Hi William,
On 9/10/2023 8:31 PM, 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.
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);
In case DWC3 is runtime suspended, then we will avoid the
dwc3_resume_common() call, but the current flow would also set the RPM
state to RPM_ACTIVE. (from pm_runtime_set_active()) In this case, what
happens if there is a pm_runtime_get/resume on the DWC3 device?
I think it would avoid calling rpm_resume() since the RPM state is
already active, so we wouldn't be calling dwc3_runtime_resume(). Do you
want to also extend the RPM suspended check to cover if we need to force
PM runtime state back to active?
Thanks
Wesley Cheng
