linux-kernel - [PATCH 13/15] usb: dwc2: Add exit hibernation mode before removing drive

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Date:   Thu, 15 Apr 2021 09:41:04 +0400
From:   Artur Petrosyan <Arthur.Petrosyan@...opsys.com>
To:     Felipe Balbi <balbi@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Minas Harutyunyan <Minas.Harutyunyan@...opsys.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     John Youn <John.Youn@...opsys.com>,
        Artur Petrosyan <Arthur.Petrosyan@...opsys.com>
Subject: [PATCH 13/15] usb: dwc2: Add exit hibernation mode before removing drive

When dwc2 core is in hibernation mode loading
driver again causes driver fail. Because in
that mode registers are not accessible.

In order to exit from hibernation checking
dwc2 core power saving state in "dwc2_driver_remove()"
function. If core is in hibernation, then checking the
operational mode of the driver. To check whether dwc2 core
is operating in host mode or device mode there is one way
which is retrieving the backup value of "gotgctl" and compare
the "CurMod" value. If previously core entered hibernation
in host mode then the exit is performed for host if not then
exit is performed for device mode. The introduced checking
is because in hibernation state all registers are not
accessible.

Signed-off-by: Artur Petrosyan <Arthur.Petrosyan@...opsys.com>
---
 drivers/usb/dwc2/platform.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
index f8b819cfa80e..2ae4748ed5ec 100644
--- a/drivers/usb/dwc2/platform.c
+++ b/drivers/usb/dwc2/platform.c
@@ -316,8 +316,24 @@ static int dwc2_lowlevel_hw_init(struct dwc2_hsotg *hsotg)
 static int dwc2_driver_remove(struct platform_device *dev)
 {
 	struct dwc2_hsotg *hsotg = platform_get_drvdata(dev);
+	struct dwc2_gregs_backup *gr;
 	int ret = 0;

+	/* Exit Hibernation when driver is removed. */
+	if (hsotg->hibernated) {
+		if (gr->gotgctl & GOTGCTL_CURMODE_HOST) {
+			ret = dwc2_exit_hibernation(hsotg, 0, 0, 1);
+			if (ret)
+				dev_err(hsotg->dev,
+					"exit hibernation failed.\n");
+		} else {
+			ret = dwc2_exit_hibernation(hsotg, 0, 0, 0);
+			if (ret)
+				dev_err(hsotg->dev,
+					"exit hibernation failed.\n");
+		}
+	}
+
 	/* Exit Partial Power Down when driver is removed. */
 	if (hsotg->in_ppd) {
 		ret = dwc2_exit_partial_power_down(hsotg, 0, true);
-- 
2.25.1