linux-kernel - [PATCH v2 10/12] usb: dwc2: Add clock gating entering flow by system suspend

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Date:   Tue, 13 Apr 2021 11:37:15 +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 v2 10/12] usb: dwc2: Add clock gating entering flow by system suspend

If not hibernation nor partial power down are supported,
clock gating is used to save power.

Adds a new flow of entering clock gating when PC is
suspended.

Signed-off-by: Artur Petrosyan <Arthur.Petrosyan@...opsys.com>
---
 Changes in v2:
 - None

 drivers/usb/dwc2/hcd.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index 31d6a1b87228..09dcd37b9ef8 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -4372,6 +4372,15 @@ static int _dwc2_hcd_suspend(struct usb_hcd *hcd)
 		break;
 	case DWC2_POWER_DOWN_PARAM_HIBERNATION:
 	case DWC2_POWER_DOWN_PARAM_NONE:
+		/*
+		 * If not hibernation nor partial power down are supported,
+		 * clock gating is used to save power.
+		 */
+		dwc2_host_enter_clock_gating(hsotg);
+
+		/* After entering suspend, hardware is not accessible */
+		clear_bit(HCD_FLAG_HW_ACCESSIBLE, &hcd->flags);
+		break;
 	default:
 		goto skip_power_saving;
 	}
-- 
2.25.1