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>
Cc: timur@codeaurora.org
Subject: [PATCH 1/4] [v2] Revert "gpio: set up initial state from .get_direction()"
Date: Tue, 7 Nov 2017 17:07:33 -0600 [thread overview]
Message-ID: <1510096056-13765-2-git-send-email-timur@codeaurora.org> (raw)
In-Reply-To: <1510096056-13765-1-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 eb80dac4e26a..60553af4c004 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -1221,31 +1221,14 @@ int gpiochip_add_data(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:[~2017-11-07 23:07 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-07 23:07 [PATCH 0/4] [v7] pinctrl: qcom: add support for sparse GPIOs Timur Tabi
2017-11-07 23:07 ` Timur Tabi [this message]
2017-11-07 23:07 ` [PATCH 2/4] gpiolib: add bitmask for valid GPIO lines Timur Tabi
[not found] ` <b2b5374b-17a6-e068-ef8b-edc90d34c352@codeaurora.org>
2017-11-15 6:28 ` Fwd: " Varadarajan Narayanan
2017-11-15 11:38 ` Andy Shevchenko
2017-11-15 15:15 ` Timur Tabi
2017-12-01 11:38 ` Archit Taneja
2017-12-01 17:16 ` Timur Tabi
2017-11-07 23:07 ` [PATCH 3/4] [v6] pinctrl: qcom: disable GPIO groups with no pins Timur Tabi
2017-11-17 2:43 ` Stephen Boyd
2017-11-17 2:58 ` Timur Tabi
2017-11-17 17:46 ` Stephen Boyd
2017-11-17 17:49 ` Timur Tabi
2017-11-17 21:42 ` Stephen Boyd
2017-11-17 21:44 ` Timur Tabi
2017-11-07 23:07 ` [PATCH 4/4] [v3] pinctrl: qcom: qdf2xxx: add support for new ACPI HID QCOM8002 Timur Tabi
[not found] ` <133cd447-c5c8-2b3e-1ae2-484307d5e39d@codeaurora.org>
2017-11-15 6:47 ` Fwd: " Varadarajan Narayanan
2017-11-15 15:14 ` Timur Tabi
2017-11-13 19:19 ` [PATCH 0/4] [v7] pinctrl: qcom: add support for sparse GPIOs Timur Tabi
2017-11-13 21:49 ` Linus Walleij
2017-11-13 21:53 ` Timur Tabi
2017-11-14 10:03 ` Linus Walleij
2017-11-15 15:06 ` Timur Tabi
-- strict thread matches above, loose matches on Subject: below --
2017-12-01 23:28 [PATCH 0/4] [v8] " Timur Tabi
2017-12-01 23:28 ` [PATCH 1/4] [v2] Revert "gpio: set up initial state from .get_direction()" Timur Tabi
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