tree 5ee4757b0427982c015b57193640133fd9a13cd9
parent 779871240461808a9a52e48343d23551fc125ff9
author Johnathan Mantey <johnathanx.mantey@intel.com> 1602626451 -0700
committer Johnathan Mantey <johnathanx.mantey@intel.com> 1617299193 -0700

Improve initialization of I2C sensors

After an AC cycle validation has witnessed some systems sensors are
missing. As Entity Manager begins the process of scanning for
sesnsors, and creating the hardware monitoring nodes, there are
occassionally some failures to correctly create the node. This
manifests itself by the 'dd' kernel driver emitting an -EBUSY error
message. Unfortunately the 'dd' driver also eats the error code, and
continues. This is by design.

This commit modifies how the nodes are initialized. The steps taken:
1. Determine if the node is already present
2. Create the node if it is not
3. Set a timer, to give the kernel time to create the node
4. For those sensors that create a "hwmon" subdir, search for that
directory after the timer elapses.
5. If the subdir is not present, delete the device, and try again by
initiating another timer.
6. Continue until the subdir exists, or a retry count expires.

Tested:
Ran AC cycles via a script.
After each cycle, wait for the SUT to DC on, and arrive at the EFI
Shell> prompt.
Issue "ipmitool sensor list", capturing the results
Search the list for all of the sensors that have been reported as
missing after AC cycles.

Change-Id: I118df674162677d66e7d211b089430fce384086b
Signed-off-by: Johnathan Mantey <johnathanx.mantey@intel.com>