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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Roger Quadros <rogerq@ti.com>,
        Felipe Balbi <felipe.balbi@linux.intel.com>,
        Tony Lindgren <tony@atomide.com>
Subject: [PATCH 4.14 061/105] ARM: dts: dra7: Disable USB metastability workaround for USB2
Date:   Mon, 11 Nov 2019 19:28:31 +0100
Message-Id: <20191111181444.963730015@linuxfoundation.org>
In-Reply-To: <20191111181421.390326245@linuxfoundation.org>
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From: Roger Quadros <rogerq@ti.com>

commit b8c9c6fa2002b8fd4a9710f76f80f99c6046d48c upstream.

The metastability workaround causes Erratic errors [1]
on the HighSpeed USB PHY which can cause upto 2 seconds
delay in enumerating to a USB host while in Gadget mode.

Disable the Run/Stop metastability workaround to avoid this
ill effect. We are aware that this opens up the opportunity
for Run/Stop metastability, however this issue has never been
observed in TI releases so we think that Run/Stop metastability
is a lesser evil than the PHY Erratic errors. So disable it.

[1] USB controller trace during gadget enumeration
    irq/90-dwc3-969   [000] d...    52.323145: dwc3_event: event
    (00000901): Erratic Error [U0]
    irq/90-dwc3-969   [000] d...    52.560646: dwc3_event: event
    (00000901): Erratic Error [U0]
    irq/90-dwc3-969   [000] d...    52.798144: dwc3_event: event
    (00000901): Erratic Error [U0]

Signed-off-by: Roger Quadros <rogerq@ti.com>
Acked-by: Felipe Balbi <felipe.balbi@linux/intel.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm/boot/dts/dra7.dtsi |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/arm/boot/dts/dra7.dtsi
+++ b/arch/arm/boot/dts/dra7.dtsi
@@ -1540,6 +1540,7 @@
 				dr_mode = "otg";
 				snps,dis_u3_susphy_quirk;
 				snps,dis_u2_susphy_quirk;
+				snps,dis_metastability_quirk;
 			};
 		};