(Relevant part numbers: Si4x55-C2A, Si4x6x-C2A, Si446x-A2A)
It is described in detail in section "9.6. Patching the Radio" of
The EZRadio and EZRadio Pro Family Rev C2A/A2A Device Errata contains this information.
It is important to verify the exact device part number and revision.
This can be identified by the top marking of the package or by the replay of the PART_INFO API command.
See details in the article Using PART_INFO command to identify EZRadio/PRO part number
If you are affected by an errata item that has a patch fix, you should apply that patch.
The latest patches are attached to this article.
(Recently a new patch (ID 0x4668) was created, that replaces patch 0xCA90,
and an other (ID 0xD046) that replaces patch 0x80FE.
Both are fixing an additional new errata item (#13), that was added to the latest release of the errata.)
Yes, if WDS was updated since the latest patch release.
WDS stores the patch files at C:\Program Files (x86)\SiliconLabs\WDS3\Patch\ .
It is always advised to make sure the proper patch is applied by WDS, and to correct if necessary.
(Currently latest WDS v.188.8.131.52 / 16.12.2016 does not contain the latest patches.
In the WDS patch folder the content of Si446x_C2_GENERAL.csg should be replaced by fw_6_0_2_4668.csg
The content of Si446x_A2_PSM.csg should be replaced by fw_6_0_7_D046.csg
The original WDS filenames should be kept.)
After patching and executing the POWER_UP API command, you can get back the patch ID as the PATCH replay field of the FUNC_INFO API command.