[PATCH v3] usb: dwc3: core: Fix system suspend on TI AM62 platforms

Roger Quadros
2024-10-11T10:53:41Z

Since commit 6d735722063a ("usb: dwc3: core: Prevent phy suspend during init"),
system suspend is broken on AM62 TI platforms.

Before that commit, both DWC3_GUSB3PIPECTL_SUSPHY and DWC3_GUSB2PHYCFG_SUSPHY
bits (hence forth called 2 SUSPHY bits) were being set during core
initialization and even during core re-initialization after a system
suspend/resume.

These bits are required to be set for system suspend/resume to work correctly
on AM62 platforms.

Since that commit, the 2 SUSPHY bits are not set for DEVICE/OTG mode if gadget
driver is not loaded and started.
For Host mode, the 2 SUSPHY bits are set before the first system suspend but
get cleared at system resume during core re-init and are never set again.

This patch resovles these two issues by ensuring the 2 SUSPHY bits are set
before system suspend and restored to the original state during system resume.

Cc: stable@vger.kernel.org # v6.9+
Fixes: 6d735722063a ("usb: dwc3: core: Prevent phy suspend during init")
Link: https://lore.kernel.org/all/1519dbe7-73b6-4afc-bfe3-23f4f75d772f@kernel.org/
Signed-off-by: Roger Quadros <rogerq@kernel.org>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
---
Changes in v3:
- Fix single line comment style
- add DWC3_GUSB3PIPECTL_SUSPHY to documentation of susphy_state
- Added Acked-by tag
- Link to v2: https://lore.kernel.org/r/20241009-am62-lpm-usb-v2-1-da26c0cd2b1e@kernel.org

Changes in v2:
- Fix comment style
- Use both USB3 and USB2 SUSPHY bits to determine susphy_state during system suspend/resume.
- Restore SUSPHY bits at system resume regardless if it was set or cleared before system suspend.
- Link to v1: https://lore.kernel.org/r/20241001-am62-lpm-usb-v1-1-9916b71165f7@kernel.org
---
drivers/usb/dwc3/core.c | 19 +++++++++++++++++++
drivers/usb/dwc3/core.h | 3 +++
2 files changed, 22 insertions(+)

diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 9eb085f359ce..ca77f0b186c4 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -2336,6 +2336,11 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
u32 reg;
int i;

+ dwc->susphy_state = (dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0)) &
+ DWC3_GUSB2PHYCFG_SUSPHY) ||
+ (dwc3_readl(dwc->regs, DWC3_GUSB3PIPECTL(0)) &
+ DWC3_GUSB3PIPECTL_SUSPHY);
+
switch (dwc->current_dr_role) {
case DWC3_GCTL_PRTCAP_DEVICE:
if (pm_runtime_suspended(dwc->dev))
@@ -2387,6 +2392,15 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
break;
}

+ if (!PMSG_IS_AUTO(msg)) {
+ /*
+ * TI AM62 platform requires SUSPHY to be
+ * enabled for system suspend to work.
+ */
+ if (!dwc->susphy_state)
+ dwc3_enable_susphy(dwc, true);
+ }
+
return 0;
}

@@ -2454,6 +2468,11 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
break;
}

+ if (!PMSG_IS_AUTO(msg)) {
+ /* restore SUSPHY state to that before system suspend. */
+ dwc3_enable_susphy(dwc, dwc->susphy_state);
+ }
+
return 0;
}

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index c71240e8f7c7..31de4b57ae7c 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -1150,6 +1150,8 @@ struct dwc3_scratchpad_array {
* @sys_wakeup: set if the device may do system wakeup.
* @wakeup_configured: set if the device is configured for remote wakeup.
* @suspended: set to track suspend event due to U3/L2.
+ * @susphy_state: state of DWC3_GUSB2PHYCFG_SUSPHY + DWC3_GUSB3PIPECTL_SUSPHY
+ * before PM suspend.
* @imod_interval: set the interrupt moderation interval in 250ns
* increments or 0 to disable.
* @max_cfg_eps: current max number of IN eps used across all USB configs.
@@ -1382,6 +1384,7 @@ struct dwc3 {
unsigned sys_wakeup:1;
unsigned wakeup_configured:1;
unsigned suspended:1;
+ unsigned susphy_state:1;

u16 imod_interval;

---
base-commit: 9852d85ec9d492ebef56dc5f229416c925758edc
change-id: 20240923-am62-lpm-usb-f420917bd707

Best regards,
--
Roger Quadros <rogerq@kernel.org>