#### Why I did it
According to thermalctld hld, each fan must belong to a fan drawer, if the fan drawer does not physically exist, put fan into a virtual fan drawer. This PR is to clear fan from chassis._fan_list
#### How I did it
1. Don't put fan to chassis._fan_list
2. Always query fan from fan_drawer
Originally, SFP modules were always accessed from platform daemons, and arbitrary SFP modules can be accessed in the daemon. So all SFP modules were initialized in one shot once one of the following chassis APIs called
- get_all_sfps
- get_sfp_numbers
- get_sfp
Recently, we noticed that SFP modules can also be accessed from CLI, eg. the latest refactor of `sfputil`.
In this case, only one SFP module is accessed in the chassis object's life cycle.
To initialize all SFP modules in one shot is waste of time and causes the CLI to take much more time to finish.
So we would like to optimize the initialization flow by introducing a two-phase initialization approach:
- Partial initialization, which means the `chassis._sfp_list` has been initialized with proper length and all elements being `None`
- Full initialization, which means all elements in `chassis._sfp_list` are created
If the relevant function is called,
- `get_sfp`, only partial initialization will be done, and then the specific SFP module is initialized.
- `get_all_sfps` or `get_num_sfps`, full initialization will be done, which means all SFP modules are initialized.
Signed-off-by: Stephen Sun <stephens@nvidia.com>
**- Why I did it**
After migrating to python3, the operator '/' always get a float result, but it gets integer result in python2. Need fix this in thermal_conditions.
**- How I did it**
1. cast float value to int
2. change the unit test case to cover this situation
**- How to verify it**
Manually test and regression test
In order to support SONiC physical entity mib extension, a few new platform API are added to sonic-platform-common, this PR is to provide an mellanox platform implementation for those new APIs.
* [thermal control] Fix pmon docker stop issue on 3800
* [thermal fix] Fix QA test issue
* [thermal fix] change psu._get_power_available_status to psu.get_power_available_status
* [thermal fix] adjust log for PSU absence and power absence
* [thermal fix] add unit test for loading thermal policy file with duplicate conditions in different policies
* [thermal] fix fan.get_presence for non-removable SKU
* [thermal fix] fix issue: fan direction is based on drawer
* Fix issue: when fan is not present, should not read fan direction from sysfs but directly return N/A
* [thermal fix] add unit test for get_direction for absent FAN
* Unplugable PSU has no FAN, no need add a FAN object for this PSU
* Update submodules
Co-authored-by: Stephen Sun <5379172+stephenxs@users.noreply.github.com>
