Failed detection of USB flash drive and of second SD card during boot.

[Colin_MTData]

Hello iMX28 users, We are building a device closely based on the iMX28 EVK reference design. The unit boots from the 1st SD card. I find that although the USB device itself is detected during boot, the flash device plugged in it is only some times detected. Sometimes it boots with /dev/sda1 present and sometimes not. Similarly the SD card in the second slot; sometimes /dev/mmcblk1 et al are detected and sometime not. In both cases, once booted, removing and re-inserting them causes the flash devices to appear. In production testing we don't want the operators to have to insert a USB key in the middle of the test procedure, we'd rather it was automated. In the final product the SD cards are internal to the case and if not detected during boot they are never seen. What program, during boot, is detecting the inserted flash device and what can vary to make it work only sometimes? The problem seems to be related to different LTIB builds of the system but even 'good' builds sometimes fail and bad builds sometimes work. Is the program in question udev and is there an obvious prerequisite that I should check for, for it to work? Is the rcS script starting udev too early? The attached boot log shows the failing case. The successful case continues after the line: usb 1-1: SerialNumber: GSAUTC06171103000190 with: Initializing USB Mass Storage driver... scsi0 : usb-storage 1-1:1.0 usbcore: registered new interface driver usb-storage USB Mass Storage support registered. scsi 0:0:0:0: Direct-Access Generic Flash Disk 8.07 PQ: 0 ANSI: 2 sd 0:0:0:0: Attached scsi generic sg0 type 0 sd 0:0:0:0: [sda] 4194304 512-byte logical blocks: (2.14 GB/2.00 GiB) sd 0:0:0:0: [sda] Write Protect is off sd 0:0:0:0: [sda] Assuming drive cache: write through sd 0:0:0:0: [sda] Assuming drive cache: write through sda: sda1 sd 0:0:0:0: [sda] Assuming drive cache: write through sd 0:0:0:0: [sda] Attached SCSI removable disk