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From:   Quentin Schulz <foss+kernel@0leil.net>
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Cc:     Quentin Schulz <quentin.schulz@theobroma-systems.com>,
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Subject: [PATCH v3 2/9] Input: goodix - make gpiod_get honor GPIOD_ASIS
Date:   Mon,  5 Dec 2022 14:40:31 +0100
Message-Id: <20221103-upstream-goodix-reset-v3-2-0975809eb183@theobroma-systems.com>
In-Reply-To: <20221103-upstream-goodix-reset-v3-0-0975809eb183@theobroma-systems.com>
References: <20221103-upstream-goodix-reset-v3-0-0975809eb183@theobroma-systems.com>
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From: Quentin Schulz <quentin.schulz@theobroma-systems.com>

For some reason the ACPI GPIO lookup code (acpi_find_gpio followed by
acpi_gpio_update_gpiod_flags) will override the gpiod_flags
passed to gpiod_get() if it can determine a set of flags from the ACPI
GpioIo entry.

For output pins like the reset pin, this requires a pull bias to be set,
which often is not the case, so then the GPIOD_ASIS which we pass in is
used.

But if a pull bias is specified in the ACPI GpioIo entry for the reset
pin then that gets translated to GPIOD_OUT_LOW or GPIOD_OUT_HIGH meaning
we cannot guarantee the same behavior on all boards.

So this may cause unintended side-effects, c.f. commit a2fd46cd3dbb
("Input: goodix - try not to touch the reset-pin on x86/ACPI devices")
for some background.

This is something which we can fix though, we can force the ACPI GPIO
code to honor the GPIOD_ASIS we pass in by passing
ACPI_GPIO_QUIRK_NO_IO_RESTRICTION to the ACPI gpio mapping.

Suggested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
---
 drivers/input/touchscreen/goodix.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/input/touchscreen/goodix.c b/drivers/input/touchscreen/goodix.c
index d73d4272a8ea5..1639f2f8a31e3 100644
--- a/drivers/input/touchscreen/goodix.c
+++ b/drivers/input/touchscreen/goodix.c
@@ -803,6 +803,7 @@ static int goodix_reset(struct goodix_ts_data *ts)
 		.name = _name, \
 		.data = _params, \
 		.size = _size, \
+		.quirks = ACPI_GPIO_QUIRK_NO_IO_RESTRICTION, \
 	}
 
 static const struct acpi_gpio_params first_gpio = { 0, 0, false };

-- 
b4 0.10.1