gpio: sx150x: correct and refine reset-on-probe behavior
Replace the arbitrary software-reset call from the device-probe
method, because:
- It is defective. To work correctly, it should be two byte writes,
not a single word write. As it stands, it does nothing.
- Some devices with sx150x expanders installed have their NRESET pins
ganged on the same line, so resetting one causes the others to reset -
not a nice thing to do arbitrarily!
- The probe, usually taking place at boot, implies a recent hard-reset,
so a software reset at this point is just a waste of energy anyway.
Therefore, make it optional, defaulting to off, as this will match the
common case of probing at powerup and also matches the current broken
no-op behavior.
Signed-off-by: Gregory Bean <gbean@codeaurora.org>
Reviewed-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/gpio/sx150x.c b/drivers/gpio/sx150x.c
index b42f42c..823559a 100644
--- a/drivers/gpio/sx150x.c
+++ b/drivers/gpio/sx150x.c
@@ -459,16 +459,32 @@
return err;
}
+static int sx150x_reset(struct sx150x_chip *chip)
+{
+ int err;
+
+ err = i2c_smbus_write_byte_data(chip->client,
+ chip->dev_cfg->reg_reset,
+ 0x12);
+ if (err < 0)
+ return err;
+
+ err = i2c_smbus_write_byte_data(chip->client,
+ chip->dev_cfg->reg_reset,
+ 0x34);
+ return err;
+}
+
static int sx150x_init_hw(struct sx150x_chip *chip,
struct sx150x_platform_data *pdata)
{
int err = 0;
- err = i2c_smbus_write_word_data(chip->client,
- chip->dev_cfg->reg_reset,
- 0x3412);
- if (err < 0)
- return err;
+ if (pdata->reset_during_probe) {
+ err = sx150x_reset(chip);
+ if (err < 0)
+ return err;
+ }
err = sx150x_i2c_write(chip->client,
chip->dev_cfg->reg_misc,
diff --git a/include/linux/i2c/sx150x.h b/include/linux/i2c/sx150x.h
index ee3049c..52baa79 100644
--- a/include/linux/i2c/sx150x.h
+++ b/include/linux/i2c/sx150x.h
@@ -63,6 +63,9 @@
* IRQ lines will appear. Similarly to gpio_base, the expander
* will create a block of irqs beginning at this number.
* This value is ignored if irq_summary is < 0.
+ * @reset_during_probe: If set to true, the driver will trigger a full
+ * reset of the chip at the beginning of the probe
+ * in order to place it in a known state.
*/
struct sx150x_platform_data {
unsigned gpio_base;
@@ -73,6 +76,7 @@
u16 io_polarity;
int irq_summary;
unsigned irq_base;
+ bool reset_during_probe;
};
#endif /* __LINUX_I2C_SX150X_H */