Hi ,
We are having i.MX6UL soc based custom board and AW-CM276NF WIFI card connected to usdhc1 (mmc@2190000). Currently, Interface is up but ping test get failed (Destination Host unreachable) after sometime (~17 sec). We checked mmc0 clock frequency (/sys/kernel/debug/mmc0/clock) which is 198MHz and USDHC1_CLK voltage is 1.2V and CMD/DATA lines voltage is 1.8V.
We tried by reducing to 100 Mhz and checked ping test (more that 10 hours). It runs well without any issues. Also, USDHC1_CLK voltage is 1.8V. Since WIFI bandwidth will be limited for 100 MHz, we can't use.
We suspected that clock voltage causing issue and tried to improve USDHC1_CLK pad drive strength (DSE) with below options but didn't get succeeds.
011 - DSE_3_R0_3 — R0/3
101 - DSE_5_R0_5 — R0/5
110 - DSE_6_R0_6 — R0/6
111 - DSE_7_R0_7 — R0/7
Please find the kernel device tree settings as below,
&usdhc1 {
pinctrl-names = "default", "state_100mhz", "state_200mhz";
pinctrl-0 = <&pinctrl_usdhc1>;
pinctrl-1 = <&pinctrl_usdhc1_100mhz>;
pinctrl-2 = <&pinctrl_usdhc1_200mhz>;
bus-width = <4>;
keep-power-in-suspend;
status = "okay";
};
pinctrl_usdhc1: usdhc1grp {
fsl,pins = <
MX6UL_PAD_SD1_CMD__USDHC1_CMD 0x17059
MX6UL_PAD_SD1_CLK__USDHC1_CLK 0x10071
MX6UL_PAD_SD1_DATA0__USDHC1_DATA0 0x17059
MX6UL_PAD_SD1_DATA1__USDHC1_DATA1 0x17059
MX6UL_PAD_SD1_DATA2__USDHC1_DATA2 0x17059
MX6UL_PAD_SD1_DATA3__USDHC1_DATA3 0x17059
>;
};
pinctrl_usdhc1_100mhz: usdhc1grp100mhz {
fsl,pins = <
MX6UL_PAD_SD1_CMD__USDHC1_CMD 0x170b9
MX6UL_PAD_SD1_CLK__USDHC1_CLK 0x100b9
MX6UL_PAD_SD1_DATA0__USDHC1_DATA0 0x170b9
MX6UL_PAD_SD1_DATA1__USDHC1_DATA1 0x170b9
MX6UL_PAD_SD1_DATA2__USDHC1_DATA2 0x170b9
MX6UL_PAD_SD1_DATA3__USDHC1_DATA3 0x170b9
>;
};
pinctrl_usdhc1_200mhz: usdhc1grp200mhz {
fsl,pins = <
MX6UL_PAD_SD1_CMD__USDHC1_CMD 0x170f9
MX6UL_PAD_SD1_CLK__USDHC1_CLK 0x100f9
MX6UL_PAD_SD1_DATA0__USDHC1_DATA0 0x170f9
MX6UL_PAD_SD1_DATA1__USDHC1_DATA1 0x170f9
MX6UL_PAD_SD1_DATA2__USDHC1_DATA2 0x170f9
>;
};
Please help us to solve this issue.
