The patch titled
gpio: sx150x: correct and refine reset-on-probe behavior
has been added to the -mm tree. Its filename is
gpio-sx150x-correct-and-refine-reset-on-probe-behavior.patch
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------------------------------------------------------
Subject: gpio: sx150x: correct and refine reset-on-probe behavior
From: Gregory Bean <gbean@xxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxx>
Reviewed-by: Jean Delvare <khali@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/gpio/sx150x.c | 26 +++++++++++++++++++++-----
include/linux/i2c/sx150x.h | 4 ++++
2 files changed, 25 insertions(+), 5 deletions(-)
diff -puN drivers/gpio/sx150x.c~gpio-sx150x-correct-and-refine-reset-on-probe-behavior drivers/gpio/sx150x.c
--- a/drivers/gpio/sx150x.c~gpio-sx150x-correct-and-refine-reset-on-probe-behavior
+++ a/drivers/gpio/sx150x.c
@@ -459,17 +459,33 @@ static int sx150x_init_io(struct sx150x_
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);
diff -puN include/linux/i2c/sx150x.h~gpio-sx150x-correct-and-refine-reset-on-probe-behavior include/linux/i2c/sx150x.h
--- a/include/linux/i2c/sx150x.h~gpio-sx150x-correct-and-refine-reset-on-probe-behavior
+++ a/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 @@ struct sx150x_platform_data {
u16 io_polarity;
int irq_summary;
unsigned irq_base;
+ bool reset_during_probe;
};
#endif /* __LINUX_I2C_SX150X_H */
_
Patches currently in -mm which might be from gbean@xxxxxxxxxxxxxx are
gpio-sx150x-correct-and-refine-reset-on-probe-behavior.patch
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