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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jan Kiszka <jan.kiszka@siemens.com>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Michal Simek <michal.simek@xilinx.com>
Subject: [PATCH 4.20 154/171] arm64: dts: zcu100-revC: Give wifi some time after power-on
Date:   Tue, 12 Mar 2019 10:08:54 -0700
Message-Id: <20190312170400.768888216@linuxfoundation.org>
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4.20-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jan Kiszka <jan.kiszka@siemens.com>

commit 35a4f89cd4731ac6ec985cd29ddc1630903006b7 upstream.

Somewhere along recent changes to power control of the wl1831, power-on
became very unreliable on the Ultra96, failing like this:

wl1271_sdio: probe of mmc2:0001:1 failed with error -16
wl1271_sdio: probe of mmc2:0001:2 failed with error -16

After playing with some dt parameters and comparing to other users of
this chip, it turned out we need some power-on delay to make things
stable again. In contrast to those other users which define 200 ms,
Ultra96 is already happy with 10 ms.

Fixes: 5869ba0653b9 ("arm64: zynqmp: Add support for Xilinx zcu100-revC")
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm64/boot/dts/xilinx/zynqmp-zcu100-revC.dts |    1 +
 1 file changed, 1 insertion(+)

--- a/arch/arm64/boot/dts/xilinx/zynqmp-zcu100-revC.dts
+++ b/arch/arm64/boot/dts/xilinx/zynqmp-zcu100-revC.dts
@@ -101,6 +101,7 @@
 	sdio_pwrseq: sdio_pwrseq {
 		compatible = "mmc-pwrseq-simple";
 		reset-gpios = <&gpio 7 GPIO_ACTIVE_LOW>; /* WIFI_EN */
+		post-power-on-delay-ms = <10>;
 	};
 };