linux-kernel - [PATCH v3 06/19] arm64: dts: qcom: Disable USB U1/U2 entry for SM6350

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Message-ID: <20241218102707.76272-7-quic_prashk@quicinc.com>
Date: Wed, 18 Dec 2024 15:56:54 +0530
From: Prashanth K <quic_prashk@...cinc.com>
To: Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio
	<konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski
	<krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Krishna Kurapati
	<krishna.kurapati@....qualcomm.com>
CC: <linux-kernel@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <cros-qcom-dts-watchers@...omium.org>,
        Prashanth K <quic_prashk@...cinc.com>
Subject: [PATCH v3 06/19] arm64: dts: qcom: Disable USB U1/U2 entry for SM6350

From: Krishna Kurapati <krishna.kurapati@....qualcomm.com>

Disable U1 and U2 power-saving states to improve stability of USB.
These low-power link states, designed to reduce power consumption
during idle periods, can cause issues in latency-sensitive or high
throughput use cases. Over the years, some of the issues seen are
as follows:

1. In device mode of operation, when UVC is active, enabling U1/U2
is sometimes causing packets drops due to delay in entry/exit of
intermittent these low power states. These packet drops are often
reflected as missed isochronous transfers, as the controller wasn't
able to send packet in that microframe interval and hence glitches
are seen on the final transmitted video output.

2. On older targets like SM8150/SM8250/SM8350, there have been
throughput issues seen during tethering use cases.

Disabling these intermittent power states enhances device stability
without affecting power usage.

Signed-off-by: Krishna Kurapati <krishna.kurapati@....qualcomm.com>
Signed-off-by: Prashanth K <quic_prashk@...cinc.com>
---
 arch/arm64/boot/dts/qcom/sm6350.dtsi | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sm6350.dtsi b/arch/arm64/boot/dts/qcom/sm6350.dtsi
index 8d697280249f..e64447b765a2 100644
--- a/arch/arm64/boot/dts/qcom/sm6350.dtsi
+++ b/arch/arm64/boot/dts/qcom/sm6350.dtsi
@@ -1924,6 +1924,8 @@ usb_1_dwc3: usb@...0000 {
 				snps,has-lpm-erratum;
 				snps,hird-threshold = /bits/ 8 <0x10>;
 				snps,parkmode-disable-ss-quirk;
+				snps,dis-u1-entry-quirk;
+				snps,dis-u2-entry-quirk;
 				phys = <&usb_1_hsphy>, <&usb_1_qmpphy QMP_USB43DP_USB3_PHY>;
 				phy-names = "usb2-phy", "usb3-phy";
 				usb-role-switch;
-- 
2.25.1