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Documentation: firmware-guide: gpio-properties: Spelling and style fixes

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- Use consistent style for active-high and active-low
 - For C and ASL code snippets use 4-space indentation consistently
 - Interleave case examples with the explanations of the certain case
 - Remove or add commas when appropriate

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Link: https://patch.msgid.link/20250626130109.215848-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit is contained in:
Andy Shevchenko 2025-06-26 16:01:09 +03:00 • committed by Rafael J. Wysocki
parent d0b3b7b22d
commit 904cf14f91
1 changed files with 15 additions and 15 deletions
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30
Documentation/firmware-guide/acpi/gpio-properties.rst
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@ -6,7 +6,7 @@ _DSD Device Properties Related to GPIO
With the release of ACPI 5.1, the _DSD configuration object finally
allows names to be given to GPIOs (and other things as well) returned
by _CRS. Previously, we were only able to use an integer index to find
by _CRS. Previously we were only able to use an integer index to find
the corresponding GPIO, which is pretty error prone (it depends on
the _CRS output ordering, for example).
@ -49,11 +49,11 @@ index
pin
Pin in the GpioIo()/GpioInt() resource. Typically this is zero.
active_low
If 1, the GPIO is marked as active_low.
If 1, the GPIO is marked as active-low.
Since ACPI GpioIo() resource does not have a field saying whether it is
active low or high, the "active_low" argument can be used here. Setting
it to 1 marks the GPIO as active low.
active-low or active-high, the "active_low" argument can be used here.
Setting it to 1 marks the GPIO as active-low.
Note, active_low in _DSD does not make sense for GpioInt() resource and
must be 0. GpioInt() resource has its own means of defining it.
@ -231,8 +231,8 @@ In those cases ACPI device identification objects, _HID, _CID, _CLS, _SUB, _HRV,
available to the driver can be used to identify the device and that is supposed
to be sufficient to determine the meaning and purpose of all of the GPIO lines
listed by the GpioIo()/GpioInt() resources returned by _CRS. In other words,
the driver is supposed to know what to use the GpioIo()/GpioInt() resources for
once it has identified the device. Having done that, it can simply assign names
the driver is supposed to know what to use from the GpioIo()/GpioInt() resources
for once it has identified the device. Having done that, it can simply assign names
to the GPIO lines it is going to use and provide the GPIO subsystem with a
mapping between those names and the ACPI GPIO resources corresponding to them.
@ -252,9 +252,9 @@ question would look like this::
static const struct acpi_gpio_params shutdown_gpio = { 0, 0, false };
static const struct acpi_gpio_mapping bluetooth_acpi_gpios[] = {
{ "reset-gpios", &reset_gpio, 1 },
{ "shutdown-gpios", &shutdown_gpio, 1 },
{ }
{ "reset-gpios", &reset_gpio, 1 },
{ "shutdown-gpios", &shutdown_gpio, 1 },
{ }
};
Next, the mapping table needs to be passed as the second argument to
@ -270,7 +270,7 @@ Using the _CRS fallback
If a device does not have _DSD or the driver does not create ACPI GPIO
mapping, the Linux GPIO framework refuses to return any GPIOs. This is
because the driver does not know what it actually gets. For example if we
because the driver does not know what it actually gets. For example, if we
have a device like below::
Device (BTH)
@ -292,7 +292,7 @@ The driver might expect to get the right GPIO when it does::
...error handling...
but since there is no way to know the mapping between "reset" and
the GpioIo() in _CRS desc will hold ERR_PTR(-ENOENT).
the GpioIo() in _CRS the desc will hold ERR_PTR(-ENOENT).
The driver author can solve this by passing the mapping explicitly
(this is the recommended way and it's documented in the above chapter).
@ -318,15 +318,15 @@ Case 1::
desc = gpiod_get(dev, "non-null-connection-id", flags);
desc = gpiod_get_index(dev, "non-null-connection-id", index, flags);
Case 1 assumes that corresponding ACPI device description must have
defined device properties and will prevent from getting any GPIO resources
otherwise.
Case 2::
desc = gpiod_get(dev, NULL, flags);
desc = gpiod_get_index(dev, NULL, index, flags);
Case 1 assumes that corresponding ACPI device description must have
defined device properties and will prevent to getting any GPIO resources
otherwise.
Case 2 explicitly tells GPIO core to look for resources in _CRS.
Be aware that gpiod_get_index() in cases 1 and 2, assuming that there