linux-kernel - [PATCH 1/2] usb: host: xhci-plat: suspend and resume clocks

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Message-Id: <1660170455-15781-2-git-send-email-justinpopo6@gmail.com>
Date:   Wed, 10 Aug 2022 15:27:34 -0700
From:   justinpopo6@...il.com
To:     mathias.nyman@...el.com, gregkh@...uxfoundation.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     f.fainelli@...il.com, Justin Chen <justinpopo6@...il.com>
Subject: [PATCH 1/2] usb: host: xhci-plat: suspend and resume clocks

From: Justin Chen <justinpopo6@...il.com>

Introduce XHCI_SUSPEND_RESUME_CLKS quirk as a means to suspend and resume
clocks if the hardware is capable of doing so. We assume that clocks will
be needed if the device may wake.

Signed-off-by: Justin Chen <justinpopo6@...il.com>
---
 drivers/usb/host/xhci-plat.c | 16 +++++++++++++++-
 drivers/usb/host/xhci.h      |  1 +
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 0448558..a68b2b0 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -432,7 +432,16 @@ static int __maybe_unused xhci_plat_suspend(struct device *dev)
 	 * xhci_suspend() needs `do_wakeup` to know whether host is allowed
 	 * to do wakeup during suspend.
 	 */
-	return xhci_suspend(xhci, device_may_wakeup(dev));
+	ret = xhci_suspend(xhci, device_may_wakeup(dev));
+	if (ret)
+		return ret;
+
+	if (!device_may_wakeup(dev) && (xhci->quirks & XHCI_SUSPEND_RESUME_CLKS)) {
+		clk_disable_unprepare(xhci->clk);
+		clk_disable_unprepare(xhci->reg_clk);
+	}
+
+	return 0;
 }
 
 static int __maybe_unused xhci_plat_resume(struct device *dev)
@@ -441,6 +450,11 @@ static int __maybe_unused xhci_plat_resume(struct device *dev)
 	struct xhci_hcd	*xhci = hcd_to_xhci(hcd);
 	int ret;
 
+	if (!device_may_wakeup(dev) && (xhci->quirks & XHCI_SUSPEND_RESUME_CLKS)) {
+		clk_prepare_enable(xhci->clk);
+		clk_prepare_enable(xhci->reg_clk);
+	}
+
 	ret = xhci_priv_resume_quirk(hcd);
 	if (ret)
 		return ret;
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 1960b47..182d1d4 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1899,6 +1899,7 @@ struct xhci_hcd {
 #define XHCI_NO_SOFT_RETRY	BIT_ULL(40)
 #define XHCI_BROKEN_D3COLD	BIT_ULL(41)
 #define XHCI_EP_CTX_BROKEN_DCS	BIT_ULL(42)
+#define XHCI_SUSPEND_RESUME_CLKS	BIT_ULL(43)
 
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;
-- 
2.7.4