linux-kernel - [PATCH v4 1/4] usb: dwc3-am62: fix module unload/reload behavior

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Message-Id: <20240227-for-v6-9-am62-usb-errata-3-0-v4-1-0ada8ddb0767@kernel.org>
Date: Tue, 27 Feb 2024 11:23:48 +0200
From: Roger Quadros <rogerq@...nel.org>
To: Thinh Nguyen <Thinh.Nguyen@...opsys.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
 Rob Herring <robh+dt@...nel.org>, 
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
 Conor Dooley <conor+dt@...nel.org>
Cc: nm@...com, r-gunasekaran@...com, afd@...com, b-liu@...com, srk@...com, 
 francesco@...cini.it, linux-usb@...r.kernel.org, 
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org, 
 Roger Quadros <rogerq@...nel.org>, stable@...r.kernel.org
Subject: [PATCH v4 1/4] usb: dwc3-am62: fix module unload/reload behavior

As runtime PM is enabled, the module can be runtime
suspended when .remove() is called.

Do a pm_runtime_get_sync() to make sure module is active
before doing any register operations.

Doing a pm_runtime_put_sync() should disable the refclk
so no need to disable it again.

Fixes the below warning at module removel.

[   39.705310] ------------[ cut here ]------------
[   39.710004] clk:162:3 already disabled
[   39.713941] WARNING: CPU: 0 PID: 921 at drivers/clk/clk.c:1090 clk_core_disable+0xb0/0xb8

We called of_platform_populate() in .probe() so call the
cleanup function of_platform_depopulate() in .remove().
Get rid of the now unnnecessary dwc3_ti_remove_core().
Without this, module re-load doesn't work properly.

Fixes: e8784c0aec03 ("drivers: usb: dwc3: Add AM62 USB wrapper driver")
Cc:  <stable@...r.kernel.org> # v5.19+
Signed-off-by: Roger Quadros <rogerq@...nel.org>
---
Changelog:
v4:
- added Fixes and Cc stable.
- added of_platform_depopulate() changes here.
- drop wakeup disable code.
v3: no change
v2: no change
---
 drivers/usb/dwc3/dwc3-am62.c | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/dwc3/dwc3-am62.c b/drivers/usb/dwc3/dwc3-am62.c
index 90a587bc29b7..f85603b7f7c5 100644
--- a/drivers/usb/dwc3/dwc3-am62.c
+++ b/drivers/usb/dwc3/dwc3-am62.c
@@ -267,21 +267,14 @@ static int dwc3_ti_probe(struct platform_device *pdev)
 	return ret;
 }
 
-static int dwc3_ti_remove_core(struct device *dev, void *c)
-{
-	struct platform_device *pdev = to_platform_device(dev);
-
-	platform_device_unregister(pdev);
-	return 0;
-}
-
 static void dwc3_ti_remove(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct dwc3_am62 *am62 = platform_get_drvdata(pdev);
 	u32 reg;
 
-	device_for_each_child(dev, NULL, dwc3_ti_remove_core);
+	pm_runtime_get_sync(dev);
+	of_platform_depopulate(dev);
 
 	/* Clear mode valid bit */
 	reg = dwc3_ti_readl(am62, USBSS_MODE_CONTROL);
@@ -289,7 +282,6 @@ static void dwc3_ti_remove(struct platform_device *pdev)
 	dwc3_ti_writel(am62, USBSS_MODE_CONTROL, reg);
 
 	pm_runtime_put_sync(dev);
-	clk_disable_unprepare(am62->usb2_refclk);
 	pm_runtime_disable(dev);
 	pm_runtime_set_suspended(dev);
 }

-- 
2.34.1