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From: Linus Walleij <linus.walleij@linaro.org>
To: arm@kernel.org
Cc: Linus Walleij <linus.walleij@linaro.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH] ARM: dts: nomadik: Fix polarity of SPI CS
Date: Mon, 18 Mar 2019 16:31:22 +0100	[thread overview]
Message-ID: <20190318153122.10257-1-linus.walleij@linaro.org> (raw)

The SPI DT bindings are for historical reasons a pitfall,
the ability to flag a GPIO line as active high/low with
the second cell flags was introduced later so the SPI
subsystem will only accept the bool flag spi-cs-high
to indicate that the line is active high.

It worked by mistake, but the mistake was corrected
in another commit.

The comment in the DTS file was also misleading: this
CS is indeed active high.

Fixes: cffbb02dafa3 ("ARM: dts: nomadik: Augment NHK15 panel setting")
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
ARM SoC people: please apply this directly for fixes
if you're OK with it.
---
 arch/arm/boot/dts/ste-nomadik-nhk15.dts | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/arm/boot/dts/ste-nomadik-nhk15.dts b/arch/arm/boot/dts/ste-nomadik-nhk15.dts
index 04066f9cb8a3..f2f6558a00f1 100644
--- a/arch/arm/boot/dts/ste-nomadik-nhk15.dts
+++ b/arch/arm/boot/dts/ste-nomadik-nhk15.dts
@@ -213,12 +213,13 @@
 		gpio-sck = <&gpio0 5 GPIO_ACTIVE_HIGH>;
 		gpio-mosi = <&gpio0 4 GPIO_ACTIVE_HIGH>;
 		/*
-		 * It's not actually active high, but the frameworks assume
-		 * the polarity of the passed-in GPIO is "normal" (active
-		 * high) then actively drives the line low to select the
-		 * chip.
+		 * This chipselect is active high. Just setting the flags
+		 * to GPIO_ACTIVE_HIGH is not enough for the SPI DT bindings,
+		 * it will be ignored, only the special "spi-cs-high" flag
+		 * really counts.
 		 */
 		cs-gpios = <&gpio0 6 GPIO_ACTIVE_HIGH>;
+		spi-cs-high;
 		num-chipselects = <1>;
 
 		/*
-- 
2.20.1


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             reply	other threads:[~2019-03-18 15:31 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-18 15:31 Linus Walleij [this message]
2019-03-25 16:03 ` [PATCH] ARM: dts: nomadik: Fix polarity of SPI CS Arnd Bergmann
2019-04-07 10:16 ` Linus Walleij
2019-04-07 22:19   ` Olof Johansson

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