Hi Guennadi,
thanks for the patches and sorry for the delay.
I've tested them a few minutes ago and they are working fine.
2 minor things/questions:
1.) Why not always balance v4l2_clk_enable/disable() calls ?
2.) For someone who reads the code it likely looks a bit odd that if the
flag "unbalanced_power" is set, soc_camera balances
v4l2_clk_enable/disable but not power on/off calls (ssdd->power() calls).
So maybe "balance_clk" or "clk_balancing_needed" would be a better name
for the flag ?
Ok, let's summarize what we need:
- the 3 fake clock patches patches
- em28xx patch "make sure that all subdevices are powered on when needed"
- these 2 patches
All patches need to marked for stable (3.11).
Can you pick up my me28xx patch and send Mauro a pull request ?
Regards,
Frank
Am 21.10.2013 11:28, schrieb Guennadi Liakhovetski:
> Some non soc-camera drivers, e.g. em28xx, use subdevice drivers, originally
> written for soc-camera, which use soc_camera_power_on() and
> soc_camera_power_off() helpers to implement their .s_power() methods. Those
> helpers in turn can enable and disable a clock, if it is supplied to them
> as a parameter. This works well when camera host drivers balance their
> calls to subdevices' .s_power() methods. However, some such drivers fail to
> do that, which leads to unbalanced calls to v4l2_clk_enable() /
> v4l2_clk_disable(), which then in turn produce kernel warnings. Such
> behaviour is wrong and should be fixed, however, sometimes it is difficult,
> because some of those drivers are rather old and use lots of subdevices,
> which all should be tested after such a fix. To support such drivers this
> patch adds a work-around, allowing host drivers or platforms to set a flag,
> in which case soc-camera helpers will only enable the clock, if it is
> disabled, and disable it only once on the first call to .s_power(0).
>
> Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
> ---
>
> As promised yesterday, this is an alternative approach to fixing the
> em28xx problem, compile tested only.
>
> drivers/media/platform/soc_camera/soc_camera.c | 22 ++++++++++++++++------
> include/media/soc_camera.h | 14 ++++++++++++++
> 2 files changed, 30 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/media/platform/soc_camera/soc_camera.c b/drivers/media/platform/soc_camera/soc_camera.c
> index 387a232..21136a2 100644
> --- a/drivers/media/platform/soc_camera/soc_camera.c
> +++ b/drivers/media/platform/soc_camera/soc_camera.c
> @@ -71,11 +71,21 @@ static int video_dev_create(struct soc_camera_device *icd);
> int soc_camera_power_on(struct device *dev, struct soc_camera_subdev_desc *ssdd,
> struct v4l2_clk *clk)
> {
> - int ret = clk ? v4l2_clk_enable(clk) : 0;
> - if (ret < 0) {
> - dev_err(dev, "Cannot enable clock: %d\n", ret);
> - return ret;
> + int ret;
> + bool clock_toggle;
> +
> + if (clk && (!ssdd->unbalanced_power ||
> + !test_and_set_bit(0, &ssdd->clock_state))) {
> + ret = v4l2_clk_enable(clk);
> + if (ret < 0) {
> + dev_err(dev, "Cannot enable clock: %d\n", ret);
> + return ret;
> + }
> + clock_toggle = true;
> + } else {
> + clock_toggle = false;
> }
> +
> ret = regulator_bulk_enable(ssdd->num_regulators,
> ssdd->regulators);
> if (ret < 0) {
> @@ -98,7 +108,7 @@ epwron:
> regulator_bulk_disable(ssdd->num_regulators,
> ssdd->regulators);
> eregenable:
> - if (clk)
> + if (clock_toggle)
> v4l2_clk_disable(clk);
>
> return ret;
> @@ -127,7 +137,7 @@ int soc_camera_power_off(struct device *dev, struct soc_camera_subdev_desc *ssdd
> ret = ret ? : err;
> }
>
> - if (clk)
> + if (clk && (!ssdd->unbalanced_power || test_and_clear_bit(0, &ssdd->clock_state)))
> v4l2_clk_disable(clk);
>
> return ret;
> diff --git a/include/media/soc_camera.h b/include/media/soc_camera.h
> index 34d2414..5678a39 100644
> --- a/include/media/soc_camera.h
> +++ b/include/media/soc_camera.h
> @@ -150,6 +150,15 @@ struct soc_camera_subdev_desc {
> struct regulator_bulk_data *regulators;
> int num_regulators;
>
> + /*
> + * Set unbalanced_power to true to deal with legacy drivers, failing to
> + * balance their calls to subdevice's .s_power() method. clock_state is
> + * then used internally by helper functions, it shouldn't be touched by
> + * drivers or the platform code.
> + */
> + bool unbalanced_power;
> + unsigned long clock_state;
> +
> /* Optional callbacks to power on or off and reset the sensor */
> int (*power)(struct device *, int);
> int (*reset)(struct device *);
> @@ -206,6 +215,11 @@ struct soc_camera_link {
> struct regulator_bulk_data *regulators;
> int num_regulators;
>
> + /* Set by platforms to handle misbehaving drivers */
> + bool unbalanced_power;
> + /* Used by soc-camera helper functions */
> + unsigned long clock_state;
> +
> /* Optional callbacks to power on or off and reset the sensor */
> int (*power)(struct device *, int);
> int (*reset)(struct device *);
--
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