Date: Tue, 21 Jul 2020 07:35:04 +0000 (UTC) From: Andriy Gapon <avg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r363382 - head/sys/dev/gpio Message-ID: <202007210735.06L7Z4HM057413@repo.freebsd.org>
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Author: avg Date: Tue Jul 21 07:35:03 2020 New Revision: 363382 URL: https://svnweb.freebsd.org/changeset/base/363382 Log: gpioiic: never drive lines active high I2C communication is done by a combination of driving a line low or letting it float, so that it is either pulled up or driven low by another party. r355276 besides the stated goal of the change -- using the new GPIO API -- also changed the logic, so that active state is signaled by actively driving a line. That worked with iicbb prior to r362042, but stopped working after that commit on at least some hardware. My guess that the breakage was related to getting an ACK bit. A device expected to be able to drive SDA actively low, but controller was actively driving it high for some time. Anyway, this change seems to fix the problem. Tested using gpioiic on Orange Pi PC Plus with HTU21 sensor. Reported by: Nick Kostirya <nikolay.kostirya@i11.co> Reviewed by: manu MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D25684 Modified: head/sys/dev/gpio/gpioiic.c Modified: head/sys/dev/gpio/gpioiic.c ============================================================================== --- head/sys/dev/gpio/gpioiic.c Mon Jul 20 23:57:53 2020 (r363381) +++ head/sys/dev/gpio/gpioiic.c Tue Jul 21 07:35:03 2020 (r363382) @@ -191,16 +191,14 @@ static void gpioiic_setsda(device_t dev, int val) { struct gpioiic_softc *sc = device_get_softc(dev); - int err; - /* - * Some controllers cannot set an output value while a pin is in input - * mode; in that case we set the pin again after changing mode. - */ - err = gpio_pin_set_active(sc->sdapin, val); - gpio_pin_setflags(sc->sdapin, GPIO_PIN_OUTPUT | GPIO_PIN_OPENDRAIN); - if (err != 0) - gpio_pin_set_active(sc->sdapin, val); + if (val) { + gpio_pin_setflags(sc->sdapin, GPIO_PIN_INPUT); + } else { + gpio_pin_setflags(sc->sdapin, + GPIO_PIN_OUTPUT | GPIO_PIN_OPENDRAIN); + gpio_pin_set_active(sc->sdapin, 0); + } } static void @@ -208,8 +206,13 @@ gpioiic_setscl(device_t dev, int val) { struct gpioiic_softc *sc = device_get_softc(dev); - gpio_pin_setflags(sc->sclpin, GPIO_PIN_OUTPUT | GPIO_PIN_OPENDRAIN); - gpio_pin_set_active(sc->sclpin, val); + if (val) { + gpio_pin_setflags(sc->sclpin, GPIO_PIN_INPUT); + } else { + gpio_pin_setflags(sc->sclpin, + GPIO_PIN_OUTPUT | GPIO_PIN_OPENDRAIN); + gpio_pin_set_active(sc->sclpin, 0); + } } static int
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