linux-kernel - [Patch v2] arm64: dts: qcom: sc7280: Add required-opps for USB

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Date:   Fri, 16 Sep 2022 16:01:24 +0530
From:   Rajendra Nayak <quic_rjendra@...cinc.com>
To:     <agross@...nel.org>, <andersson@...nel.org>,
        <konrad.dybcio@...ainline.org>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>
CC:     <linux-arm-msm@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <sboyd@...nel.org>,
        <mka@...omium.org>, <johan+linaro@...nel.org>,
        <quic_kriskura@...cinc.com>, <dianders@...omium.org>,
        Rajendra Nayak <quic_rjendra@...cinc.com>
Subject: [Patch v2] arm64: dts: qcom: sc7280: Add required-opps for USB

USB has a requirement to put a performance state vote on 'cx'
while active. Use 'required-opps' to pass this information from
device tree, and since all the GDSCs in GCC (including USB) are
sub-domains of cx, we also add cx as a power-domain for GCC.
Now when any of the consumers of the GDSCs (in this case USB)
votes on a perforamance state, genpd framework can identify that
the GDSC itself does not support a performance state and it
then propogates the vote to the parent, which in this case is cx.

This change would also mean that any GDSC in GCC thats left enabled
during low power state (perhaps because its marked with a
ALWAYS_ON flag) can prevent the system from entering low power
since that would prevent cx from transitioning to low power.
Ideally any consumers that would need to have their devices
(partially) powered to support wakeups should look at making the
resp. GDSCs transtion to a Retention (PWRSTS_RET) state instead
of leaving them ALWAYS_ON.

Signed-off-by: Rajendra Nayak <quic_rjendra@...cinc.com>
---
v2:
* Updated the required-opps to nom instead of svs
* Also added required-opps for sec usb device

* This patch is a follow up based on the discussion on the previously
  posted version to support USB performance state voting [1]

* Another patch that this approach depends on is the one to fix the
  handling of PWRSTS_RET in the GDSC driver [2] so we can have USB
  GDSC transtion to a RET state instead of marking it ALWAYS_ON

[1] https://lore.kernel.org/linux-usb/YTduDqCO9aUyAsw1@ripper/
[2] https://lore.kernel.org/all/20220901101756.28164-1-quic_rjendra@quicinc.com/#t

 arch/arm64/boot/dts/qcom/sc7280.dtsi | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/sc7280.dtsi b/arch/arm64/boot/dts/qcom/sc7280.dtsi
index 13d7f267b289..623cb1f78b55 100644
--- a/arch/arm64/boot/dts/qcom/sc7280.dtsi
+++ b/arch/arm64/boot/dts/qcom/sc7280.dtsi
@@ -828,6 +828,7 @@
 			#clock-cells = <1>;
 			#reset-cells = <1>;
 			#power-domain-cells = <1>;
+			power-domains = <&rpmhpd SC7280_CX>;
 		};

 		ipcc: mailbox@...000 {
@@ -3181,6 +3182,7 @@
 					  "dm_hs_phy_irq";

 			power-domains = <&gcc GCC_USB30_SEC_GDSC>;
+			required-opps = <&rpmhpd_opp_nom>;

 			resets = <&gcc GCC_USB30_SEC_BCR>;

@@ -3367,6 +3369,7 @@
 					  "ss_phy_irq";

 			power-domains = <&gcc GCC_USB30_PRIM_GDSC>;
+			required-opps = <&rpmhpd_opp_nom>;

 			resets = <&gcc GCC_USB30_PRIM_BCR>;

-- 
2.17.1