Hi, I developed a hardware that has a Microchip USB2642 (USB Hub with MMC interface, former SMSC, former ChipIdea), which is kernel supported by chipidea IP (ci_hdrc) driver. I connected a Bluegiga WF111-A WiFi module to the MMC interface of the USB2642. So, in a hardware sense, everything is fine. This USB2642 chip is dual-role USB Hub with a SD card interface and compatible with USB Mass Storage spec. The problem is that the only driver available from BlueGiga uses linux MMC stack. So although usb-storage detects the module as a SCSI disk interface (/dev/sda), the driver doesn't work, as it searches the MMC stack for the module, and finds nothing. The document at http://ww1.microchip.com/downloads/en/DeviceDoc/50002277A.pdf specifies a SCSI command set to passthrough SDIO communication on top of Mass Storage interface. I see myself with 2 options: rewrite the driver or implementing something in linux to "link" the Mass Storage interface and SDIO. I started a thread at linux-usb asking for guidance in using usb-storage layer and got a much better approach, which would be implementing a "custom" sdio_bus that actually uses SCSI as client to send the commands. Taking a look at sdio implementation it seems this is not easily doable without changing how sdio_bus works (it seems tight up with mmc stack, no "multiple" sdio_buses possible right now). Taking a look at sdio implementation, I think that to allow a MMC driver to attach to the MMC stack (using sdio_register_driver) and also use the USB Mass Storage bridge provided by the chip, I could write a MMC host that is actually a SCSI client and sends the commands through the SCSI layer as specified by the referenced document. In this case, I would be able to achieve the goal of using the existing BlueGiga driver (which register itself using sdio_register_driver) and don't mess around the mmc core implementation. Can someone with better experience on MMC stack tell me this is the right approach? Thanks in advance! -- Raphael Derosso Pereira -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
