We are using a Sabrelite board (i.MX6Q) with 3.0.35 kernel. The host supports UHS-I SDR 50 and 104 modes. However when we plug in a UHS-I SD card to usdhc3, we see that it gets detected as a "High speed device" rather than a 'ultra high speed device'. Browsing through the sources, we found that to for the SD card to work in UHS mode, the host needs to switch to 1.8v from 3.3v.
Looks like Sabrelite does not support this voltage level and hence restricts this switch over. The result being that though there is a UHS SD card its get detected as a high-speed device, also limiting the data throughput rates.
Is this understanding correct? Has anyone come across a similar scenario?
Any pointers to enable the UHS-I support will be helpful.