linux-kernel - [PATCH v3 1/8] arm64: dts: ti: k3-am62x-sk-common: Update main-i2c1 frequency

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Message-ID: <20230728173438.12995-2-a-bhatia1@ti.com>
Date:   Fri, 28 Jul 2023 23:04:31 +0530
From:   Aradhya Bhatia <a-bhatia1@...com>
To:     Nishanth Menon <nm@...com>, Vignesh Raghavendra <vigneshr@...com>,
        Tero Kristo <kristo@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Conor Dooley <conor+dt@...nel.org>
CC:     Devicetree List <devicetree@...r.kernel.org>,
        Linux Kernel List <linux-kernel@...r.kernel.org>,
        Linux ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
        Tomi Valkeinen <tomi.valkeinen@...asonboard.com>,
        Rahul T R <r-ravikumar@...com>,
        Devarsh Thakkar <devarsht@...com>,
        Jai Luthra <j-luthra@...com>,
        Jayesh Choudhary <j-choudhary@...com>,
        Aradhya Bhatia <a-bhatia1@...com>
Subject: [PATCH v3 1/8] arm64: dts: ti: k3-am62x-sk-common: Update main-i2c1 frequency

The Display Data Channel (DDC) transactions between an HDMI transmitter
(SIL9022A in this case) and an HDMI monitor, occur at a maximum of
100KHz. That's the maximum supported frequency within DDC standards.

While the SIL9022A can transact with the core at 400KHz, it needs to
drop the frequency to 100KHz when communicating with the monitor,
otherwise, the i2c controller times out and shows warning like this.

[  985.773431] omap_i2c 20010000.i2c: controller timed out

That feature, however, has not been enabled in the SIL9022 driver.

Since, dropping the frequency doesn't affect any other devices on the
bus, drop the main-i2c1 frequency from 400KHz to 100KHz.

Signed-off-by: Aradhya Bhatia <a-bhatia1@...com>
---
 arch/arm64/boot/dts/ti/k3-am62x-sk-common.dtsi | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/ti/k3-am62x-sk-common.dtsi b/arch/arm64/boot/dts/ti/k3-am62x-sk-common.dtsi
index 34c8ffc553ec..540ed8a0d7fb 100644
--- a/arch/arm64/boot/dts/ti/k3-am62x-sk-common.dtsi
+++ b/arch/arm64/boot/dts/ti/k3-am62x-sk-common.dtsi
@@ -300,7 +300,7 @@ &main_i2c1 {
 	status = "okay";
 	pinctrl-names = "default";
 	pinctrl-0 = <&main_i2c1_pins_default>;
-	clock-frequency = <400000>;
+	clock-frequency = <100000>;
 
 	tlv320aic3106: audio-codec@1b {
 		#sound-dai-cells = <0>;
-- 
2.40.1