xiaojianjun 
Hey, I'm working at a mini2440 board with a linux kernel embbeded in a 128MB nand flash and a shell of busybox saved in a sd card.Now I encountered a very strange problem that the board sometimes can detect the SD card correctly,but sometimes not. I googled about this issue.and I found that the chipsets of SD cards which can be detected are all made by SAMSANG.The driver of mmc controller in the kernel 2.6.29 is also for SAMSANG.Is there anything related to the vender of the chipset. SD card that can be detected correctly: s3c2440-sdi s3c2440-sdi: powered down. s3c2440-sdi s3c2440-sdi: initialisation done. s3c2440-sdi s3c2440-sdi: running at 0kHz (requested: 0kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). usbcore: registered new interface driver usbhid usbhid: v2.6:USB HID core driver Advanced Linux Sound Architecture Driver Version 1.0.18a. No device for DAI UDA134X No device for DAI s3c24xx-i2s S3C24XX_UDA134X SoC Audio driver s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). UDA134X SoC Audio Codec s3c2440-sdi s3c2440-sdi: running at 16875kHz (requested: 25000kHz). s3c2440-sdi s3c2440-sdi: running at 16875kHz (requested: 25000kHz). mmc0: new SD card at address 0001 asoc: UDA134X <-> s3c24xx-i2s mapping ok mmcblk0: mmc0:0001 00000 1.89 GiB mmcblk0: p1 p2 SD card that can not be detected: s3c2440-sdi s3c2440-sdi: powered down. s3c2440-sdi s3c2440-sdi: initialisation done. s3c2440-sdi s3c2440-sdi: running at 0kHz (requested: 0kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). s3c2440-sdi s3c2440-sdi: running at 198kHz (requested: 197kHz). usbcore: registered new interface driver usbhid usbhid: v2.6:USB HID core driver Advanced Linux Sound Architecture Driver Version 1.0.18a. No device for DAI UDA134X No device for DAI s3c24xx-i2s S3C24XX_UDA134X SoC Audio driver UDA134X SoC Audio Codec asoc: UDA134X <-> s3c24xx-i2s mapping ok ALSA device list: #0: S3C24XX_UDA134X (UDA134X) TCP cubic registered lib80211: common routines for IEEE802.11 drivers s3c2410-rtc s3c2410-rtc: setting system clock to 2010-06-01 17:41:57 UTC (1275414117) VFS: Cannot open root device "mmcblk0p1" or unknown-block(0,0) Please append a correct "root=" boot option; here are the available partitions: 1f00 192 mtdblock0 (driver?) 1f01 2048 mtdblock1 (driver?) 1f02 63152 mtdblock2 (driver?) Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) Is there anybody know something about this issue. Thanks!