linux-kernel - [PATCH 1/1] ARM: dts: stm32: use usbphyc ck_usbo

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Date:   Wed, 6 Oct 2021 11:53:55 +0200
From:   Amelie Delaunay <amelie.delaunay@...s.st.com>
To:     Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...s.st.com>,
        Rob Herring <robh+dt@...nel.org>
CC:     <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Amelie Delaunay <amelie.delaunay@...s.st.com>
Subject: [PATCH 1/1] ARM: dts: stm32: use usbphyc ck_usbo_48m as USBH OHCI clock on stm32mp151

Referring to the note under USBH reset and clocks chapter of RM0436,
"In order to access USBH_OHCI registers it is necessary to activate the USB
clocks by enabling the PLL controlled by USBPHYC" (ck_usbo_48m).

The point is, when USBPHYC PLL is not enabled, OHCI register access
freezes the resume from STANDBY. It is the case when dual USBH is enabled,
instead of OTG + single USBH.
When OTG is probed, as ck_usbo_48m is USBO clock parent, then USBPHYC PLL
is enabled and OHCI register access is OK.

This patch adds ck_usbo_48m (provided by USBPHYC PLL) as clock of USBH
OHCI, thus USBPHYC PLL will be enabled and OHCI register access will be OK.

Signed-off-by: Amelie Delaunay <amelie.delaunay@...s.st.com>
---
 arch/arm/boot/dts/stm32mp151.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/stm32mp151.dtsi b/arch/arm/boot/dts/stm32mp151.dtsi
index bd289bf5d269..fe194c787e6c 100644
--- a/arch/arm/boot/dts/stm32mp151.dtsi
+++ b/arch/arm/boot/dts/stm32mp151.dtsi
@@ -1452,7 +1452,7 @@ stmmac_axi_config_0: stmmac-axi-config {
 		usbh_ohci: usb@...0c000 {
 			compatible = "generic-ohci";
 			reg = <0x5800c000 0x1000>;
-			clocks = <&rcc USBH>;
+			clocks = <&rcc USBH>, <&usbphyc>;
 			resets = <&rcc USBH_R>;
 			interrupts = <GIC_SPI 74 IRQ_TYPE_LEVEL_HIGH>;
 			status = "disabled";
-- 
2.25.1