Hi,
On 22-01-17 23:20, Dmitry Torokhov wrote:
On Sun, Jan 22, 2017 at 09:00:08PM +0100, Hans de Goede wrote:
On some x86 tablets we cannot directly access the GPIOs as they are
claimed by the ACPI tables, so check it the i2c client is not being
power-managed by ACPI before trying to get the power pin GPIO.
Why do we even get this GPIO if driver is not supposed to be using it?
I'd much rather gpio provider hid it from the driver instead of every
driver having this check.
The problem is that the gpio subsys does not really know about ACPI
managed GPIOs the way this works is that the firmware sets a special
"reserved for firmware use" bit in the gpio control register and
directly bit-bangs the gpio control register when it wants to toggle
the gpio. So there is no awareness of these gpios being reserved
(as gpios) at the ACPI level AFAICT.
The hardware specific low-level gpio chip driver checks this bit
when we request the gpio and returns -EBUSY.
Regards,
Hans
Thanks.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
Changes in v2:
-Check acpi_bus_power_manageable() instead of trying to directly
control the acpi power level ourselves
---
drivers/input/touchscreen/silead.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)
diff --git a/drivers/input/touchscreen/silead.c b/drivers/input/touchscreen/silead.c
index 404830a..2fbcd7f 100644
--- a/drivers/input/touchscreen/silead.c
+++ b/drivers/input/touchscreen/silead.c
@@ -31,6 +31,7 @@
#include <linux/irq.h>
#include <linux/regulator/consumer.h>
+#include <acpi/acpi_bus.h>
#include <asm/unaligned.h>
#define SILEAD_TS_NAME "silead_ts"
@@ -494,12 +495,21 @@ static int silead_ts_probe(struct i2c_client *client,
if (error)
return error;
- /* Power GPIO pin */
- data->gpio_power = devm_gpiod_get_optional(dev, "power", GPIOD_OUT_LOW);
- if (IS_ERR(data->gpio_power)) {
- if (PTR_ERR(data->gpio_power) != -EPROBE_DEFER)
- dev_err(dev, "Shutdown GPIO request failed\n");
- return PTR_ERR(data->gpio_power);
+ /*
+ * If device power is not managed by ACPI, get the power_gpio
+ * and manage it ourselves.
+ */
+#ifdef CONFIG_ACPI
+ if (!acpi_bus_power_manageable(ACPI_HANDLE(dev)))
+#endif
+ {
+ data->gpio_power = devm_gpiod_get_optional(dev, "power",
+ GPIOD_OUT_LOW);
+ if (IS_ERR(data->gpio_power)) {
+ if (PTR_ERR(data->gpio_power) != -EPROBE_DEFER)
+ dev_err(dev, "Power GPIO request failed\n");
+ return PTR_ERR(data->gpio_power);
+ }
}
error = silead_ts_setup(client);
--
2.9.3
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