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

Roger Quadros
2023-03-20T09:35:11Z

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);
+ 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