| Message ID | 20240903094156.6516-1-tomas.marek@elrest.cz |
|---|---|
| State | Superseded |
| Headers | show |
| Series | usb: dwc2: drd: fix clock gating on USB role switch | expand |
On 9/3/24 12:41 PM, Tomas Marek wrote: > The dwc2_handle_usb_suspend_intr() function disables gadget clocks in USB > peripheral mode when no other power-down mode is available (introduced by > commit 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")). > However, the dwc2_drd_role_sw_set() USB role update handler attempts to > read DWC2 registers if the USB role has changed while the USB is in suspend > mode (when the clocks are gated). This causes the system to hang. > > Release gadget clocks before handling the USB role update. > > Fixes: 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.") > > Signed-off-by: Tomas Marek <tomas.marek@elrest.cz> > --- > drivers/usb/dwc2/drd.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/usb/dwc2/drd.c b/drivers/usb/dwc2/drd.c > index a8605b02115b..ccb33cd1f04b 100644 > --- a/drivers/usb/dwc2/drd.c > +++ b/drivers/usb/dwc2/drd.c > @@ -127,6 +127,18 @@ static int dwc2_drd_role_sw_set(struct usb_role_switch *sw, enum usb_role role) > role = USB_ROLE_DEVICE; > } > > +#if IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) || \ > + IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE) > + if (dwc2_is_device_mode(hsotg)) { Why not avoid #ifdef by doing e.g.: if ((IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) || \ IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE) && dwc2_is_device_mode(hsotg)) { > + if (hsotg->lx_state == DWC2_L2) { > + if (hsotg->params.power_down == > + DWC2_POWER_DOWN_PARAM_NONE && hsotg->bus_suspended && > + !hsotg->params.no_clock_gating) Well, these *if*s are mergeable too... :-) > + dwc2_gadget_exit_clock_gating(hsotg, 0); > + } > + } > +#endif > + [...] MBR, Sergey
Hi Sergey, thank you for your review. On Tue, Sep 03, 2024 at 04:20:26PM +0300, Sergey Shtylyov wrote: > On 9/3/24 12:41 PM, Tomas Marek wrote: > > > The dwc2_handle_usb_suspend_intr() function disables gadget clocks in USB > > peripheral mode when no other power-down mode is available (introduced by > > commit 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")). > > However, the dwc2_drd_role_sw_set() USB role update handler attempts to > > read DWC2 registers if the USB role has changed while the USB is in suspend > > mode (when the clocks are gated). This causes the system to hang. > > > > Release gadget clocks before handling the USB role update. > > > > Fixes: 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.") > > > > Signed-off-by: Tomas Marek <tomas.marek@elrest.cz> > > --- > > drivers/usb/dwc2/drd.c | 12 ++++++++++++ > > 1 file changed, 12 insertions(+) > > > > diff --git a/drivers/usb/dwc2/drd.c b/drivers/usb/dwc2/drd.c > > index a8605b02115b..ccb33cd1f04b 100644 > > --- a/drivers/usb/dwc2/drd.c > > +++ b/drivers/usb/dwc2/drd.c > > @@ -127,6 +127,18 @@ static int dwc2_drd_role_sw_set(struct usb_role_switch *sw, enum usb_role role) > > role = USB_ROLE_DEVICE; > > } > > > > +#if IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) || \ > > + IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE) > > + if (dwc2_is_device_mode(hsotg)) { > > Why not avoid #ifdef by doing e.g.: > > if ((IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) || \ > IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE) && > dwc2_is_device_mode(hsotg)) { > > > + if (hsotg->lx_state == DWC2_L2) { > > + if (hsotg->params.power_down == > > + DWC2_POWER_DOWN_PARAM_NONE && hsotg->bus_suspended && > > + !hsotg->params.no_clock_gating) > > Well, these *if*s are mergeable too... :-) > OK, why not. In the end all conditions could be merged into one if statement like: if ((IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) || IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE)) && dwc2_is_device_mode(hsotg) && hsotg->lx_state == DWC2_L2 && hsotg->params.power_down == DWC2_POWER_DOWN_PARAM_NONE && hsotg->bus_suspended && !hsotg->params.no_clock_gating) dwc2_gadget_exit_clock_gating(hsotg, 0); I’ll submit a new patch version with this modification. Best regards Tomas > > + dwc2_gadget_exit_clock_gating(hsotg, 0); > > + } > > + } > > +#endif > > + > [...] > > MBR, Sergey
diff --git a/drivers/usb/dwc2/drd.c b/drivers/usb/dwc2/drd.c index a8605b02115b..ccb33cd1f04b 100644 --- a/drivers/usb/dwc2/drd.c +++ b/drivers/usb/dwc2/drd.c @@ -127,6 +127,18 @@ static int dwc2_drd_role_sw_set(struct usb_role_switch *sw, enum usb_role role) role = USB_ROLE_DEVICE; } +#if IS_ENABLED(CONFIG_USB_DWC2_PERIPHERAL) || \ + IS_ENABLED(CONFIG_USB_DWC2_DUAL_ROLE) + if (dwc2_is_device_mode(hsotg)) { + if (hsotg->lx_state == DWC2_L2) { + if (hsotg->params.power_down == + DWC2_POWER_DOWN_PARAM_NONE && hsotg->bus_suspended && + !hsotg->params.no_clock_gating) + dwc2_gadget_exit_clock_gating(hsotg, 0); + } + } +#endif + if (role == USB_ROLE_HOST) { already = dwc2_ovr_avalid(hsotg, true); } else if (role == USB_ROLE_DEVICE) {
The dwc2_handle_usb_suspend_intr() function disables gadget clocks in USB peripheral mode when no other power-down mode is available (introduced by commit 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.")). However, the dwc2_drd_role_sw_set() USB role update handler attempts to read DWC2 registers if the USB role has changed while the USB is in suspend mode (when the clocks are gated). This causes the system to hang. Release gadget clocks before handling the USB role update. Fixes: 0112b7ce68ea ("usb: dwc2: Update dwc2_handle_usb_suspend_intr function.") Signed-off-by: Tomas Marek <tomas.marek@elrest.cz> --- drivers/usb/dwc2/drd.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)