调试笔记

static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
{
        ...

        mmc_wait_for_req(card->host, &brq.mrq);

        ...
        if (brq.cmd.error) {
            printk(KERN_ERR "%s: error %d sending read/write "
             "command, response %#x, card status %#x\n",
             req->rq_disk->disk_name, brq.cmd.error,
             brq.cmd.resp[0], status);
        }
        ...
}

从这个错误入手，分析一下出错流程。

 

分析mmc_sd_init_card()

 

static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
    struct mmc_card *oldcard)
{
    ...
    mmc_go_idle(host);

    /*
     * If SD_SEND_IF_COND indicates an SD 2.0
     * compliant card and we should set bit 30
     * of the ocr to indicate that we can handle
     * block-addressed SDHC cards.
     */
    err = mmc_send_if_cond(host, ocr);
    if (!err)
        ocr |= 1 << 30;

    err = mmc_send_app_op_cond(host, ocr, NULL);
    if (err)
        goto err;

    /*
     * Fetch CID from card.
     */
    if (mmc_host_is_spi(host))
        err = mmc_send_cid(host, cid);
    else
        err = mmc_all_send_cid(host, cid);
    if (err)
        goto err;

    ...

    /*
     * For native busses: get card RCA and quit open drain mode.
     */
    if (!mmc_host_is_spi(host)) {
        err = mmc_send_relative_addr(host, &card->rca);
        if (err)
            goto free_card;

        mmc_set_bus_mode(host, MMC_BUSMODE_PUSHPULL);
    }

    if (!oldcard) {
        /*
         * Fetch CSD from card.
         */
        err = mmc_send_csd(card, card->raw_csd);
        if (err)
            goto free_card;

        err = mmc_decode_csd(card);
        if (err)
            goto free_card;

        mmc_decode_cid(card);
    }

    /*
     * Select card, as all following commands rely on that.
     */
    if (!mmc_host_is_spi(host)) {
        err = mmc_select_card(card);
        if (err)
            goto free_card;
    }

    if (!oldcard) {
        /*
         * Fetch SCR from card.
         */
        err = mmc_app_send_scr(card, card->raw_scr);
        if (err)
            goto free_card;

        err = mmc_decode_scr(card);
        if (err < 0)
            goto free_card;
        /*
         * Fetch switch information from card.
         */
#ifdef CONFIG_MMC_PARANOID_SD_INIT
        for (retries = 1; retries <= 3; retries++) {
            err = mmc_read_switch(card);
            if (!err) {
                if (retries > 1) {
                    printk(KERN_WARNING
                     "%s: recovered\n",
                     mmc_hostname(host));
                }
                break;
            } else {
                printk(KERN_WARNING
                 "%s: read switch failed (attempt %d)\n",
                 mmc_hostname(host), retries);
            }
        }
#else
        err = mmc_read_switch(card);
#endif

        if (err)
            goto free_card;
    }

    ...

    /*
     * Attempt to change to high-speed (if supported)
     */
    err = mmc_switch_hs(card);
    if (err)
        goto free_card;

    /*
     * Compute bus speed.
     */
    max_dtr = (unsigned int)-1;

    if (mmc_card_highspeed(card)) {
        if (max_dtr > card->sw_caps.hs_max_dtr)
            max_dtr = card->sw_caps.hs_max_dtr;
    } else if (max_dtr > card->csd.max_dtr) {
        max_dtr = card->csd.max_dtr;
    }

    mmc_set_clock(host, max_dtr);

    /*
     * Switch to wider bus (if supported).
     */
    if ((host->caps & MMC_CAP_4_BIT_DATA) &&
        (card->scr.bus_widths & SD_SCR_BUS_WIDTH_4)) {
        err = mmc_app_set_bus_width(card, MMC_BUS_WIDTH_4);
        if (err)
        {
            err = 0;
            printk(KERN_ERR "HiGH-SPEED MODE NOT AVILABLE FOR YOUR CARD!\n");
            mmc_set_timing(card->host,MMC_TIMING_LEGACY);
            err = mmc_app_set_bus_width(card, MMC_BUS_WIDTH_4);
            if(err)
            {
                err = 0;
                printk(KERN_ERR "CLOCK TOO HIGH SWITCH TO NORMAL CLOCK!\n");
                max_dtr = card->csd.max_dtr;
                mmc_set_clock(host, max_dtr);
                err = mmc_app_set_bus_width(card, MMC_BUS_WIDTH_4);
                if(err)
                {
                    printk("I don't known why!!\n");
                    goto free_card;
                }

            }
        }
        mmc_set_bus_width(host, MMC_BUS_WIDTH_4);
    }

    /*
     * Check if read-only switch is active.
     */
    if (!oldcard) {
        if (!host->ops->get_ro || host->ops->get_ro(host) < 0) {
            printk(KERN_WARNING "%s: host does not "
                "support reading read-only "
                "switch. assuming write-enable.\n",
                mmc_hostname(host));
        } else {
            if (host->ops->get_ro(host) > 0)
                mmc_card_set_readonly(card);
        }
    }

    if (!oldcard)
        host->card = card;

    return 0;

free_card:
    if (!oldcard)
        mmc_remove_card(card);
err:

    return err;
}


分析mmc_read_switch()和mmc_switch_hs()，这两个都调mmc_sd_switch()，分析SD的SD_SWITCH命令是干什么的？

 

 

=======================

 

1. 在L1456处加Log

2. L1362处Log不要打印devpath

3. L462恢复原状

 

=======================

 

ehci_hcd_init最后初始化ehci控制器，ehci_imapx200_init

usb_init后来usb_hub_init然后起一个线程hub_thread轮询端口的变化

这两者什么关系，谁先谁后？

 

这里提到了debugfs

http://blog.csdn.net/fudan_abc/archive/2007/10/01/1809273.aspx

 

这里分析了hub_thread线程

http://blog.csdn.net/zkami/archive/2008/06/02/2504485.aspx

 

在usb_devio_init里注册了一个notify，usb_register_notify(&usbdev_nb);其回调函数是usbdev_notify，这个notify的作用？

 

static int usbdev_notify(struct notifier_block *self,
             unsigned long action, void *dev)
{
    switch (action) {
    case USB_DEVICE_ADD:
        if (usb_classdev_add(dev))
            return NOTIFY_BAD;
        break;
    case USB_DEVICE_REMOVE:
        usb_classdev_remove(dev);
        usbdev_remove(dev);
        break;
    }
    return NOTIFY_OK;
}

HOWTO: 打开dev_dbg()调试信息

在#include <linux/device>前加#define DEBUG 1