Commit 5affb607 authored by Gregory Bean's avatar Gregory Bean Committed by Linus Torvalds

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: default avatarGregory Bean <gbean@codeaurora.org>
Reviewed-by: default avatarJean Delvare <khali@linux-fr.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0dcc48c1
...@@ -459,17 +459,33 @@ static int sx150x_init_io(struct sx150x_chip *chip, u8 base, u16 cfg) ...@@ -459,17 +459,33 @@ static int sx150x_init_io(struct sx150x_chip *chip, u8 base, u16 cfg)
return err; return err;
} }
static int sx150x_init_hw(struct sx150x_chip *chip, static int sx150x_reset(struct sx150x_chip *chip)
struct sx150x_platform_data *pdata)
{ {
int err = 0; int err;
err = i2c_smbus_write_word_data(chip->client, err = i2c_smbus_write_byte_data(chip->client,
chip->dev_cfg->reg_reset, chip->dev_cfg->reg_reset,
0x3412); 0x12);
if (err < 0) if (err < 0)
return err; 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;
if (pdata->reset_during_probe) {
err = sx150x_reset(chip);
if (err < 0)
return err;
}
err = sx150x_i2c_write(chip->client, err = sx150x_i2c_write(chip->client,
chip->dev_cfg->reg_misc, chip->dev_cfg->reg_misc,
0x01); 0x01);
......
...@@ -63,6 +63,9 @@ ...@@ -63,6 +63,9 @@
* IRQ lines will appear. Similarly to gpio_base, the expander * IRQ lines will appear. Similarly to gpio_base, the expander
* will create a block of irqs beginning at this number. * will create a block of irqs beginning at this number.
* This value is ignored if irq_summary is < 0. * 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 { struct sx150x_platform_data {
unsigned gpio_base; unsigned gpio_base;
...@@ -73,6 +76,7 @@ struct sx150x_platform_data { ...@@ -73,6 +76,7 @@ struct sx150x_platform_data {
u16 io_polarity; u16 io_polarity;
int irq_summary; int irq_summary;
unsigned irq_base; unsigned irq_base;
bool reset_during_probe;
}; };
#endif /* __LINUX_I2C_SX150X_H */ #endif /* __LINUX_I2C_SX150X_H */
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