From: Timur Tabi <timur@codeaurora.org> To: linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-gpio@vger.kernel.org, Linus Walleij <linus.walleij@linaro.org>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Mika Westerberg <mika.westerberg@linux.intel.com>, thierry.reding@gmail.com, Stephen Boyd <sboyd@codeaurora.org>, david.brown@linaro.org, andy.gross@linaro.org, Bjorn Andersson <bjorn.andersson@linaro.org>, Varadarajan Narayanan <varada@codeaurora.org>, Archit Taneja <architt@codeaurora.org> Cc: timur@codeaurora.org Subject: [PATCH 1/4] [v2] Revert "gpio: set up initial state from .get_direction()" Date: Fri, 1 Dec 2017 17:28:21 -0600 [thread overview] Message-ID: <1512170904-4749-2-git-send-email-timur@codeaurora.org> (raw) In-Reply-To: <1512170904-4749-1-git-send-email-timur@codeaurora.org> This reverts commit 72d3200061776264941be1b5a9bb8e926b3b30a5. We cannot blindly query the direction of all GPIOs when the pins are first registered. The get_direction callback normally triggers a read/write to hardware, but we shouldn't be touching the hardware for an individual GPIO until after it's been properly claimed. Signed-off-by: Timur Tabi <timur@codeaurora.org> --- drivers/gpio/gpiolib.c | 31 +++++++------------------------ 1 file changed, 7 insertions(+), 24 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 641a5eb552cb..168dd831551d 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1207,31 +1207,14 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data, struct gpio_desc *desc = &gdev->descs[i]; desc->gdev = gdev; - /* - * REVISIT: most hardware initializes GPIOs as inputs - * (often with pullups enabled) so power usage is - * minimized. Linux code should set the gpio direction - * first thing; but until it does, and in case - * chip->get_direction is not set, we may expose the - * wrong direction in sysfs. - */ - - if (chip->get_direction) { - /* - * If we have .get_direction, set up the initial - * direction flag from the hardware. - */ - int dir = chip->get_direction(chip, i); - if (!dir) - set_bit(FLAG_IS_OUT, &desc->flags); - } else if (!chip->direction_input) { - /* - * If the chip lacks the .direction_input callback - * we logically assume all lines are outputs. - */ - set_bit(FLAG_IS_OUT, &desc->flags); - } + /* REVISIT: most hardware initializes GPIOs as inputs (often + * with pullups enabled) so power usage is minimized. Linux + * code should set the gpio direction first thing; but until + * it does, and in case chip->get_direction is not set, we may + * expose the wrong direction in sysfs. + */ + desc->flags = !chip->direction_input ? (1 << FLAG_IS_OUT) : 0; } #ifdef CONFIG_PINCTRL -- Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
WARNING: multiple messages have this Message-ID (diff)
From: timur@codeaurora.org (Timur Tabi) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH 1/4] [v2] Revert "gpio: set up initial state from .get_direction()" Date: Fri, 1 Dec 2017 17:28:21 -0600 [thread overview] Message-ID: <1512170904-4749-2-git-send-email-timur@codeaurora.org> (raw) In-Reply-To: <1512170904-4749-1-git-send-email-timur@codeaurora.org> This reverts commit 72d3200061776264941be1b5a9bb8e926b3b30a5. We cannot blindly query the direction of all GPIOs when the pins are first registered. The get_direction callback normally triggers a read/write to hardware, but we shouldn't be touching the hardware for an individual GPIO until after it's been properly claimed. Signed-off-by: Timur Tabi <timur@codeaurora.org> --- drivers/gpio/gpiolib.c | 31 +++++++------------------------ 1 file changed, 7 insertions(+), 24 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 641a5eb552cb..168dd831551d 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1207,31 +1207,14 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data, struct gpio_desc *desc = &gdev->descs[i]; desc->gdev = gdev; - /* - * REVISIT: most hardware initializes GPIOs as inputs - * (often with pullups enabled) so power usage is - * minimized. Linux code should set the gpio direction - * first thing; but until it does, and in case - * chip->get_direction is not set, we may expose the - * wrong direction in sysfs. - */ - - if (chip->get_direction) { - /* - * If we have .get_direction, set up the initial - * direction flag from the hardware. - */ - int dir = chip->get_direction(chip, i); - if (!dir) - set_bit(FLAG_IS_OUT, &desc->flags); - } else if (!chip->direction_input) { - /* - * If the chip lacks the .direction_input callback - * we logically assume all lines are outputs. - */ - set_bit(FLAG_IS_OUT, &desc->flags); - } + /* REVISIT: most hardware initializes GPIOs as inputs (often + * with pullups enabled) so power usage is minimized. Linux + * code should set the gpio direction first thing; but until + * it does, and in case chip->get_direction is not set, we may + * expose the wrong direction in sysfs. + */ + desc->flags = !chip->direction_input ? (1 << FLAG_IS_OUT) : 0; } #ifdef CONFIG_PINCTRL -- Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.
next prev parent reply other threads:[~2017-12-01 23:28 UTC|newest] Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-12-01 23:28 [PATCH 0/4] [v8] pinctrl: qcom: add support for sparse GPIOs Timur Tabi 2017-12-01 23:28 ` Timur Tabi 2017-12-01 23:28 ` Timur Tabi [this message] 2017-12-01 23:28 ` [PATCH 1/4] [v2] Revert "gpio: set up initial state from .get_direction()" Timur Tabi 2017-12-01 23:28 ` [PATCH 2/4] [v2] gpiolib: add bitmask for valid GPIO lines Timur Tabi 2017-12-01 23:28 ` Timur Tabi 2017-12-12 9:58 ` Andy Shevchenko 2017-12-12 9:58 ` Andy Shevchenko 2017-12-12 20:16 ` Timur Tabi 2017-12-12 20:16 ` Timur Tabi 2017-12-01 23:28 ` [PATCH 3/4] [v7] pinctrl: qcom: disable GPIO groups with no pins Timur Tabi 2017-12-01 23:28 ` Timur Tabi 2017-12-01 23:28 ` [PATCH 4/4] [v4] pinctrl: qcom: qdf2xxx: add support for new ACPI HID QCOM8002 Timur Tabi 2017-12-01 23:28 ` Timur Tabi 2017-12-12 10:05 ` Andy Shevchenko 2017-12-12 10:05 ` Andy Shevchenko 2017-12-12 20:17 ` Timur Tabi 2017-12-12 20:17 ` Timur Tabi 2017-12-13 14:32 ` Andy Shevchenko 2017-12-13 14:32 ` Andy Shevchenko 2017-12-13 14:46 ` Timur Tabi 2017-12-13 14:46 ` Timur Tabi 2017-12-13 15:18 ` Timur Tabi 2017-12-13 15:18 ` Timur Tabi 2017-12-13 15:40 ` Andy Shevchenko 2017-12-13 15:40 ` Andy Shevchenko [not found] ` <1512170904-4749-5-git-send-email-timur-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org> 2017-12-12 10:42 ` Linus Walleij 2017-12-12 10:42 ` Linus Walleij 2017-12-12 11:07 ` Andy Shevchenko 2017-12-12 11:07 ` Andy Shevchenko 2017-12-12 20:27 ` Timur Tabi 2017-12-12 20:27 ` Timur Tabi 2017-12-13 14:36 ` Andy Shevchenko 2017-12-13 14:36 ` Andy Shevchenko 2017-12-13 14:47 ` Timur Tabi 2017-12-13 14:47 ` Timur Tabi -- strict thread matches above, loose matches on Subject: below -- 2017-11-07 23:07 [PATCH 0/4] [v7] pinctrl: qcom: add support for sparse GPIOs Timur Tabi 2017-11-07 23:07 ` [PATCH 1/4] [v2] Revert "gpio: set up initial state from .get_direction()" Timur Tabi 2017-11-07 23:07 ` Timur Tabi
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