linux-kernel - [RFC 1/2] ARM: dts: Fix-up EMMC2 controller's frequency

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Date:   Thu, 25 Feb 2021 10:52:15 +0100
From:   Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
To:     linux-arm-kernel@...ts.infradead.org, linux-mmc@...r.kernel.org,
        devicetree@...r.kernel.org, bcm-kernel-feedback-list@...adcom.com,
        linux-rpi-kernel@...ts.infradead.org,
        Rob Herring <robh+dt@...nel.org>,
        Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
Cc:     f.fainelli@...il.com, phil@...pberrypi.com,
        tim.gover@...pberrypi.com, adrian.hunter@...el.com,
        sbranden@...adcom.com, alcooperx@...il.com,
        linux-kernel@...r.kernel.org
Subject: [RFC 1/2] ARM: dts: Fix-up EMMC2 controller's frequency

Force emmc2's frequency to 150MHz as the default 100MHz (set by FW)
seems to interfere with the VPU clock when setup at frequencies bigger
than 500MHz, causing unwarranted SDHCI CMD hangs when no SD card is
present.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@...e.de>
---
 arch/arm/boot/dts/bcm2711-rpi-4-b.dts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
index 3b4ab947492a..9aa8408d9960 100644
--- a/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
+++ b/arch/arm/boot/dts/bcm2711-rpi-4-b.dts
@@ -257,6 +257,12 @@ &emmc2 {
 	vqmmc-supply = <&sd_io_1v8_reg>;
 	vmmc-supply = <&sd_vcc_reg>;
 	broken-cd;
+	/*
+	 * Force the frequency to 150MHz as the default 100MHz seems to
+	 * interfere with the VPU clock when setup at frequencies bigger than
+	 * 500MHz, causing unwarranted CMD hangs.
+	 */
+	clock-frequency = <150000000>;
 	status = "okay";
 };
 
-- 
2.30.1