linux-kernel - [PATCH] arm64: dts: hikey: Give wifi some time after power-on

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Date:   Sun, 30 Dec 2018 12:38:11 +0100
From:   Jan Kiszka <jan.kiszka@....de>
To:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Wei Xu <xuwei5@...ilicon.com>
Cc:     Ryan Grachek <ryan@...ted.us>,
        John Stultz <john.stultz@...aro.org>,
        linux-wireless@...r.kernel.org, "Reizer, Eyal" <eyalr@...com>,
        Valentin Schneider <valentin.schneider@....com>
Subject: [PATCH] arm64: dts: hikey: Give wifi some time after power-on

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

Somewhere along recent changes to power control of the wl1835, power-on
became very unreliable on the hikey, 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, the
hikey is already very happy with 1 ms.

Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
---

Tested with 4.19 and linus/master.

  arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts | 1 +
  1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts 
b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
index f4964bee6a1a..1e771bf201b9 100644
--- a/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
+++ b/arch/arm64/boot/dts/hisilicon/hi6220-hikey.dts
@@ -118,6 +118,7 @@
  		reset-gpios = <&gpio0 5 GPIO_ACTIVE_LOW>;
  		clocks = <&pmic>;
  		clock-names = "ext_clock";
+		post-power-on-delay-ms = <1>;
  		power-off-delay-us = <10>;
  	};

-- 
2.16.4