> On Sun, Apr 26, 2020 at 09:25:46AM +0800, rui_feng@xxxxxxxxxxxxxx wrote: > > From: Rui Feng <rui_feng@xxxxxxxxxxxxxx> > > > > RTS5261 support legacy SD mode and SD Express mode. > > In SD7.x, SD association introduce SD Express as a new mode. > > SD Express mode is distinguished by CMD8. > > Therefore, CMD8 has new bit for SD Express. > > SD Express is based on PCIe/NVMe. > > RTS5261 uses CMD8 to switch to SD Express mode. > > So how does this bit work? They way I imagined SD Express to work is that > the actual SD Card just shows up as a real PCIe device, similar to say > Thunderbolt. New SD Express card has dual mode. One is SD mode and another is PCIe mode. In PCIe mode, it act as a PCIe device and use PCIe protocol not Thunderbolt protocol.
