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Message-ID: <72352182-66ac-121e-ab09-da52af1b7581@ideasonboard.com>
Date: Fri, 28 May 2021 09:44:45 +0300
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Pratyush Yadav <p.yadav@...com>,
Maxime Ripard <mripard@...nel.org>,
Mauro Carvalho Chehab <mchehab@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Kishon Vijay Abraham I <kishon@...com>,
Vinod Koul <vkoul@...nel.org>,
Peter Ujfalusi <peter.ujfalusi@...il.com>,
Steve Longerbeam <slongerbeam@...il.com>,
Benoit Parrot <bparrot@...com>, linux-media@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-phy@...ts.infradead.org, dmaengine@...r.kernel.org
Cc: Vignesh Raghavendra <vigneshr@...com>,
Chunfeng Yun <chunfeng.yun@...iatek.com>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>
Subject: Re: [PATCH v2 05/18] media: ov5640: Use runtime PM to control sensor
power
On 26/05/2021 18:22, Pratyush Yadav wrote:
> Calling s_power subdev callback is discouraged. Instead, the subdevs
> should use runtime PM to control its power. Use runtime PM callbacks to
> control sensor power. The pm counter is incremented when the stream is
> started and decremented when the stream is stopped.
>
> Refactor s_stream() a bit to make this new control flow easier. Add a
> helper to choose whether mipi or dvp set_stream needs to be called. The
> logic flow is also changed to make it a bit clearer.
>
> Signed-off-by: Pratyush Yadav <p.yadav@...com>
>
> ---
>
> Changes in v2:
> - New in v2.
>
> drivers/media/i2c/Kconfig | 2 +-
> drivers/media/i2c/ov5640.c | 124 +++++++++++++++++++++++--------------
> 2 files changed, 77 insertions(+), 49 deletions(-)
>
> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
> index 462c0e059754..5588fc1cc14a 100644
> --- a/drivers/media/i2c/Kconfig
> +++ b/drivers/media/i2c/Kconfig
> @@ -914,7 +914,7 @@ config VIDEO_OV2740
>
> config VIDEO_OV5640
> tristate "OmniVision OV5640 sensor support"
> - depends on OF
> + depends on OF && PM
> depends on GPIOLIB && VIDEO_V4L2 && I2C
> select MEDIA_CONTROLLER
> select VIDEO_V4L2_SUBDEV_API
> diff --git a/drivers/media/i2c/ov5640.c b/drivers/media/i2c/ov5640.c
> index 5b9cc71df473..4ed5758e2398 100644
> --- a/drivers/media/i2c/ov5640.c
> +++ b/drivers/media/i2c/ov5640.c
> @@ -15,6 +15,7 @@
> #include <linux/init.h>
> #include <linux/module.h>
> #include <linux/of_device.h>
> +#include <linux/pm_runtime.h>
> #include <linux/regulator/consumer.h>
> #include <linux/slab.h>
> #include <linux/types.h>
> @@ -238,8 +239,6 @@ struct ov5640_dev {
> /* lock to protect all members below */
> struct mutex lock;
>
> - int power_count;
> -
> struct v4l2_mbus_framefmt fmt;
> bool pending_fmt_change;
>
> @@ -1277,6 +1276,14 @@ static int ov5640_set_stream_mipi(struct ov5640_dev *sensor, bool on)
> on ? 0x00 : 0x0f);
> }
>
> +static int ov5640_set_stream(struct ov5640_dev *sensor, bool on)
> +{
> + if (sensor->ep.bus_type == V4L2_MBUS_CSI2_DPHY)
> + return ov5640_set_stream_mipi(sensor, on);
> + else
> + return ov5640_set_stream_dvp(sensor, on);
> +}
> +
> static int ov5640_get_sysclk(struct ov5640_dev *sensor)
> {
> /* calculate sysclk */
> @@ -2155,37 +2162,6 @@ static int ov5640_set_power(struct ov5640_dev *sensor, bool on)
>
> /* --------------- Subdev Operations --------------- */
>
> -static int ov5640_s_power(struct v4l2_subdev *sd, int on)
> -{
> - struct ov5640_dev *sensor = to_ov5640_dev(sd);
> - int ret = 0;
> -
> - mutex_lock(&sensor->lock);
> -
> - /*
> - * If the power count is modified from 0 to != 0 or from != 0 to 0,
> - * update the power state.
> - */
> - if (sensor->power_count == !on) {
> - ret = ov5640_set_power(sensor, !!on);
> - if (ret)
> - goto out;
> - }
> -
> - /* Update the power count. */
> - sensor->power_count += on ? 1 : -1;
> - WARN_ON(sensor->power_count < 0);
> -out:
> - mutex_unlock(&sensor->lock);
> -
> - if (on && !ret && sensor->power_count == 1) {
> - /* restore controls */
> - ret = v4l2_ctrl_handler_setup(&sensor->ctrls.handler);
> - }
> -
> - return ret;
> -}
> -
> static int ov5640_try_frame_interval(struct ov5640_dev *sensor,
> struct v4l2_fract *fi,
> u32 width, u32 height)
> @@ -2681,6 +2657,7 @@ static int ov5640_s_ctrl(struct v4l2_ctrl *ctrl)
> {
> struct v4l2_subdev *sd = ctrl_to_sd(ctrl);
> struct ov5640_dev *sensor = to_ov5640_dev(sd);
> + struct device *dev = &sensor->i2c_client->dev;
> int ret;
>
> /* v4l2_ctrl_lock() locks our own mutex */
> @@ -2690,7 +2667,7 @@ static int ov5640_s_ctrl(struct v4l2_ctrl *ctrl)
> * not apply any controls to H/W at this time. Instead
> * the controls will be restored right after power-up.
> */
> - if (sensor->power_count == 0)
> + if (pm_runtime_suspended(dev))
> return 0;
>
> switch (ctrl->id) {
> @@ -2939,39 +2916,56 @@ static int ov5640_enum_mbus_code(struct v4l2_subdev *sd,
> static int ov5640_s_stream(struct v4l2_subdev *sd, int enable)
> {
> struct ov5640_dev *sensor = to_ov5640_dev(sd);
> + struct device *dev = &sensor->i2c_client->dev;
> int ret = 0;
>
> mutex_lock(&sensor->lock);
>
> - if (sensor->streaming == !enable) {
> - if (enable && sensor->pending_mode_change) {
> + if (sensor->streaming == enable)
> + goto out;
> +
> + if (enable) {
> + ret = pm_runtime_get_sync(dev);
> + if (ret < 0) {
> + pm_runtime_put_noidle(dev);
> + goto out;
> + }
There now seems to be a function to do the above steps:
pm_runtime_resume_and_get.
> +
> + if (sensor->pending_mode_change) {
> ret = ov5640_set_mode(sensor);
> if (ret)
> - goto out;
> + goto put_pm;
> }
>
> - if (enable && sensor->pending_fmt_change) {
> + if (sensor->pending_fmt_change) {
> ret = ov5640_set_framefmt(sensor, &sensor->fmt);
> if (ret)
> - goto out;
> + goto put_pm;
> sensor->pending_fmt_change = false;
> }
>
> - if (sensor->ep.bus_type == V4L2_MBUS_CSI2_DPHY)
> - ret = ov5640_set_stream_mipi(sensor, enable);
> - else
> - ret = ov5640_set_stream_dvp(sensor, enable);
> + ret = ov5640_set_stream(sensor, enable);
> + if (ret)
> + goto put_pm;
> + } else {
> + ret = ov5640_set_stream(sensor, enable);
Instead of using "enable" here (and in the enable path above), just use
true/false. It'll be more readable.
> + if (ret)
> + goto out;
>
> - if (!ret)
> - sensor->streaming = enable;
> + pm_runtime_put(dev);
> }
> +
> + sensor->streaming = enable;
> + goto out;
> +
> +put_pm:
> + pm_runtime_put(dev);
> out:
> mutex_unlock(&sensor->lock);
> return ret;
> }
The flow in the above function is quite confusing. I think you should
either 1) have a separate error paths via gotos and a return 0 before
the error labels, or 2) common error and success path, without that
final "goto out" you have above.
Maybe if you move the code in the "if (enable) {} else {}" to the
ov5640_set_stream(), the flow will be easier to manage.
>
> static const struct v4l2_subdev_core_ops ov5640_core_ops = {
> - .s_power = ov5640_s_power,
> .log_status = v4l2_ctrl_subdev_log_status,
> .subscribe_event = v4l2_ctrl_subdev_subscribe_event,
> .unsubscribe_event = v4l2_event_subdev_unsubscribe,
> @@ -3037,6 +3031,29 @@ static int ov5640_check_chip_id(struct ov5640_dev *sensor)
> return ret;
> }
>
> +static int ov5640_suspend(struct device *dev)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct v4l2_subdev *subdev = i2c_get_clientdata(client);
> + struct ov5640_dev *sensor = to_ov5640_dev(subdev);
> +
> + return ov5640_set_power(sensor, false);
> +}
> +
> +static int ov5640_resume(struct device *dev)
> +{
> + struct i2c_client *client = to_i2c_client(dev);
> + struct v4l2_subdev *subdev = i2c_get_clientdata(client);
> + struct ov5640_dev *sensor = to_ov5640_dev(subdev);
> + int ret = 0;
> +
> + ret = ov5640_set_power(sensor, true);
> + if (ret)
> + return ret;
> +
> + return __v4l2_ctrl_handler_setup(&sensor->ctrls.handler);
> +}
> +
> static int ov5640_probe(struct i2c_client *client)
> {
> struct device *dev = &client->dev;
> @@ -3162,13 +3179,17 @@ static int ov5640_probe(struct i2c_client *client)
> if (ret)
> goto entity_cleanup;
>
> + pm_runtime_enable(dev);
> + pm_runtime_set_suspended(dev);
> +
> ret = v4l2_async_register_subdev_sensor(&sensor->sd);
> if (ret)
> - goto free_ctrls;
> + goto error_pm;
>
> return 0;
>
> -free_ctrls:
> +error_pm:
> + pm_runtime_disable(dev);
The label style used here seems to be the
"label-tells-what-will-be-done", so I think instead of "error_pm", it
should be, perhaps, "pm_disable".
> v4l2_ctrl_handler_free(&sensor->ctrls.handler);
> entity_cleanup:
> media_entity_cleanup(&sensor->sd.entity);
> @@ -3178,17 +3199,23 @@ static int ov5640_probe(struct i2c_client *client)
>
> static int ov5640_remove(struct i2c_client *client)
> {
> + struct device *dev = &client->dev;
> struct v4l2_subdev *sd = i2c_get_clientdata(client);
> struct ov5640_dev *sensor = to_ov5640_dev(sd);
>
> v4l2_async_unregister_subdev(&sensor->sd);
> media_entity_cleanup(&sensor->sd.entity);
> + pm_runtime_disable(dev);
> v4l2_ctrl_handler_free(&sensor->ctrls.handler);
> mutex_destroy(&sensor->lock);
>
> return 0;
> }
>
> +static const struct dev_pm_ops ov5640_pm_ops = {
> + SET_RUNTIME_PM_OPS(ov5640_suspend, ov5640_resume, NULL)
> +};
> +
> static const struct i2c_device_id ov5640_id[] = {
> {"ov5640", 0},
> {},
> @@ -3205,6 +3232,7 @@ static struct i2c_driver ov5640_i2c_driver = {
> .driver = {
> .name = "ov5640",
> .of_match_table = ov5640_dt_ids,
> + .pm = &ov5640_pm_ops,
> },
> .id_table = ov5640_id,
> .probe_new = ov5640_probe,
>
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