dwc2: Dealing with power domains

Stefan Wahren wahrenst at gmx.net
Fri Jul 12 12:18:14 PDT 2024 

Hi,

Am 11.07.24 um 19:25 schrieb Stefan Wahren:
> Hi,
> I currently work on suspend to idle support for Raspberry Pi (BCM2835)
> [1]. Unfortunately properly powering down USB (dwc2) is currently not
> supported for this platform. As soon as the USB power domain is
> powered down and up (triggered by suspend to idle), the USB interface
> is functionally dead (no devices available, no enumeration) and resume
> take a lot of time:
>
> Apr 24 16:14:08 raspberrypi kernel: [  271.494472] PM: suspend entry
> (s2idle)
> Apr 24 16:14:09 raspberrypi kernel: [  272.009042] Filesystems sync:
> 0.514 seconds
> Apr 24 16:15:23 raspberrypi kernel: [  272.054081] Freezing user space
> processes
> Apr 24 16:15:23 raspberrypi kernel: [  272.058478] Freezing user space
> processes completed (elapsed 0.004 seconds)
> Apr 24 16:15:23 raspberrypi kernel: [  272.058574] OOM killer disabled.
> Apr 24 16:15:23 raspberrypi kernel: [  272.058594] Freezing remaining
> freezable tasks
> Apr 24 16:15:23 raspberrypi kernel: [  272.060095] Freezing remaining
> freezable tasks completed (elapsed 0.001 seconds)
> Apr 24 16:15:23 raspberrypi kernel: [  272.068302] smsc95xx 1-1.1:1.0
> eth0: entering SUSPEND2 mode
> Apr 24 16:15:23 raspberrypi kernel: [  272.123910] dwc2 20980000.usb:
> dwc2_suspend
> Apr 24 16:15:23 raspberrypi kernel: [  272.123973] dwc2 20980000.usb:
> __dwc2_lowlevel_hw_disable()
> Apr 24 16:15:23 raspberrypi kernel: [  272.126143] PM: suspend of
> devices complete after 65.371 msecs
> Apr 24 16:15:23 raspberrypi kernel: [  272.126221] PM: start suspend
> of devices complete after 66.043 msecs
> Apr 24 16:15:23 raspberrypi kernel: [  272.127886] PM: late suspend of
> devices complete after 1.625 msecs
> Apr 24 16:15:23 raspberrypi kernel: [  272.129312] USB domain off
> Apr 24 16:15:23 raspberrypi kernel: [  272.130636] PM: noirq suspend
> of devices complete after 2.547 msecs
> Apr 24 16:15:23 raspberrypi kernel: [  272.130714] PM: suspend debug:
> Waiting for 5 second(s).
> Apr 24 16:15:23 raspberrypi kernel: [  277.141198] USB domain on
> Apr 24 16:15:23 raspberrypi kernel: [  277.669113] PM: noirq resume of
> devices complete after 533.149 msecs
> Apr 24 16:15:23 raspberrypi kernel: [  277.670324] PM: early resume of
> devices complete after 0.994 msecs
> Apr 24 16:15:23 raspberrypi kernel: [  277.672005] dwc2 20980000.usb:
> dwc2_resume
> Apr 24 16:15:23 raspberrypi kernel: [  277.672061] dwc2 20980000.usb:
> __dwc2_lowlevel_hw_enable()
> Apr 24 16:15:23 raspberrypi kernel: [  282.943909] usb 1-1: reset
> high-speed USB device number 2 using dwc2
> Apr 24 16:15:23 raspberrypi kernel: [  288.223658] usb 1-1: device
> descriptor read/64, error -110
> Apr 24 16:15:23 raspberrypi kernel: [  303.663648] usb 1-1: device
> descriptor read/64, error -110
> Apr 24 16:15:23 raspberrypi kernel: [  304.003656] usb 1-1: reset
> high-speed USB device number 2 using dwc2
> Apr 24 16:15:23 raspberrypi kernel: [  309.263662] usb 1-1: device
> descriptor read/64, error -110
> Apr 24 16:15:23 raspberrypi kernel: [  324.703663] usb 1-1: device
> descriptor read/64, error -110
> Apr 24 16:15:23 raspberrypi kernel: [  325.043664] usb 1-1: reset
> high-speed USB device number 2 using dwc2
> Apr 24 16:15:23 raspberrypi kernel: [  335.583640] usb 1-1: device not
> accepting address 2, error -110
> Apr 24 16:15:23 raspberrypi kernel: [  335.803642] usb 1-1: reset
> high-speed USB device number 2 using dwc2
> Apr 24 16:15:23 raspberrypi kernel: [  346.383608] usb 1-1: device not
> accepting address 2, error -110
> Apr 24 16:15:23 raspberrypi kernel: [  346.463987] PM: resume of
> devices complete after 68793.584 msecs
> Apr 24 16:15:23 raspberrypi kernel: [  346.464352] smsc95xx 1-1.1:1.0
> eth0: Link is Down
> Apr 24 16:15:23 raspberrypi kernel: [  346.465369] OOM killer enabled.
> Apr 24 16:15:23 raspberrypi kernel: [  346.465417] Restarting tasks
> ... done.
> Apr 24 16:15:23 raspberrypi kernel: [  346.500347] random: crng
> reseeded on system resumption
> Apr 24 16:15:23 raspberrypi kernel: [  346.500928] usb 1-1: USB
> disconnect, device number 2
> Apr 24 16:15:23 raspberrypi kernel: [  346.500993] usb 1-1.1: USB
> disconnect, device number 3
> Apr 24 16:15:23 raspberrypi kernel: [  346.501599] smsc95xx 1-1.1:1.0
> eth0: unregister 'smsc95xx' usb-20980000.usb-1.1, smsc95xx USB 2.0
> Ethernet
> Apr 24 16:15:23 raspberrypi kernel: [  346.501808] smsc95xx 1-1.1:1.0
> eth0: hardware isn't capable of remote wakeup
> Apr 24 16:15:23 raspberrypi kernel: [  346.508950] usb 1-1.2: USB
> disconnect, device number 4
> Apr 24 16:15:24 raspberrypi kernel: [  346.535846] PM: suspend exit
> Apr 24 16:15:24 raspberrypi kernel: [  346.783703] usb 1-1: new
> high-speed USB device number 5 using dwc2
> Apr 24 16:15:29 raspberrypi kernel: [  352.063614] usb 1-1: device
> descriptor read/64, error -110
> Apr 24 16:15:44 raspberrypi kernel: [  367.503622] usb 1-1: device
> descriptor read/64, error -110
> Apr 24 16:15:45 raspberrypi kernel: [  367.843649] usb 1-1: new
> high-speed USB device number 6 using dwc2
> Apr 24 16:15:50 raspberrypi kernel: [  373.103627] usb 1-1: device
> descriptor read/64, error -110
> Apr 24 16:16:06 raspberrypi kernel: [  388.543616] usb 1-1: device
> descriptor read/64, error -110
> Apr 24 16:16:06 raspberrypi kernel: [  388.663808] usb usb1-port1:
> attempt power cycle
>
just some more information about the resume issue:

Regdump before suspend (working):
GOTGCTL = 0x001c0001
GOTGINT = 0x00000000
GAHBCFG = 0x00000031
GUSBCFG = 0x20001707
GRSTCTL = 0x80000000
GINTSTS = 0x04000021
GINTMSK = 0xf300080e
GRXSTSR = 0x41767c40
GRXFSIZ = 0x00000306
GNPTXFSIZ = 0x01000306
GNPTXSTS = 0x00080100
GI2CCTL = 0x00000000
GPVNDCTL = 0x00000000
GGPIO = 0x00000000
GUID = 0x2708a000
GSNPSID = 0x4f54280a

Regdump after resume (not working):
GOTGCTL = 0x001c0001
GOTGINT = 0x00000000
GAHBCFG = 0x0000001f
GUSBCFG = 0x20402700
GRSTCTL = 0x80000000
GINTSTS = 0x0400003b
GINTMSK = 0xf1000806
GRXSTSR = 0x000f0002
GRXFSIZ = 0x00000306
GNPTXFSIZ = 0x01000306
GNPTXSTS = 0x07080100
GI2CCTL = 0x00000000
GPVNDCTL = 0x00000000
GGPIO = 0x00000000
GUID = 0x2708a000
GSNPSID = 0x4f54280a

So after the power off of USB, the DWC2 is unable to restore the
register properly. In a naive attempt, made this change:

--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -704,6 +704,8 @@ static int __maybe_unused dwc2_resume(struct device
*dev)
         }
         dwc2->phy_off_for_suspend = false;

+       dwc2_core_init(dwc2, true);
+
         if (dwc2->params.activate_stm_id_vb_detection) {
                 unsigned long flags;
                 u32 ggpio, gotgctl;

This improved the situation a little bit because the console becomes
available from suspend much faster, but USB is still not functional.

Best regards

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