Hi everybody,
I am wondering if it would be possible to release a version of volumio that has the video disabled? The goal is to drastically limit the power needed to run Volumio on a Udoo board, but other boards will be equally happy with this, as power requirements go from about a big 3 watts to a very limited 700 mW.
How?
Disable the FPU/GPU, and/or set the maximum clockrate on the ARM CPU`s.
Taken from Freescale itself. An example:
( cache.freescale.com/files/32bit/ … AN4509.pdf )
3.3.1
Use Case 1—MP3 Audio Playback
The use case procedure is as follows:
- MP3 (MPEG-1 audio layer 3) decoding is done by ARM.
- Audio playback is run through SSI (serial synchronous interface).
- The stream 128 Kbps_44 kHz_s_mp3.mp3 is taken from the SD (secure digital) card.
Table 5. MP3 Audio Playback Measurement Results when this use case is applied on the i.MX 6Dual/6Quad processor.
Supply Domain Voltage (V)
VDDARM_IN 1.42 39.05 27.5
VDDSOC_IN 1.42 122.12 86
VDDHIGH_IN 2.78 128.71 46.3
Total Power (without DDR3 I/O + Memories) 289.88
DDR3 I/O + Memories 1.5 69.75 46.51
Total Power 359.632
With Video:
3.4 Video Playback Use Cases
3.4.1 Use Case 1—H.264 Video Playback, 1080p on HDMI LCD
A video from the movie Avatar was taken for this use case. This use case has the following features:
• The video source is H.264, 1080p resolution, 30 FPS, 3.6 Mbps bitrate
• The audio source is AAC 44.1 Kbps stereo.
• VDOA module is used to reduce DDR bus load.
• The display is 1080p resolution using HDMI.
The video/audio stream is loaded from the SD card into the DDR (double data rate) memory and then
demuxed by Cortex-A9. The demuxed video signal is decoded by the VPU. It is then taken by IPU and
displayed on the LCD display (through HDMI) with a refresh rate of 60 Hz. In parallel, the demuxed
audio signal is decoded using Cortex-A9 and is played back through the SSI.
Table 6. 1080P Video Playback Measurement Results when this use case is applied on the i.MX 6Dual/6Quad processor.
Supply Domain Voltage (V)
VDDARM_IN 1.42 58.36 41.1
VDDSOC_IN 1.42 609.75 429.4
VDDHIGH_IN 2.78 199.05 71.6
Total Power (without DDR3 I/O + Memories) 867.16
DDR3 I/O + Memories 1.5 442.95
304.5
295.31
202.72
Total Power 1310.113
Now without having support to clock the Arm core etc, running a full Dhrystone Benchmark:
3.5 Dhrystone Benchmark
3.5.1 Use Case 1—Quad Core Dhrystone Benchmark
In this use case, Dhrystone test is performed by all four cores. The ARM processor runs the test in a loop
at a frequency of 1 GHz.
Supply Domain Voltage (V)
VDDARM_IN 1.42 2272 1600
VDDSOC_IN 1.42 451.56 318
VDDHIGH_IN 2.78 140.95 50.7
Total Power (without DDR3 I/O + Memories) 2864.51
DDR3 I/O + Memories 1.5 40.2 26.81
1 The ODT settings are—120 Ω for the memory and for the i.MX 6Dual6/Quad DDR I/O
the ODT is disabled.
Total Power 2904.712
As I am measuring a power requirement of about 3, 3 Watts when running Volumio, I take it:
- The GPU/VPU is still powered
- The ARM cores are running fully on.
It would be very nice to be able to choose between a few options:
- Disable Video when no video is needed at all.
- enable lower CPU clock settings. This doesnt have to be dynamic, one might want to choose between full, medium or half etc.
All this might result in power requirements going down almost 90%.
Would this be considered a lot andimportant enough to develop? I sincerely hope so! It would give an edge over the competition, and sound quality might also enhance further, as the lower the power, the better it might sound. the same goes for the Kernel settings, they make a whole lot of difference. In my humble opinion, Orion is by far the best, but it could be a lot better and greener!
Marco
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