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94 lines
3.1 KiB
Diff
94 lines
3.1 KiB
Diff
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From 11f89a12530471a2b25c71416e106eaa014818c0 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.com>
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Date: Fri, 5 Jun 2020 16:07:07 +0100
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Subject: [PATCH] overlays: i2c-gpio: Avoid open-drain warnings
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The i2c-gpio driver expects to use a GPIO in open-drain mode. Failure
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to configure it in that way causes alarming warnings in the kernel log.
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The BCM283x and BCM2711 GPIO blocks don't support open-drain mode, but
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gpiolib can emulate it in software if configured correctly.
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Silence the warning by declaring the GPIOs as requiring open-drain
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mode, trusting gpiolib to manage the emulation. The previous
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incarnation of this patch took the other approach of telling the
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i2c-gpio driver that the GPIOs were configured for open-drain, but
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this had the effect of disabling the emulation. In some cases this
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appears to work, but examining the waveforms as analogue voltages
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shows contention, the success or failure depending on drive strengths.
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See: https://github.com/raspberrypi/firmware/issues/1381
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See: https://github.com/raspberrypi/firmware/issues/1401
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Signed-off-by: Phil Elwell <phil@raspberrypi.com>
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---
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arch/arm/boot/dts/overlays/balena-fin-overlay.dts | 5 ++++-
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arch/arm/boot/dts/overlays/i2c-gpio-overlay.dts | 6 ++++--
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arch/arm/boot/dts/overlays/i2c-rtc-gpio-overlay.dts | 6 ++++--
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3 files changed, 12 insertions(+), 5 deletions(-)
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--- a/arch/arm/boot/dts/overlays/balena-fin-overlay.dts
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+++ b/arch/arm/boot/dts/overlays/balena-fin-overlay.dts
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@@ -1,6 +1,8 @@
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/dts-v1/;
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/plugin/;
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+#include <dt-bindings/gpio/gpio.h>
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+
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/{
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compatible = "brcm,bcm2835";
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@@ -48,7 +50,8 @@
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i2c_soft: i2c@0 {
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compatible = "i2c-gpio";
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- gpios = <&gpio 43 0 /* sda */ &gpio 42 0 /* scl */>;
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+ gpios = <&gpio 43 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN) /* sda */
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+ &gpio 42 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN) /* scl */>;
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i2c-gpio,delay-us = <5>;
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i2c-gpio,scl-open-drain;
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i2c-gpio,sda-open-drain;
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--- a/arch/arm/boot/dts/overlays/i2c-gpio-overlay.dts
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+++ b/arch/arm/boot/dts/overlays/i2c-gpio-overlay.dts
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@@ -2,6 +2,8 @@
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/dts-v1/;
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/plugin/;
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+#include <dt-bindings/gpio/gpio.h>
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+
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/ {
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compatible = "brcm,bcm2835";
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@@ -12,8 +14,8 @@
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i2c_gpio: i2c@0 {
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reg = <0xffffffff>;
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compatible = "i2c-gpio";
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- gpios = <&gpio 23 0 /* sda */
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- &gpio 24 0 /* scl */
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+ gpios = <&gpio 23 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN) /* sda */
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+ &gpio 24 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN) /* scl */
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>;
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i2c-gpio,delay-us = <2>; /* ~100 kHz */
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#address-cells = <1>;
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--- a/arch/arm/boot/dts/overlays/i2c-rtc-gpio-overlay.dts
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+++ b/arch/arm/boot/dts/overlays/i2c-rtc-gpio-overlay.dts
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@@ -3,6 +3,8 @@
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/dts-v1/;
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/plugin/;
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+#include <dt-bindings/gpio/gpio.h>
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+
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/ {
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compatible = "brcm,bcm2835";
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@@ -11,8 +13,8 @@
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__overlay__ {
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i2c_gpio: i2c-gpio-rtc@0 {
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compatible = "i2c-gpio";
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- gpios = <&gpio 23 0 /* sda */
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- &gpio 24 0 /* scl */
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+ gpios = <&gpio 23 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN) /* sda */
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+ &gpio 24 (GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN) /* scl */
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>;
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i2c-gpio,delay-us = <2>; /* ~100 kHz */
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#address-cells = <1>;
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