We used the chip am3356, and we connected a wifi module through the sdio interface. In the process of speed measurement, we found that the rates of 11a and 11n were very poor. The manufacturer of the wifi module required our SDIO clock to keep in regular supply, so that the wifi module could be used normally. We measured the CLK of SDIO through the oscilloscope, which is not in the usual state as shown in the figure below. We tried to modify the following registers of am3356, but found that the clock of sdio was still the same as before after setting. We need to find a way to keep sdio's clock always running.
