On Thursday 06 April 2017 09:40 PM, Andy Shevchenko wrote:
On Thu, Apr 6, 2017 at 4:35 PM, Laxman Dewangan <ldewangan@xxxxxxxxxx> wrote:
Currently, the GPIO interface is said to Open Drain if it is Single
Ended and active LOW. Similarly, it is said as Open Source if it is
Single Ended and active HIGH.
The active HIGH/LOW is used in the interface for setting the pin
state to HIGH or LOW when enabling/disabling the interface.
In Open Drain interface, pin is set to HIGH by putting pin in
high impedance and LOW by driving to the LOW.
In Open Source interface, pin is set to HIGH by driving pin to
HIGH and set to LOW by putting pin in high impedance.
With above, the Open Drain/Source is unrelated to the active LOW/HIGH
in interface. There is interface where the enable/disable of interface
is ether active LOW or HIGH but it is Open Drain type.
Hence decouple the Open Drain with Single Ended + Active LOW and
Open Source with Single Ended + Active HIGH.
Adding different flag for the Open Drain/Open Source which is valid
only when Single ended flag is enabled.
if (single_ended) {
- if (active_low)
+ if (open_drain)
This breaks ACPI case, right?
In acpi case, single_ended is not handled. It only handles the active LOW.
From code:
bool active_low = false;
bool single_ended = false;
int ret;
if (!fwnode)
return ERR_PTR(-EINVAL);
if (is_of_node(fwnode)) {
enum of_gpio_flags flags;
desc = of_get_named_gpiod_flags(to_of_node(fwnode),
propname,
index, &flags);
if (!IS_ERR(desc)) {
active_low = flags & OF_GPIO_ACTIVE_LOW;
single_ended = flags & OF_GPIO_SINGLE_ENDED;
}
} else if (is_acpi_node(fwnode)) {
struct acpi_gpio_info info;
desc = acpi_node_get_gpiod(fwnode, propname, index, &info);
if (!IS_ERR(desc))
active_low = info.polarity == GPIO_ACTIVE_LOW;
}
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