[PATCH v2 3/3] usb: dwc3: xilinx: unwind ZynqMP platform init on probe failure and remove

[Radhey Shyam Pandey]

dwc3_xlnx_init_zynqmp() deasserts resets and initialises the USB3 PHY,
but nothing undoes that if a later probe step fails, and nothing undoes
it on remove either. The resets stay deasserted and the PHY stays
initialised while the clocks are disabled underneath them.

Add dwc3_xlnx_exit_zynqmp() and register it as the platform exit handler
once ZynqMP init has completed. Call it from the probe error path for
failures after init succeeded, and from remove(), which also serves as
the shutdown callback.

Fixes: 84770f028fab ("usb: dwc3: Add driver for Xilinx platforms")
Cc: stable at vger.kernel.org
Assisted-by: Claude:claude-opus-5
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey at amd.com>
---
Changes in v2:
- Reworked so the fix no longer depends on the platform-data cleanup.
  v1 registered the teardown as plat->exit in struct dwc3_xlnx_platdata,
  which is introduced by one of the cleanup patches; that made the fix
  unbackportable.  It now uses a pltfm_exit pointer alongside the
  existing pltfm_init in struct dwc3_xlnx, assigned by
  dwc3_xlnx_init_zynqmp() once init has succeeded.  The follow-up
  cleanup series folds both pointers into the platform data struct.
- Made dwc3_xlnx_exit_zynqmp() idempotent by returning early when
  usb_resets_released is clear, rather than guarding only the reset
  assertions.  phy_power_off() and phy_exit() decrement their counts
  unconditionally, so an unbalanced second call would underflow them.
- Rewrote the commit message to describe the bug rather than the
  implementation, since the callback it referred to no longer exists at
  this point in the series.
- Added Cc: stable.

 drivers/usb/dwc3/dwc3-xilinx.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/dwc3/dwc3-xilinx.c b/drivers/usb/dwc3/dwc3-xilinx.c
index d18d3e364381..31ac75b79709 100644
--- a/drivers/usb/dwc3/dwc3-xilinx.c
+++ b/drivers/usb/dwc3/dwc3-xilinx.c
@@ -47,6 +47,7 @@ struct dwc3_xlnx {
 	struct device			*dev;
 	void __iomem			*regs;
 	int				(*pltfm_init)(struct dwc3_xlnx *data);
+	void				(*pltfm_exit)(struct dwc3_xlnx *data);
 	struct phy			*usb3_phy;
 	struct reset_control		*usb_crst;
 	struct reset_control		*usb_hibrst;
@@ -113,6 +114,21 @@ static int dwc3_xlnx_init_versal(struct dwc3_xlnx *priv_data)
 	return 0;
 }
 
+static void dwc3_xlnx_exit_zynqmp(struct dwc3_xlnx *priv_data)
+{
+	if (!priv_data->usb_resets_released)
+		return;
+
+	phy_power_off(priv_data->usb3_phy);
+
+	reset_control_assert(priv_data->usb_hibrst);
+	reset_control_assert(priv_data->usb_crst);
+	reset_control_assert(priv_data->usb_apbrst);
+	priv_data->usb_resets_released = false;
+
+	phy_exit(priv_data->usb3_phy);
+}
+
 static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data)
 {
 	struct device		*dev = priv_data->dev;
@@ -230,6 +246,7 @@ static int dwc3_xlnx_init_zynqmp(struct dwc3_xlnx *priv_data)
 	dwc3_xlnx_set_coherency(priv_data, XLNX_USB_TRAFFIC_ROUTE_CONFIG);
 
 	priv_data->usb_resets_released = true;
+	priv_data->pltfm_exit = dwc3_xlnx_exit_zynqmp;
 
 	return 0;
 
@@ -326,11 +343,11 @@ static int dwc3_xlnx_probe(struct platform_device *pdev)
 
 	ret = dwc3_set_swnode(dev);
 	if (ret)
-		goto err_clk_put;
+		goto err_pltfm_exit;
 
 	ret = of_platform_populate(np, NULL, NULL, dev);
 	if (ret)
-		goto err_clk_put;
+		goto err_pltfm_exit;
 
 	pm_runtime_set_active(dev);
 	ret = devm_pm_runtime_enable(dev);
@@ -348,6 +365,10 @@ static int dwc3_xlnx_probe(struct platform_device *pdev)
 	of_platform_depopulate(dev);
 	pm_runtime_set_suspended(dev);
 
+err_pltfm_exit:
+	if (priv_data->pltfm_exit)
+		priv_data->pltfm_exit(priv_data);
+
 err_clk_put:
 	clk_bulk_disable_unprepare(priv_data->num_clocks, priv_data->clks);
 
@@ -361,6 +382,9 @@ static void dwc3_xlnx_remove(struct platform_device *pdev)
 
 	of_platform_depopulate(dev);
 
+	if (priv_data->pltfm_exit)
+		priv_data->pltfm_exit(priv_data);
+
 	clk_bulk_disable_unprepare(priv_data->num_clocks, priv_data->clks);
 	priv_data->num_clocks = 0;
 
-- 
2.43.0