U盘节点变化_disabled by hub (emi?), re-enabling...

U盘节点变化

问题描述

在工作中有发现一个比较神奇的事情。一般情况下，大家都知道U盘对应的节点是固定的，但恰恰这个节点居然变化了。导致应用在读/写文件的时候有概率会突然断开。

<6>[   37.469082] cfg80211: Exceeded CRDA call max attempts. Not calling CRDA
<13>[   51.900401] init: Service 'bootdvfs' (pid 2562) exited with status 0
<3>[   60.570056] usb usb5-port1: disabled by hub (EMI?), re-enabling...
<6>[   60.576414] rtk-ehci 98013000.ehci: port_event call RTK_usb2_phy_toggle
<6>[   60.576483] rtk-usb-phy-rle0599 98013824.usb_phy_rle0599: rtk_rle0599_phy_toggle ########## to toggle Page1 addr 0xe0 BIT(2)
<3>[   60.577503] usb usb5-port1: port 1, status 0501, change 0002, 480 Mb/s
<6>[   60.584400] usb 5-1: USB disconnect, device number 6
<3>[   60.909092] usb 5-1: new high-speed USB device number 7 using rtk-ehci (platform)
<3>[   60.945344] usb 5-1: device descriptor read/8, error -71
<7>[   60.950818] hub_port_init 4966 clear-set port power 
<3>[   61.759161] usb 5-1: device not accepting address 7, error -22
<3>[   61.766127] hub 5-0:1.0: hub port disable on port 1
<3>[   61.829373] hub 5-0:1.0: hub port disable on port 1
<3>[   61.834460] hub 5-0:1.0: hub port disable on port 1
<6>[   61.859160] rtk-ehci 98013000.ehci: port_event call RTK_usb2_phy_toggle
<6>[   61.859221] rtk-usb-phy-rle0599 98013824.usb_phy_rle0599: rtk_rle0599_phy_toggle ########## to toggle Page1 addr 0xe0 BIT(2)
<3>[   61.860234] usb usb5-port1: port 1, status 0100, change 0001, 12 Mb/s
<6>[   62.059124] rtk-ohci 98013400.ohci: port_event call RTK_usb2_phy_toggle
<6>[   62.059187] rtk-usb-phy-rle0599 98013824.usb_phy_rle0599: rtk_rle0599_phy_toggle ########## to toggle Page1 addr 0xe0 BIT(2)
<3>[   62.060200] usb usb6-port1: port 1, status 0101, change 0000, 12 Mb/s
logcat |grep "hub (EMI?)"
<3>[   62.239081] usb 6-1: new full-speed USB device number 2 using rtk-ohci (platform)
<6>[   62.275114] usb 6-1: not running at top speed; connect to a high speed hub
<6>[   62.295234] scsi host7: usb-storage 6-1:1.0
<5>[   63.296209] scsi 7:0:0:0: Direct-Access     Kingston DataTraveler 2.0 PMAP PQ: 0 ANSI: 6
<5>[   63.306156] sd 7:0:0:0: [sdc] 15249408 512-byte logical blocks: (7.80 GB/7.27 GiB)
<5>[   63.312158] sd 7:0:0:0: [sdc] Write Protect is off
<7>[   63.312171] sd 7:0:0:0: [sdc] Mode Sense: 45 00 00 00
<5>[   63.318145] sd 7:0:0:0: [sdc] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
<6>[   63.363165]  sdc:
<6>[   63.363208] rescan_partitions: rescan device sdc partitions finish.
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从上面可以看出节点由 usb 5-1 --> usb 6-1

(详细的可以见 ls -l /sys/dev/block )

/devices/platform/98013000.ehci/usb5/5-1   --->   /devices/platform/98013000.ehci/usb6/6-1
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问题排查

从日志中分析 ： usb usb5-port1: disabled by hub (EMI?), re-enabling…

从USB驱动代码中看：

            /*
             * EM interference sometimes causes badly shielded USB devices
             * to be shutdown by the hub, this hack enables them again.
             * Works at least with mouse driver.
             */
            if (!(portstatus & USB_PORT_STAT_ENABLE)
                && !connect_change && udev) {
                    dev_err(&port_dev->dev, "disabled by hub (EMI?), re-enabling...\n");
                    connect_change = 1;
            }
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根据提示是EM干扰，那么就是从外部因素开始排查，起初判断是个别U盘的问题，在尝试不同的U盘后，发现有些会出现，有些不会出现。但后续在替换HUB外接线后，任何一个U盘都不会出现。所以判定是HUB外接线的问题（运气比较好）。如果不是以上两个问题点的话，那么就是CPU的问题了，根据电路图知道HUB口是由CPU直接控制的。

此文仅记录本人的工作记录（小白一枚），不喜勿喷，欢迎大家一起学习交流进步，谢谢。