Re: [RFC PATCH 2/2] usb: dwc3: Support 'snps,gadget-keep-connect-sys-sleep' feature

Roger Quadros
2023-03-21T10:20:19Z

Hi Thinh,

On 20/03/2023 20:52, Thinh Nguyen wrote:
> Hi,
>
> On Mon, Mar 20, 2023, Roger Quadros wrote:
>> Implement 'snps,gadget-keep-connect-sys-sleep' property.
>>
>> Do not stop the gadget controller and disconnect if this
>> property is present and we are connected to a USB Host.
>>
>> Prevent System sleep if Gadget is not in USB suspend.
>>
>> Signed-off-by: Roger Quadros <rogerq@kernel.org>
>> ---
>> drivers/usb/dwc3/core.c | 25 +++++++++++++++++++------
>> drivers/usb/dwc3/core.h | 2 ++
>> drivers/usb/dwc3/gadget.c | 25 +++++++++++++++++++++++--
>> 3 files changed, 44 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
>> index 476b63618511..a47bbaa27302 100644
>> --- a/drivers/usb/dwc3/core.c
>> +++ b/drivers/usb/dwc3/core.c
>> @@ -1575,6 +1575,9 @@ static void dwc3_get_properties(struct dwc3 *dwc)
>> dwc->dis_split_quirk = device_property_read_bool(dev,
>> "snps,dis-split-quirk");
>>
>> + dwc->gadget_keep_connect_sys_sleep = device_property_read_bool(dev,
>> + "snps,gadget-keep-connect-sys-sleep");
>> +
>> dwc->lpm_nyet_threshold = lpm_nyet_threshold;
>> dwc->tx_de_emphasis = tx_de_emphasis;
>>
>> @@ -2027,14 +2030,20 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>> {
>> unsigned long flags;
>> u32 reg;
>> + int ret;
>>
>> switch (dwc->current_dr_role) {
>> case DWC3_GCTL_PRTCAP_DEVICE:
>> if (pm_runtime_suspended(dwc->dev))
>> break;
>> - dwc3_gadget_suspend(dwc);
>> + ret = dwc3_gadget_suspend(dwc);
>> + if (ret) {
>> + dev_err(dwc->dev, "gadget not suspended: %d\n", ret);
>> + return ret;
>> + }
>> synchronize_irq(dwc->irq_gadget);
>> - dwc3_core_exit(dwc);
>> + if(!dwc->gadget_keep_connect_sys_sleep)
>> + dwc3_core_exit(dwc);
>> break;
>> case DWC3_GCTL_PRTCAP_HOST:
>> if (!PMSG_IS_AUTO(msg) && !device_may_wakeup(dwc->dev)) {
>> @@ -2088,11 +2097,15 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
>>
>> switch (dwc->current_dr_role) {
>> case DWC3_GCTL_PRTCAP_DEVICE:
>> - ret = dwc3_core_init_for_resume(dwc);
>> - if (ret)
>> - return ret;
>> + if (!dwc->gadget_keep_connect_sys_sleep)
>> + {
>> + ret = dwc3_core_init_for_resume(dwc);
>> + if (ret)
>> + return ret;
>> +
>> + dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_DEVICE);
>> + }
>>
>> - dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_DEVICE);
>> dwc3_gadget_resume(dwc);
>> break;
>> case DWC3_GCTL_PRTCAP_HOST:
>> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
>> index 582ebd9cf9c2..f84bac815bed 100644
>> --- a/drivers/usb/dwc3/core.h
>> +++ b/drivers/usb/dwc3/core.h
>> @@ -1328,6 +1328,8 @@ struct dwc3 {
>> unsigned dis_split_quirk:1;
>> unsigned async_callbacks:1;
>>
>> + unsigned gadget_keep_connect_sys_sleep:1;
>> +
>> u16 imod_interval;
>>
>> int max_cfg_eps;
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index 3c63fa97a680..8062e44f63f6 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -4572,12 +4572,23 @@ void dwc3_gadget_exit(struct dwc3 *dwc)
>> int dwc3_gadget_suspend(struct dwc3 *dwc)
>> {
>> unsigned long flags;
>> + int link_state;
>>
>> if (!dwc->gadget_driver)
>> return 0;
>>
>> - dwc3_gadget_run_stop(dwc, false, false);
>> + if (dwc->gadget_keep_connect_sys_sleep && dwc->connected) {
>> + link_state = dwc3_gadget_get_link_state(dwc);
>> + /* Prevent PM Sleep if not in U3/L2 */
>> + if (link_state != DWC3_LINK_STATE_U3)
>> + return -EBUSY;
>> +
>> + /* don't stop/disconnect */
>> + dwc3_gadget_disable_irq(dwc);
>
> We shouldn't disable event interrupt here. What will happen if the

Due to some reason, if I don't disable the event interrupts here then
after USB resume the USB controller is malfunctioning.
It no longer responds to any requests from Host.

> device is disconnected and reconnect to the host while the device is
> still in system suspend? The host would not be able to communicate with
> the device then.

In the TI platform, The system is woken up on any VBUS/linestate change
and in dwc3_gadget_resume we enable the events again and check for pending
events. Is it pointless to check for pending events there?

cheers,
-roger

>
> BR,
> Thinh
>
>> + return 0;
>> + }
>>
>> + dwc3_gadget_run_stop(dwc, false, false);
>> spin_lock_irqsave(&dwc->lock, flags);
>> dwc3_disconnect_gadget(dwc);
>> __dwc3_gadget_stop(dwc);
>> @@ -4588,11 +4599,21 @@ int dwc3_gadget_suspend(struct dwc3 *dwc)
>>
>> int dwc3_gadget_resume(struct dwc3 *dwc)
>> {
>> - int ret;
>> + int ret;
>> + irqreturn_t irq_t;
>>
>> if (!dwc->gadget_driver || !dwc->softconnect)
>> return 0;
>>
>> + if (dwc->gadget_keep_connect_sys_sleep && dwc->connected) {
>> + dwc3_gadget_enable_irq(dwc);
>> + /* check pending events */
>> + irq_t = dwc3_check_event_buf(dwc->ev_buf);
>> + if (irq_t == IRQ_WAKE_THREAD)
>> + dwc3_process_event_buf(dwc->ev_buf);
>> + return 0;
>> + }
>> +
>> ret = __dwc3_gadget_start(dwc);
>> if (ret < 0)
>> goto err0;
>> --
>> 2.34.1