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From:   Martin Blumenstingl <martin.blumenstingl@googlemail.com>
To:     linux-usb@vger.kernel.org, hminas@synopsys.com,
        gregkh@linuxfoundation.org
Cc:     linux-kernel@vger.kernel.org, linux-amlogic@lists.infradead.org,
        Arthur.Petrosyan@synopsys.com, christianshewitt@gmail.com,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
        stable@vger.kernel.org
Subject: [PATCH 1/1] usb: dwc2: disable power_down on Amlogic devices
Date:   Sun,  9 Dec 2018 20:01:29 +0100
Message-Id: <20181209190129.11870-2-martin.blumenstingl@googlemail.com>
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Disable power_down by setting the parameter to
DWC2_POWER_DOWN_PARAM_NONE. This fixes a problem on various Amlogic
Meson SoCs where USB devices are only recognized when plugged in before
booting Linux. A hot-plugged USB device was not detected even though the
device got power (my USB thumb drive for example has an LED which lit
up).

A similar fix was implemented for Rockchip SoCs in commit c216765d3a1def
("usb: dwc2: disable power_down on rockchip devices"). That commit
suggests that a change in the dwc2 driver is the cause because the
default value for the "hibernate" parameter (which then got renamed to
"power_down" to support other modes) was changed in the v4.17 merge
window with:
commit 6d23ee9caa6790 ("Merge tag 'usb-for-v4.17' of git://git.kernel.org/pub/scm/linux/kernel/git/balbi/usb into usb-testing").

Cc: <stable@vger.kernel.org> # 4.19
Suggested-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
 drivers/usb/dwc2/params.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/dwc2/params.c b/drivers/usb/dwc2/params.c
index 7c1b6938f212..38c813b1d203 100644
--- a/drivers/usb/dwc2/params.c
+++ b/drivers/usb/dwc2/params.c
@@ -111,6 +111,7 @@ static void dwc2_set_amlogic_params(struct dwc2_hsotg *hsotg)
 	p->phy_type = DWC2_PHY_TYPE_PARAM_UTMI;
 	p->ahbcfg = GAHBCFG_HBSTLEN_INCR8 <<
 		GAHBCFG_HBSTLEN_SHIFT;
+	p->power_down = DWC2_POWER_DOWN_PARAM_NONE;
 }
 
 static void dwc2_set_amcc_params(struct dwc2_hsotg *hsotg)
-- 
2.19.2