On Sat Sep 20 14:03:47 2025 +0200, Val Packett wrote:
> 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 <[email protected]>
> Signed-off-by: André Apitzsch <[email protected]>
> Signed-off-by: Sakari Ailus <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/i2c/dw9719.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
---
diff --git a/drivers/media/i2c/dw9719.c b/drivers/media/i2c/dw9719.c
index a24594523030..3627e78b8b66 100644
--- 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 */
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