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| author | Gregory Bean <gbean@codeaurora.org> | 2010-09-09 16:38:02 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-09-09 18:57:24 -0700 |
| commit | 5affb607720d734ca572b8a77c5c7d62d3042b6f (patch) | |
| tree | 5c3a675bef03570958fc4e9baffb318ec7f64e31 /drivers/gpio | |
| parent | 0dcc48c15f63ee86c2fcd33968b08d651f0360a5 (diff) | |
| download | linux-5affb607720d734ca572b8a77c5c7d62d3042b6f.tar.gz linux-5affb607720d734ca572b8a77c5c7d62d3042b6f.tar.bz2 linux-5affb607720d734ca572b8a77c5c7d62d3042b6f.zip | |
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>
Diffstat (limited to 'drivers/gpio')
| -rw-r--r-- | drivers/gpio/sx150x.c | 26 |
1 files changed, 21 insertions, 5 deletions
diff --git a/drivers/gpio/sx150x.c b/drivers/gpio/sx150x.c index b42f42ca70c3..823559ab0e24 100644 --- a/drivers/gpio/sx150x.c +++ b/drivers/gpio/sx150x.c @@ -459,17 +459,33 @@ static int sx150x_init_io(struct sx150x_chip *chip, u8 base, u16 cfg) return err; } -static int sx150x_init_hw(struct sx150x_chip *chip, - struct sx150x_platform_data *pdata) +static int sx150x_reset(struct sx150x_chip *chip) { - 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, - 0x3412); + 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; + + 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, 0x01); |