Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx> wrote on Mon [2019-Sep-30 10:28:57 +0300]:
> Hi Benoit,
>
> On Fri, Sep 27, 2019 at 01:47:20PM -0500, Benoit Parrot wrote:
> > On some board it is possible that the sensor 'powerdown' and or 'reset'
> > pin might be controlled by gpio instead of being tied.
> >
> > To implement we add pm_runtime support which will handle the power
> > up/down sequence when it is available otherwise the sensor will be
> > powered on at module insertion/probe and powered off at module removal.
> >
> > Now originally the driver assumed that the sensor would always stay
> > powered and keep its register setting. We cannot assume this anymore, so
> > every time we "power up" we need to re-program the initial registers
> > configuration first. This was previously done only at probe time.
> >
> > Signed-off-by: Benoit Parrot <bparrot@xxxxxx>
> > ---
> > drivers/media/i2c/Kconfig | 2 +-
> > drivers/media/i2c/ov2659.c | 88 +++++++++++++++++++++++++++++++++++++-
> > 2 files changed, 87 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> > index 7eee1812bba3..315c1d8bdb7b 100644
> > --- a/drivers/media/i2c/Kconfig
> > +++ b/drivers/media/i2c/Kconfig
> > @@ -634,7 +634,7 @@ config VIDEO_OV2640
> > config VIDEO_OV2659
> > tristate "OmniVision OV2659 sensor support"
> > depends on VIDEO_V4L2 && I2C
> > - depends on MEDIA_CAMERA_SUPPORT
> > + depends on MEDIA_CAMERA_SUPPORT && GPIOLIB
> > select V4L2_FWNODE
> > help
> > This is a Video4Linux2 sensor driver for the OmniVision
> > diff --git a/drivers/media/i2c/ov2659.c b/drivers/media/i2c/ov2659.c
> > index cd4625432264..7d0baa386644 100644
> > --- a/drivers/media/i2c/ov2659.c
> > +++ b/drivers/media/i2c/ov2659.c
> > @@ -22,9 +22,11 @@
> >
> > #include <linux/clk.h>
> > #include <linux/delay.h>
> > +#include <linux/gpio/consumer.h>
> > #include <linux/i2c.h>
> > #include <linux/module.h>
> > #include <linux/of_graph.h>
> > +#include <linux/pm_runtime.h>
> >
> > #include <media/i2c/ov2659.h>
> > #include <media/v4l2-ctrls.h>
> > @@ -218,6 +220,11 @@ struct ov2659 {
> > struct sensor_register *format_ctrl_regs;
> > struct ov2659_pll_ctrl pll;
> > int streaming;
> > + /* used to control the sensor PWDN pin */
> > + struct gpio_desc *pwdn_gpio;
> > + /* used to control the sensor RESETB pin */
> > + struct gpio_desc *resetb_gpio;
> > + int on;
>
> Please use runtime PM for this instead. It's hard to get this right
> otherwise.
So you mean, I should use the "if (!pm_runtime_get_if_in_use(dev))"
construct?
Ok I'll switch it to that, just using "on" was a little simple but I
already had it :).
>
> Access to "on" is not serialised with the power state changes. In this case
> e.g. drivers/media/i2c/ov5670.c is a good example. I think I'll see how I
> could improve smiapp as well.
Ok so that driver uses this pm method but does not actually power up or
down the sensor.
Benoit
>
> --
> Sakari Ailus
> sakari.ailus@xxxxxxxxxxxxxxx
