Sierra Wireless AC850 is working fine under Linux thanks to a firmware provided by Sierra but there is problem in firmware detection which is explained in this document.
The latest linux kernels are able to automatically load firmware for pcmcia card. The idea is cleanly implemented. For example, let’s see how it detects the “Sierra Wireless AC710” in serial_cs.c:
PCMCIA_DEVICE_CIS_MANF_CARD(0x0192, 0x0710, “SW_7xx_SER.cis”), /* Sierra Wireless AC710/AC750 GPRS Network Adapter R1 */
It uses manufacturer ID “0x0192, 0x0710” to detect the model of the card.
It’s fine if the manufacturer does a good job. This is not te case as for “Sierra Wireless AC850 3G Network Adapter R1”, the manufacturer ID is also “0x0192, 0x0710”. The problem is that for this card the firmware is different and provided under the name of “SW_8xx_SER.dat”.
The effect is that, if you follows sierra wireless documentation, the firmware will not be loaded. A solution is to copy the file “SW_8xx_SER.dat” to “SW_7xx_SER.cis” in the “/lib/firmware” directory. This cheats Linux which load the correct firmware under a bad name.
I’ve finally found some time to patch this issue and send the resulting work to the Linux Kernel Mailing list: Add support for PCMCIA card Sierra Wireless AC850.
The patch has hit mainstream and 2.6.24 contains the fix.