linux-kernel - [PATCH v3 1/2] pinctrl: mlxbf3: Remove gpio_disable

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Date:   Thu, 17 Aug 2023 21:21:10 -0400
From:   Asmaa Mnebhi <asmaa@...dia.com>
To:     <andy.shevchenko@...il.com>, <linux-gpio@...r.kernel.org>,
        <linus.walleij@...aro.org>, <bgolaszewski@...libre.com>,
        <brgl@...ev.pl>, <linux-kernel@...r.kernel.org>
CC:     Asmaa Mnebhi <asmaa@...dia.com>
Subject: [PATCH v3 1/2] pinctrl: mlxbf3: Remove gpio_disable_free()

Remove support for gpio_disable_free() because it is called when the libgpiod
command "gpioset" is invoked. This gives the GPIO control back to hardware which
cancels out the effort to set the GPIO value.

Reminder of the code flow to change a GPIO value from software:
1) All GPIOs are controlled by hardware by default
2) To change the GPIO value, enable software control via a mux.
3) Once software has control over the GPIO pin, the gpio-mlxbf3 driver
   will be able to change the direction and value of the GPIO.

When the user runs "gpioset gpiochip0 0=0" for example, the gpio
pin value should change from 1 to 0. In this case, mlxbf3_gpio_request_enable()
is called via gpiochip_generic_request(). The latter switches GPIO control from
hardware to software. Then the GPIO value is changed from 1 to 0. However,
gpio_disable_free() is also called which changes control back to hardware
which changes the GPIO value back to 1.

Fixes: d11f932808d ("pinctrl: mlxbf3: Add pinctrl driver support")
Signed-off-by: Asmaa Mnebhi <asmaa@...dia.com>
---
v2->v3:
- No changes
v1->v2:
- No changes 

 drivers/pinctrl/pinctrl-mlxbf3.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/drivers/pinctrl/pinctrl-mlxbf3.c b/drivers/pinctrl/pinctrl-mlxbf3.c
index d9944e6a0af9..0e852a0d5ec2 100644
--- a/drivers/pinctrl/pinctrl-mlxbf3.c
+++ b/drivers/pinctrl/pinctrl-mlxbf3.c
@@ -223,26 +223,12 @@ static int mlxbf3_gpio_request_enable(struct pinctrl_dev *pctldev,
 	return 0;
 }

-static void mlxbf3_gpio_disable_free(struct pinctrl_dev *pctldev,
-				    struct pinctrl_gpio_range *range,
-				    unsigned int offset)
-{
-	struct mlxbf3_pinctrl *priv = pinctrl_dev_get_drvdata(pctldev);
-
-	/* disable GPIO functionality by giving control back to hardware */
-	if (offset < MLXBF3_NGPIOS_GPIO0)
-		writel(BIT(offset), priv->fw_ctrl_clr0);
-	else
-		writel(BIT(offset % MLXBF3_NGPIOS_GPIO0), priv->fw_ctrl_clr1);
-}
-
 static const struct pinmux_ops mlxbf3_pmx_ops = {
 	.get_functions_count = mlxbf3_pmx_get_funcs_count,
 	.get_function_name = mlxbf3_pmx_get_func_name,
 	.get_function_groups = mlxbf3_pmx_get_groups,
 	.set_mux = mlxbf3_pmx_set,
 	.gpio_request_enable = mlxbf3_gpio_request_enable,
-	.gpio_disable_free = mlxbf3_gpio_disable_free,
 };

 static struct pinctrl_desc mlxbf3_pin_desc = {
-- 
2.30.1