TI351 M.2 1216 solder down module does not enumerate

Answer

The SDIO_WAKE#/HOST_IRQ_WL signal is a SenseOnPower pin that must be low at the input to the cc3351 chip itself when the device is powered up. There is an internal pull-down on this signal, but the host platform must ensure it is not driven high before the Sona TI351 is powered up. If that cannot be guaranteed, this signal must be buffered.

This signal is the active high HOST_IRQ_WL signal when using the M.2 1216 module. It is inverted on the M.2 2230 carrier board and exposed as SDIO_WAKE# to make it active low for M.2 compliance. This issue does not apply to the M.2 2230 module variant because that inverter buffers the HOST_IRQ_WL signal from the host.

Please see the Sona TI Software Integration Guide for more information and a sample Device Tree.