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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.

  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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