Upgrading my Chumby 8 kernel part 11: SD/CF card reader

In his blog post, Doug Brown discusses his project to upgrade the Chumby 8 kernel and addresses an issue with the SD/CF card reader creating an empty /dev/sda device even when no cards were inserted. He delves into the technical details of the card reader IC, Alcor Micro AU6350, and the detection pins used to identify inserted cards. Brown explains his solution involving modifying the USB storage driver's probe function and adding GPIO interrupts on card detect pins to manage the device in userspace. He implements a strategy using the usb-storage driver's quirks parameter to ignore the device based on its USB vendor and product ID. Additionally, he develops a userspace daemon to handle card detect GPIO pins, remove the quirk, and connect/disconnect the card reader device accordingly. Brown's approach involves modifying the kernel command line in U-Boot and utilizing sysfs for device management, ultimately resolving the issue without major complications.