From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BE47622969B; Thu, 12 Dec 2024 17:01:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734022861; cv=none; b=BYPRDdM8YQ/xxnbhS4JmXQsqD11Ju8iy8V2cvXo7iF2oUpIufrxvtUenM+QS6rrqJZlMdD0l4wizoHYxX7o5m2qqxQ6A5hbou4+UZf2wR/4Y4HXTyDwNMX+O6ZizBUbxBjdSwLa/xVQK2td/dGeUVPXxWHypPOlyJ50LLLxpu4s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734022861; c=relaxed/simple; bh=I2SzrSOhr88tRDOdcrC6N/Lch95PYNhJ6NA/Vn2qPDQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NC96W/oi3vjHFxYvpAO69k9xOSVh3cYoQdcWTEmV7iEnCPmJ+9iKe0ZpdwRMK7mOK/Ay8do6Dzwa51CZnxKMY6yNjVPdyajWNY1dwENghlc5bOCY7dHUD8/WN2RGkES94fjRTAjY7I4QHPBaS9biepUlIuALqD3TDkN1BXxPjWA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=FXPYoh4a; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="FXPYoh4a" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0FC2DC4CECE; Thu, 12 Dec 2024 17:01:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734022861; bh=I2SzrSOhr88tRDOdcrC6N/Lch95PYNhJ6NA/Vn2qPDQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FXPYoh4atCJopa8Ls4qoYAdbW0dnIasVIhKwTqFxbGoCbHYLiMK4j7iPF+xyHhf49 OL/WMFX2C3c7N2+N+l4NO0Hm/lsOxrzd6OkVl2UY45fmLiK0faaOvBNR57f9XNH9D5 OkXDoaKUB0QxYvcExoDdyegshdqAmUL8glGiEvRo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Matthew McClain , Sai Kumar Cholleti , Andy Shevchenko , Bartosz Golaszewski Subject: [PATCH 5.15 325/565] gpio: exar: set value when external pull-up or pull-down is present Date: Thu, 12 Dec 2024 15:58:40 +0100 Message-ID: <20241212144324.447168123@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241212144311.432886635@linuxfoundation.org> References: <20241212144311.432886635@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sai Kumar Cholleti commit 72cef64180de04a7b055b4773c138d78f4ebdb77 upstream. Setting GPIO direction = high, sometimes results in GPIO value = 0. If a GPIO is pulled high, the following construction results in the value being 0 when the desired value is 1: $ echo "high" > /sys/class/gpio/gpio336/direction $ cat /sys/class/gpio/gpio336/value 0 Before the GPIO direction is changed from an input to an output, exar_set_value() is called with value = 1, but since the GPIO is an input when exar_set_value() is called, _regmap_update_bits() reads a 1 due to an external pull-up. regmap_set_bits() sets force_write = false, so the value (1) is not written. When the direction is then changed, the GPIO becomes an output with the value of 0 (the hardware default). regmap_write_bits() sets force_write = true, so the value is always written by exar_set_value() and an external pull-up doesn't affect the outcome of setting direction = high. The same can happen when a GPIO is pulled low, but the scenario is a little more complicated. $ echo high > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1 $ echo in > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 0 $ echo low > /sys/class/gpio/gpio351/direction $ cat /sys/class/gpio/gpio351/value 1 Fixes: 36fb7218e878 ("gpio: exar: switch to using regmap") Co-developed-by: Matthew McClain Signed-off-by: Matthew McClain Signed-off-by: Sai Kumar Cholleti Cc: stable@vger.kernel.org Reviewed-by: Andy Shevchenko Link: https://lore.kernel.org/r/20241105071523.2372032-1-skmr537@gmail.com Signed-off-by: Bartosz Golaszewski Signed-off-by: Greg Kroah-Hartman --- drivers/gpio/gpio-exar.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) --- a/drivers/gpio/gpio-exar.c +++ b/drivers/gpio/gpio-exar.c @@ -80,11 +80,13 @@ static void exar_set_value(struct gpio_c struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip); unsigned int addr = exar_offset_to_lvl_addr(exar_gpio, offset); unsigned int bit = exar_offset_to_bit(exar_gpio, offset); + unsigned int bit_value = value ? BIT(bit) : 0; - if (value) - regmap_set_bits(exar_gpio->regmap, addr, BIT(bit)); - else - regmap_clear_bits(exar_gpio->regmap, addr, BIT(bit)); + /* + * regmap_write_bits() forces value to be written when an external + * pull up/down might otherwise indicate value was already set. + */ + regmap_write_bits(exar_gpio->regmap, addr, BIT(bit), bit_value); } static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,