上位機：ubuntu14.04 64bit
下位機:qq2440
交叉編譯器:arm-linux-gcc 3.4.1
下位機使用的linux內核版本:kernel2.6.13
1.插入u盤時錯誤信息如下:
[root@FriendlyARM /home]# usb 1-1: new full speed USB device using s3c2410-ohci and address 6
usb 1-1: device descriptor read/64, error -110
usb 1-1: device descriptor read/64, error -110
usb 1-1: new full speed USB device using s3c2410-ohci and address 7
usb 1-1: device descriptor read/64, error -110
usb 1-1: device descriptor read/64, error -110
usb 1-1: new full speed USB device using s3c2410-ohci and address 8
usb 1-1: device not accepting address 8, error -110
usb 1-1: new full speed USB device using s3c2410-ohci and address 9
usb 1-1: device not accepting address 9, error -110
2.解決方案如下:
2.1修改drivers/usb/host/ohci-s3c2410.c文件，添加以下內容：
a.先添加頭文件#include <mach/regs-clock.h>
b.在s3c2410_start_hc函數中添加以下內容：
unsigned long upllvalue = (0x78 << 12) | (0x02 << 4) | (0x03);
while (upllvalue != __raw_readl(S3C2410_UPLLCON)) {
__raw_writel(upllvalue, S3C2410_UPLLCON);
mdelay(1);
}
添加后的s3c2410_start_hc函數如下:
static void s3c2410_start_hc(struct platform_device *dev, struct usb_hcd *hcd)
{
struct s3c2410_hcd_info *info = dev->dev.platform_data;
dev_dbg(&dev->dev, "s3c2410_start_hc:\n");
clk_enable(clk);
if (info != NULL) {
info->hcd = hcd;
info->report_oc = s3c2410_hcd_oc;
if (info->enable_oc != NULL) {
(info->enable_oc)(info, 1);
}
}
unsigned long upllvalue = (0x78 << 12) | (0x02 << 4) | (0x03);
while (upllvalue != __raw_readl(S3C2410_UPLLCON)) {
__raw_writel(upllvalue, S3C2410_UPLLCON);
mdelay(1);
}
}
2.2總結：以上修改的函數功能是啟動主機控制器,因為usb時鍾設置有問題，因而在開啟主機控制器時修改時鍾,修改后的S3C2410_UPLLCON的值為0xF4100008;
3.注意：本版本內核沒有頭文件regs-clock.h，因而我從其他內核中復制過來的，命令如下:
jello@jello-Inspiron-N4050:~/Downloads/qq2440/linux/kernel-2.6.13$ cp /tftpboot/kernel-2.6.35.7/arch/arm/mach-s3c2410/include/mach/regs-clock.h ./