现在我们做了一块板，GPMC总线接了2个设备，一块256Mbyte的nand flash，使用8-Bit NAND Device模式，一个GPIB协仪芯片，使用的是Non Multiplexed Address Data 8-Bit Device模式，现在有一个奇怪的现像，
1.当接入SD卡，启动项设置为nand启动时没有问题，系统可以正常启动，GPIB芯片也可以正常使用
2.当接入SD卡，启动项设置为SD卡启动时，进到UBOOT找不到nand flash，打印NAND: No NAND device found!!!，启动到内核后可以正常使用GPIB芯片
3.当接入SD卡，启动项设置为SD卡启动，硬件去掉GPIB芯片时，进到UBOOT可以正常使用nand flash
所以，这个问题总结就是，当从SD卡启动时，GPIB连接到GPMC总线就找不到nand flash，去掉GPIB就可以找到nand flash，当从nand flash启动时，可以启动且启动后GPIB芯片可以正常工作，所以我没想明白是什么地方有冲突，上面的测试都使用的同一个uboot，所以感觉和uboot中的配置无关，以下附上我的硬件配置：
/* Pin mux for nand flash module nand的引脚配置 */
static struct pinmux_config nand_pin_mux[] = {
{"gpmc_ad0.gpmc_ad0", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad1.gpmc_ad1", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad2.gpmc_ad2", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad3.gpmc_ad3", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad4.gpmc_ad4", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad5.gpmc_ad5", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad6.gpmc_ad6", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad7.gpmc_ad7", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_wait0.gpmc_wait0", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_wpn.gpmc_wpn", OMAP_MUX_MODE7 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_csn0.gpmc_csn0", OMAP_MUX_MODE0 | AM33XX_PULL_DISA},
{"gpmc_advn_ale.gpmc_advn_ale", OMAP_MUX_MODE0 | AM33XX_PULL_DISA},
{"gpmc_oen_ren.gpmc_oen_ren", OMAP_MUX_MODE0 | AM33XX_PULL_DISA},
{"gpmc_wen.gpmc_wen", OMAP_MUX_MODE0 | AM33XX_PULL_DISA},
{"gpmc_ben0_cle.gpmc_ben0_cle", OMAP_MUX_MODE0 | AM33XX_PULL_DISA},
{NULL, 0},
};
/* Pin mux for gpib module GPIB芯片的引脚配置 */
static struct pinmux_config GPMC_TNT5002_pin_mux[] = {
{"gpmc_ad0.gpmc_ad0", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad1.gpmc_ad1", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad2.gpmc_ad2", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad3.gpmc_ad3", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad4.gpmc_ad4", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad5.gpmc_ad5", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad6.gpmc_ad6", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_ad7.gpmc_ad7", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"gpmc_a1.gpmc_a1", OMAP_MUX_MODE0 | AM33XX_PIN_OUTPUT},
{"gpmc_a2.gpmc_a2", OMAP_MUX_MODE0 | AM33XX_PIN_OUTPUT},
{"gpmc_a3.gpmc_a3", OMAP_MUX_MODE0 | AM33XX_PIN_OUTPUT},
{"gpmc_a6.gpmc_a6", OMAP_MUX_MODE0 | AM33XX_PIN_OUTPUT},
{"gpmc_a7.gpmc_a7", OMAP_MUX_MODE0 | AM33XX_PIN_OUTPUT},
{"gpmc_a8.gpmc_a8", OMAP_MUX_MODE0 | AM33XX_PIN_OUTPUT},
{"gpmc_csn1.gpmc_csn1", OMAP_MUX_MODE0 | AM33XX_PULL_DISA},
{"gpmc_oen_ren.gpmc_oen_ren", OMAP_MUX_MODE0 | AM33XX_PULL_DISA},
{"gpmc_wen.gpmc_wen", OMAP_MUX_MODE0 | AM33XX_PULL_DISA},
{NULL, 0},
};
/* Module pin mux for mmc0 SD卡启动时用的MMC接口 */
static struct pinmux_config mmc0_common_pin_mux[] = {
{"mmc0_dat3.mmc0_dat3", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"mmc0_dat2.mmc0_dat2", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"mmc0_dat1.mmc0_dat1", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"mmc0_dat0.mmc0_dat0", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"mmc0_clk.mmc0_clk", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{"mmc0_cmd.mmc0_cmd", OMAP_MUX_MODE0 | AM33XX_PIN_INPUT_PULLUP},
{NULL, 0},
};
GPIB芯片原理图
