Re: [PATCH v2] usb: dwc3: core: Avoid resume dwc3 if already suspended in pm resume

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Hi Thinh,

On 2023/9/12 8:08, Thinh Nguyen wrote:
Hi,

On Mon, Sep 11, 2023, William Wu wrote:
If we enable PM runtime auto suspend for dwc3 on rockchip
platforms (e.g. RK3562), it allows the dwc3 controller to
enter runtime suspend if usb cable detached and power off
the power domain of the controller. When system resume, if
the dwc3 already in runtime suspended, it Shouldn't access
the dwc3 registers in dwc3_resume() because its power domain
maybe power off.

Test on RK3562 tablet, this patch can help to avoid kernel
panic when accessing the dwc3 registers in dwc3_resume() if
the dwc3 is in runtime suspended and it's power domain is
power off.
The controller should be woken up before this step. Can you provide more
detail on what led to this?

Yes, the power domain of the usb controller will be enabled by the framework of  the pm generic domain before dwc3 resume if the system enter suspend and exit suspend normally. However, in my test case,if the system fail to enter suspend because of some devices's problem, and then goto recovery process, the power domain of the usb controller will not be enable before dwc3 resume.

e.g. some questions:
Who handles the waking up of the controller? Is it the phy driver? Is
the phy driver not detecting a resume? Or did the resume fail? Does this
occur consistently?

Thanks,
Thinh

This issue occurs occasionally on RK3562 EVB with Type-C USB, and enable autosuspend for dwc3 controller.

Here is the test steps:

1. Power on the RK3562 EVB and the Type-C USB interface is in unconnected state.

2. Makesure the dwc3 controller enter runtime suspend, and its power domain is disabled.

3. Do system suspend/resume stress test.

4. The issue occurs occasionally  with the following log:

[  251.681091][ T4331] PM: suspend entry (deep)
[  251.778975][ T4331] Filesystems sync: 0.097 seconds
[  251.779025][ T4331] Freezing user space processes ... (elapsed 0.005 seconds) done.
[  251.784819][ T4331] OOM killer disabled.
[  251.784851][ T4331] Freezing remaining freezable tasks ... (elapsed 0.004 seconds) done. [  251.792719][  T503] [SKWIFI DBG] skw_suspend: WoW: enabled, skw flags: 0x302 [  251.803701][ T4331] PM: dpm_run_callback(): platform_pm_suspend.cfi_jt+0x0/0x8 returns -16
[  251.803779][   T75] PM: PM: Pending Wakeup Sources: alarmtimer.0.auto
[  251.803789][ T4331] PM: Device alarmtimer.0.a
[  251.803928][ T4331] PM: Some devices failed to suspend, or early wake event detected
[  251.804141][   T75] [SKWIFI DBG] skw_resume: skw flags: 0x300
[  251.804715][    C2] SError Interrupt on CPU2, code 0xbf000000 -- SError
[  251.804725][    C2] CPU: 2 PID: 4331 Comm: binder:251_4 Tainted: G        WC  E 5.10.157-android13-4-00006-g73f337804fbc-ab9881769 #1 [  251.804732][    C2] Hardware name: Rockchip RK3562 RK817 TABLET LP4 Board (DT)
[  251.804738][    C2] pstate: 80400005 (Nzcv daif +PAN -UAO -TCO BTYPE=--)
[  251.804743][    C2] pc : el1_abort+0x40/0x68
[  251.804748][    C2] lr : el1_abort+0x28/0x68

......

[  251.804965][    C2] Kernel panic - not syncing: Asynchronous SError Interrupt [  251.804974][    C2] CPU: 2 PID: 4331 Comm: binder:251_4 Tainted: G        WC  E 5.10.157-android13-4-00006-g73f337804fbc-ab9881769 #1 [  251.804980][    C2] Hardware name: Rockchip RK3562 RK817 TABLET LP4 Board (DT)
[  251.804984][    C2] Call trace:
[  251.804990][    C2]  dump_backtrace.cfi_jt+0x0/0x8
[  251.804995][    C2]  dump_stack_lvl+0xc0/0x13c
[  251.805000][    C2]  panic+0x174/0x468
[  251.805006][    C2]  arm64_serror_panic+0x1b0/0x200
[  251.805010][    C2]  do_serror+0x184/0x1e4
[  251.805016][    C2]  el1_error+0x94/0x118
[  251.805020][    C2]  el1_abort+0x40/0x68
[  251.805026][    C2]  el1_sync_handler+0x58/0x88
[  251.805031][    C2]  el1_sync+0x8c/0x140
[  251.805035][    C2]  dwc3_readl+0x30/0x1a0
[  251.805040][    C2]  dwc3_phy_setup+0x38/0x510
[  251.805045][    C2]  dwc3_core_init+0x68/0xcd4
[  251.805051][    C2]  dwc3_core_init_for_resume+0x10c/0x25c
[  251.805056][    C2]  dwc3_resume_common+0x44/0x3d0
[  251.805061][    C2]  dwc3_resume+0x5c/0xb8
[  251.805067][    C2]  dpm_run_callback+0x70/0x488
[  251.805071][    C2]  device_resume+0x250/0x2f8
[  251.805077][    C2]  dpm_resume+0x258/0x9dc
[  251.805082][    C2]  suspend_devices_and_enter+0x850/0xcac

In this case, during suspend process, because the device alarmtimer failed to suspend, it break the system suspend in the funciton suspend_devices_and_enter(), and goto platform_recover() directly without enable the power domain of the controller, then trigger the Kernel panic in dwc3_resume().


For a comparison, in the normal case, if the system enter suspend normally, and after the system wakeup, the power domain of the controller will be enable by the framework of  the pm generic domain before dwc3 resume.

The function call stack like this:

suspend_devices_and_enter -->

    suspend_enter -->

         dpm_resume_noirq --> dpm_noirq_resume_devices --> device_resume_noirq --> genpd_resume_noirq --> rockchip_pd_power (enable the power domain of the controller)

    dpm_resume_end -->

         dpm_resume --> device_resume --> dpm_run_callback --> dwc3_resume (access the controller safely)

         dpm_complete --> genpd_complete --> genpd_queue_power_off_work

suspend_finish --> suspend_thaw_processes --> genpd_power_off_work_fn --> (diable the power domain of the controller to maintain the original runtime  suspend state)


Thanks,

William


Kernel panic - not syncing: Asynchronous SError Interrupt
Hardware name: Rockchip RK3562 RK817 TABLET LP4 Board (DT)
Call trace:
dump_backtrace.cfi_jt+0x0/0x8
   dump_stack_lvl+0xc0/0x13c
   panic+0x174/0x468
   arm64_serror_panic+0x1b0/0x200
   do_serror+0x184/0x1e4
   el1_error+0x94/0x118
   el1_abort+0x40/0x68
   el1_sync_handler+0x58/0x88
   el1_sync+0x8c/0x140
   dwc3_readl+0x30/0x1a0
   dwc3_phy_setup+0x38/0x510
   dwc3_core_init+0x68/0xcd4
   dwc3_core_init_for_resume+0x10c/0x25c
   dwc3_resume_common+0x44/0x3d0
   dwc3_resume+0x5c/0xb8
   dpm_run_callback+0x70/0x488
   device_resume+0x250/0x2f8
   dpm_resume+0x258/0x9dc

Signed-off-by: William Wu <william.wu@xxxxxxxxxxxxxx>
---
Changes in v2:
- Remove Change-Id.

  drivers/usb/dwc3/core.c | 8 +++++---
  1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 9c6bf054f15d..8274a44f2d6a 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -2185,9 +2185,11 @@ static int dwc3_resume(struct device *dev)
pinctrl_pm_select_default_state(dev); - ret = dwc3_resume_common(dwc, PMSG_RESUME);
-	if (ret)
-		return ret;
+	if (!pm_runtime_suspended(dwc->dev)) {
+		ret = dwc3_resume_common(dwc, PMSG_RESUME);
+		if (ret)
+			return ret;
+	}
pm_runtime_disable(dev);
  	pm_runtime_set_active(dev);
--
2.17.1




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