The reading and writing speed of SD card is too slow. We tested that the reading and writing speed of SD card is only about 1.4mb/s.
This is our dtsi:
We tried to modify dtsi. When we increased the limited frequency range of max-clk-limit, the reading speed of SD card did not improve. When we deleted option max-clk-limit, we could not read SD card.
The frequency of SDIO clock pin measured by oscilloscope is only 3.1mhz.