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  1. Ventana Thermal Information
    1. Gateworks System Controller (GSC)
    2. IMX6 SoC
      1. Linux Kernel Support
      2. U-Boot Support
    3. Vivante GPU thermal management

Ventana Thermal Information

See also:

Gateworks System Controller (GSC)

The Gateworks System Controller has a temperature sensor that measures board temperature as well as a fan controller on some models.

For more information:

IMX6 SoC

The IMX6 System On Chip has an internal die temperature sensor.

There are several temperature grades of IMX6 SoC's that are used across various Gateworks products:

Linux Kernel Support

The Linux IMX6 cpufreq cooling driver (drivers/thermal/imx_thermal.c) provides several functions:

There is a Linux sysfs API for accessing this information:

Notes:

U-Boot Support

The Gateworks Ventana Bootloader driver (drivers/thermal/imx_thermal.c) provides several functions:

Vivante GPU thermal management

The Vivante GPU has some frequency scaling based on temperature which enabled by default in the [drivers/mxc/gpu-viv/hal/os/linux/kernel/platform/freescale/gc_hal_kernel_platform_imx6q14.c Vivante driver]. If enabled the driver will scale the GPU frequency down by a specified divisor. By default this is 3/64 for the Gateworks Yocto and Android BSP's.

The GPU frequency scaling is triggered by the IMX thermal zone passive trip point (see above). Note that because the temperature is triggered by the IMX thermal zone, the ARM cpu frequency will be reduced at the same time.

The minimum devisor used to reduce GPU frequency by default is 1 (meaning 1/64th frequency scaling which is the maximum amount of frequency reduction possible) you can use the drivers sysfs interface:

You can change this value from 1 to 64, where 1 is 1/64 frequency (maximum reduction) and 64 is no reduction. Note that depending on what the GPU is being used for, you may want to increase this value. We have found that a value of 3 for example offers adequate cooling without sacrificing significant performance.

}}} == PCIe Switch == Besides the CPU, another item that generates significant heat is the PCIe switch (PLX PEX860x) used on some of the Ventana models (GW520x, GW53xx, GW54xx, GW552x). The typical power usage is appx 1.35W up to a max of appx 2.35W (max being 85% traffic, Gen 1 operation). The switch does support PCIExpress Active State Power Management (ASPM) and also will power down unused SerDes lanes automatically to reduce power when possible. The part is rated as follows: * Max Operating Junction Temp for Reliability = 125C * ThetaJC = 6.12C/W On the GW54xx boards there are topside Mini-PCIe sockets which when used will be directly over the switch. For cases that require the use of these sites, it is recommended to use additional heatsinking or air cooling to keep the switch within the operating temperature range. For low profile heatsinking, Panasonic makes graphite thermal sheets that can be attached to the device and then can extend out and over to the CPU or another area where a larger heatsink can be located. See the following link for information on this material: ​https://industrial.panasonic.com/ww/pgs2/mlpgs (available at Digikey as well).