[1.] One line summary of the problem: Regression, USB devices not recognized if plugged in after system boots [2.] Full description of the problem/report: If a usb device is plugged in before system begins booting into the kernel, it will be recognized once boot completes. However, if a usb device is plugged in once boot completes the system will not recognized it, no messages are added to dmesg. If CONFIG_USB_DWC2_DEBUG is set to yes, two messages are added to dmesg when a usb device is plugged in: dwc2 ff580000.usb: gintsts=40000001 gintmsk=f0000000 dwc2 ff580000.usb: Session request interrupt - lx_state=2 ##Reverting the merge made at commit 6d23ee9caa6790aea047f9aca7f3c03cb8d96eb6 (The main 4.17 merge) fixes the issue## [3.] Keywords (i.e., modules, networking, kernel): usb, dwc2, kernel, arm [4.] Kernel information: [4.1.] Kernel version (from /proc/version): Linux version 4.17.6 (root@debian-build) (gcc version 5.4.1 20160919 (15:5.4.1+svn241155-1)) #1 SMP PREEMPT Thu Jul 12 21:40:35 CDT 2018 [4.2.] Kernel .config file: [5.] Most recent kernel version which did not have the bug: 4.16.18 [6.] Output of Oops.. message (if applicable) with symbolic information resolved (see Documentation/admin-guide/bug-hunting.rst) [7.] A small shell script or example program which triggers the problem (if possible) [8.] Environment [8.1.] Software (add the output of the ver_linux script here) [8.2.] Processor information (from /proc/cpuinfo): processor : 0 model name : ARMv7 Processor rev 1 (v7l) BogoMIPS : 48.00 Features : half thumb fastmult vfp edsp thumbee neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm CPU implementer : 0x41 CPU architecture: 7 CPU variant : 0x0 CPU part : 0xc0d CPU revision : 1 processor : 1 model name : ARMv7 Processor rev 1 (v7l) BogoMIPS : 48.00 Features : half thumb fastmult vfp edsp thumbee neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm CPU implementer : 0x41 CPU architecture: 7 CPU variant : 0x0 CPU part : 0xc0d CPU revision : 1 processor : 2 model name : ARMv7 Processor rev 1 (v7l) BogoMIPS : 48.00 Features : half thumb fastmult vfp edsp thumbee neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm CPU implementer : 0x41 CPU architecture: 7 CPU variant : 0x0 CPU part : 0xc0d CPU revision : 1 processor : 3 model name : ARMv7 Processor rev 1 (v7l) BogoMIPS : 48.00 Features : half thumb fastmult vfp edsp thumbee neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm CPU implementer : 0x41 CPU architecture: 7 CPU variant : 0x0 CPU part : 0xc0d CPU revision : 1 Hardware : Rockchip (Device Tree) Revision : 0000 Serial : 0000000000000000 [8.3.] Module information (from /proc/modules): vfat 20480 1 - Live 0xbf16f000 fat 65536 1 vfat, Live 0xbf158000 ath9k_htc 65536 0 - Live 0xbf140000 ath9k_common 16384 1 ath9k_htc, Live 0xbf137000 ath9k_hw 360448 2 ath9k_htc,ath9k_common, Live 0xbf0d1000 ath 24576 3 ath9k_htc,ath9k_common,ath9k_hw, Live 0xbf0c7000 mac80211 561152 1 ath9k_htc, Live 0xbf00f000 autofs4 36864 2 - Live 0xbf000000 [8.5.] PCI information ('lspci -vvv' as root) N/A [8.6.] SCSI information (from /proc/scsi/scsi) N/A [8.7.] Other information that might be relevant to the problem (please look in /proc and include all information that you think to be relevant): [X.] Other notes, patches, fixes, workarounds: Reverting the merge made at commit 6d23ee9caa6790aea047f9aca7f3c03cb8d96eb6 fixes the issue Walking through the dmesg logs with and without that commit I found this difference at the same point in the boot process: dwc2 ff540000.usb: In host mode, hprt0=00001501 With the non-functional commit dwc2 ff540000.usb: In host mode, hprt0=00001101 This difference corresponds to bit 10 being set in the hprt0 register, but I can’t tell what this bits function is in hw.h disabling power_down and lpm in dwc2_set_his_params in params.c did not help. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html