linux-kernel - [PATCH 2/4] usb: host: ehci-platform: Call reset assert/deassert on suspend/resume

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Message-ID: <20251106143625.3050119-3-claudiu.beznea.uj@bp.renesas.com>
Date: Thu,  6 Nov 2025 16:36:23 +0200
From: Claudiu <claudiu.beznea@...on.dev>
To: stern@...land.harvard.edu,
	gregkh@...uxfoundation.org,
	p.zabel@...gutronix.de,
	yoshihiro.shimoda.uh@...esas.com,
	prabhakar.mahadev-lad.rj@...renesas.com,
	kuninori.morimoto.gx@...esas.com,
	geert+renesas@...der.be
Cc: claudiu.beznea@...on.dev,
	linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: [PATCH 2/4] usb: host: ehci-platform: Call reset assert/deassert on suspend/resume

From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

The Renesas RZ/G3S SoC supports a power-saving mode in which power to most
of the SoC components is turned off, including the USB blocks. On the
resume path, the reset signal must be de-asserted before applying any
settings to the USB registers. To handle this properly, call
reset_control_assert() and reset_control_deassert() during suspend and
resume, respectively.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
---
 drivers/usb/host/ehci-platform.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/host/ehci-platform.c b/drivers/usb/host/ehci-platform.c
index 57d5a7ddac5f..f61f095cedab 100644
--- a/drivers/usb/host/ehci-platform.c
+++ b/drivers/usb/host/ehci-platform.c
@@ -454,6 +454,17 @@ static int __maybe_unused ehci_platform_suspend(struct device *dev)
 	if (pdata->power_suspend)
 		pdata->power_suspend(pdev);
 
+	ret = reset_control_assert(priv->rsts);
+	if (ret) {
+		if (pdata->power_on)
+			pdata->power_on(pdev);
+
+		ehci_resume(hcd, false);
+
+		if (priv->quirk_poll)
+			quirk_poll_init(priv);
+	}
+
 	return ret;
 }
 
@@ -464,11 +475,18 @@ static int __maybe_unused ehci_platform_resume(struct device *dev)
 	struct platform_device *pdev = to_platform_device(dev);
 	struct ehci_platform_priv *priv = hcd_to_ehci_priv(hcd);
 	struct device *companion_dev;
+	int err;
+
+	err = reset_control_deassert(priv->rsts);
+	if (err)
+		return err;
 
 	if (pdata->power_on) {
-		int err = pdata->power_on(pdev);
-		if (err < 0)
+		err = pdata->power_on(pdev);
+		if (err < 0) {
+			reset_control_assert(priv->rsts);
 			return err;
+		}
 	}
 
 	companion_dev = usb_of_get_companion_dev(hcd->self.controller);
-- 
2.43.0