media: i2c: dw9719: Fix power on/off sequence

The "jiggle" code was not actually expecting failure, which it should
because that's what actually happens when the device wasn't already woken
up by the regulator power-on (i.e. in the case of a shared regulator).

Also, do actually enter the internal suspend mode on shutdown, to save
power in the case of a shared regulator.

Also, wait a bit longer (2x tOPR) on waking up, 1x is not enough at least
on the DW9718S as found on the motorola-nora smartphone.

Signed-off-by: Val Packett <val@packett.cool>
Signed-off-by: André Apitzsch <git@apitzsch.eu>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>

diff --git a/drivers/media/i2c/dw9719.c b/drivers/media/i2c/dw9719.c
index a24594523030df7df7fb60afb5248472b4a8ea13..3627e78b8b6668933c4ecd92231465ce4105ff0c 100644 (file)
--- a/drivers/media/i2c/dw9719.c
+++ b/drivers/media/i2c/dw9719.c
@@ -95,12 +95,20 @@ struct dw9719_device {
 
 static int dw9719_power_down(struct dw9719_device *dw9719)
 {
+       u32 reg_pwr = dw9719->model == DW9718S ? DW9718S_PD : DW9719_CONTROL;
+
+       /*
+        * Worth engaging the internal SHUTDOWN mode especially due to the
+        * regulator being potentially shared with other devices.
+        */
+       if (cci_write(dw9719->regmap, reg_pwr, DW9719_SHUTDOWN, NULL))
+               dev_err(dw9719->dev, "Error writing to power register\n");
        return regulator_disable(dw9719->regulator);
 }
 
 static int dw9719_power_up(struct dw9719_device *dw9719, bool detect)
 {
-       u32 reg_pwr;
+       u32 reg_pwr = dw9719->model == DW9718S ? DW9718S_PD : DW9719_CONTROL;
        u64 val;
        int ret;
        int err;
@@ -109,13 +117,17 @@ static int dw9719_power_up(struct dw9719_device *dw9719, bool detect)
        if (ret)
                return ret;
 
-       /* Jiggle SCL pin to wake up device */
-       reg_pwr = dw9719->model == DW9718S ? DW9718S_PD : DW9719_CONTROL;
-       cci_write(dw9719->regmap, reg_pwr, DW9719_SHUTDOWN, &ret);
-       fsleep(100);
+       /*
+        * Need 100us to transition from SHUTDOWN to STANDBY.
+        * Jiggle the SCL pin to wake up the device (even when the regulator is
+        * shared) and wait double the time to be sure, as 100us is not enough
+        * at least on the DW9718S as found on the motorola-nora smartphone,
+        * then retry the write.
+        */
+       cci_write(dw9719->regmap, reg_pwr, DW9719_STANDBY, NULL);
+       /* the jiggle is expected to fail, don't even log that as error */
+       fsleep(200);
        cci_write(dw9719->regmap, reg_pwr, DW9719_STANDBY, &ret);
-       /* Need 100us to transit from SHUTDOWN to STANDBY */
-       fsleep(100);
 
        if (detect) {
                /* This model does not have an INFO register */