How to limit speed if board has bad signal quality?
- uhs-mask: Specify modes that are masked for the device Mask HS200 mode: 0x20 Mask HS400 mode: 0x40 Mask SDR104 mode: 0x10 Mask SDR50 mode: 0x4 Mask DDR50 mode: 0x8 Mask SDR25 mode: 0x2
tegra_sdhci_mask_host_caps() from $kernel/kernel/kernel-4.9/drivers/mmc/host/sdhci-tegra.c
If SDR104 can't supported by hardware limitation, uhs-mask should set to:
0x70 : which means support "SD_HS|DDR50|SDR50|SDR25|SDR12"
0x78 : which means support "SD_HS|SDR50|SDR25|SDR12"