To: linux-usb@vger.kernel.org
From: Hal Emmerich <hal@halemmerich.com>
Subject: PROBLEM: Regression, USB devices not recognized if plugged in after
 system boots
Message-ID: <aa549aed-b070-f7f0-655d-d61b5ca43284@halemmerich.com>
Date: Thu, 19 Jul 2018 12:03:29 -0500
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101
 Thunderbird/52.9.1
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US

[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


[8.4.] Loaded driver and hardwar
e information (/proc/ioports, /proc/iomem)
00000000-feefffff : System RAM
   00008000-00dfffff : Kernel code
   01000000-011008f3 : Kernel data
ff0c0000-ff0c3fff : dwmmc@ff0c0000
ff0d0000-ff0d3fff : dwmmc@ff0d0000
ff0f0000-ff0f3fff : dwmmc@ff0f0000
ff110000-ff110fff : spi@ff110000
ff130000-ff130fff : spi@ff130000
ff140000-ff140fff : i2c@ff140000
ff160000-ff160fff : i2c@ff160000
ff170000-ff170fff : i2c@ff170000
ff180000-ff18001f : serial
ff190000-ff19001f : serial
ff250000-ff253fff : dma-controller@ff250000
   ff250000-ff253fff : dma-controller@ff250000
ff280000-ff2800ff : tsadc@ff280000
ff500000-ff5000ff : usb@ff500000
ff540000-ff57ffff : usb@ff540000
ff580000-ff5bffff : usb@ff580000
ff650000-ff650fff : i2c@ff650000
ff660000-ff660fff : i2c@ff660000
ff680000-ff68000f : pwm@ff680000
ff680010-ff68001f : pwm@ff680010
ff690000-ff69001f : serial
ff700000-ff717fff : ff700000.bus_intmem
ff720000-ff720fff : ff720000.sram
ff750000-ff7500ff : gpio0@ff750000
ff780000-ff7800ff : gpio1@ff780000
ff790000-ff7900ff : gpio2@ff790000
ff7a0000-ff7a00ff : gpio3@ff7a0000
ff7b0000-ff7b00ff : gpio4@ff7b0000
ff7c0000-ff7c00ff : gpio5@ff7c0000
ff7d0000-ff7d00ff : gpio6@ff7d0000
ff7e0000-ff7e00ff : gpio7@ff7e0000
ff7f0000-ff7f00ff : gpio8@ff7f0000
ff800000-ff8000ff : watchdog@ff800000
ff890000-ff89ffff : i2s@ff890000
ff8a0000-ff8a3fff : cypto-controller@ff8a0000
ff930000-ff93019b : vop@ff930000
ff930300-ff9303ff : iommu@ff930300
ff940000-ff94019b : vop@ff940000
ff940300-ff9403ff : iommu@ff940300
ff970000-ff973fff : dp@ff970000
ff980000-ff99ffff : hdmi@ff980000
ffb20000-ffb23fff : dma-controller@ffb20000
   ffb20000-ffb23fff : dma-controller@ffb20000
ffb40000-ffb4001f : efuse@ffb40000

[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 (like
this
https://github.com/torvalds/linux/commit/d98c624ab3bf9c3c988c3b7d0f24e703061a172f#diff-3a905b19fc3744269a82aeec54a7e405)
did not help.