Hi, I'm trying to bring up a marvell 8787 based wifi chip on an atmel sama5d2 based board. The kernel version I'm on is 4.4 (specific version is at https://github.com/linux4sam/linux-at91/tree/linux4sam_5.5). The wifi controller is a WYSBMVGXB from TAIYO YUDEN. The device tree configuration for the mmc bus I've used is as follows: sdmmc1: sdio-host@b0000000 { pinctrl-names = "default"; pinctrl-0 = <&pinctrl_sdmmc1_default>; mmc-pwrseq = <&sdhci0_pwrseq>; bus-width = <4>; broken-cd; status = "okay"; /* conflict with qspi0 */ }; I've used a modified pwrseq driver that drives the IO as specified in the controller data sheet and confirmed that the lines are controlled as expected during startup. I can also see some clock activity on the sdio bus, but doesn't seem to detect a device on the bus. The mwifiex_sdio driver is statically compiled. Can anyone offer any suggestions on how I can debug this issue? Also, I don't quite understand how the mwifiex_sdio driver is attached to that specific bus. My understanding based on the i2c, spi buses are, the device tree can specify the devices hanging off these buses and the appropriate driver is loaded. However, the mmc/sdio dts entries dob't seem to be following the same pattern. Thank you and regards, Dushara