario 1

 * 1) Build uImage with power management disabled and dynamic tick disabled.
 * 2) Boot the EVM with this uImage and ramdisk.

Scenario 2

 * 1) Build uImage with power management disabled but dynamic tick enabled.
 * 2) Boot the EVM with this uImage and ramdisk

Scenario 3

 * 1) Build uImage with power management, power management debug, DebugFS and dynamic tick enabled; but no cpuidle.
 * 2) Boot the EVM with this uImage and ramdisk.
 * 3) After boot-up, mount debugfs
 * 4) Execute these commands:
 * 5) Wait for 30 secs and start the measurement.
 * 1) Execute these commands:
 * 2) Wait for 30 secs and start the measurement.
 * 1) Wait for 30 secs and start the measurement.

Scenario 4

 * 1) Build uImage with power management, power management debug, DebugFS, dynamic tick and cpuidle enabled.
 * 2) Boot the EVM with this uImage and ramdisk.
 * 3) After boot-up, mount debugfs
 * 4) Execute these commands:
 * 5) Wait for 30 secs and start the measurement.
 * 1) Execute these commands:
 * 2) Wait for 30 secs and start the measurement.
 * 1) Wait for 30 secs and start the measurement.

Scenario 5

 * 1) Build uImage with power management, power management debug, DebugFS, dynamic tick and cpuidle enabled.
 * 2) Boot the EVM with this uImage and ramdisk.
 * 3) After boot-up, mount debugfs
 * 4) Execute these commands:
 * 5) Wait for 30 secs and start the measurement.
 * 1) Execute these commands:
 * 2) Wait for 30 secs and start the measurement.
 * 1) Wait for 30 secs and start the measurement.
 * 1) Wait for 30 secs and start the measurement.

NOTE 1

For scenarios 1 and 2 the voltage doesn't scale to required levels as power management is disabled.

NOTE 2

For scenarios 3, 4 and 5 the voltage scales to required levels as power management is enabled.

= CAN(HECC) Driver =

This section provides details on CAN(HECC) driver.

Introduction
The CAN (HECC) driver supports the Linux netdev interface. CAN driver supports TX and RX mailbox priority feature ensuring in-order packet processing at various bit rates.

Driver Features
The driver supports the following features:


 * 1) SocketCAN networking framework
 * 2) Linux NAPI support for Rx operations
 * 3) Local loopback of sent frames (IFF_ECHO)
 * 4) Standard CAN bus bit-rates namely 10K, 20K, 50K, 100K, 125K, 250K, 500K &amp; 1M

Features Not Supported

 * 1) ID filtering / Acceptance masks - since Linux infrastructure does not support this the driver cannot provide the feature

Constraints
NA

Supported System Calls
Supports the  and related system calls in accordance with Linux architecture. Refer to  under   folder

Performance and Benchmarks
NA

Category :OMAP35x