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Message-ID: <CAPY8ntA8V+816=UwaDa7Y-8vccPNfOoLQUvkQbC6KAtDZ0QxKw@mail.gmail.com>
Date: Mon, 2 Sep 2024 19:10:19 +0100
From: Dave Stevenson <dave.stevenson@...pberrypi.com>
To: bbara93@...il.com
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
Sakari Ailus <sakari.ailus@...ux.intel.com>, Hans de Goede <hdegoede@...hat.com>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Alexander Stein <alexander.stein@...tq-group.com>, linux-media@...r.kernel.org,
linux-kernel@...r.kernel.org, Benjamin Bara <benjamin.bara@...data.com>
Subject: Re: [PATCH v3 7/7] media: i2c: imx290: Implement a "privacy mode" for probe()
Hi Benjamin
On Mon, 2 Sept 2024 at 16:59, <bbara93@...il.com> wrote:
>
> From: Benjamin Bara <benjamin.bara@...data.com>
>
> Currently, we have a trade-off between potentially enabling the privacy
> LED and reading out the connection state of the sensor during probe().
>
> To have a somewhat defined policy for now, make a decision based on the
> power supplies of the sensor. If they are enabled anyways, communicate
> with the powered sensor for an availability check. Otherwise, create the
> subdevice without knowing whether the sensor is connected or not.
Almost all the camera modules used on Raspberry Pi have regulators
controlled via a GPIO, but no privacy LED. The preference from us is
very definitely to query the sensor during probe where possible to
flag up any connectivity issues, and indeed I've had a number of
support threads with imx290 where it's just not been connected but it
probed fully and showed up in libcamera.
How can I opt in to patch 6 checking basic I2C to the sensor during
probe when I have a controllable regulator? (This is where the
discussions over a dtbinding for privacy LEDs and not powering up
sensors during probe comes in).
Thanks
Dave
> Signed-off-by: Benjamin Bara <benjamin.bara@...data.com>
> ---
> Changes since v2:
> - new
> ---
> drivers/media/i2c/imx290.c | 82 ++++++++++++++++++++++++++++++++--------------
> 1 file changed, 57 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/media/i2c/imx290.c b/drivers/media/i2c/imx290.c
> index 6b292bbb0856..338b2c5ea547 100644
> --- a/drivers/media/i2c/imx290.c
> +++ b/drivers/media/i2c/imx290.c
> @@ -1354,6 +1354,17 @@ static void imx290_subdev_cleanup(struct imx290 *imx290)
> * Power management
> */
>
> +static bool is_imx290_power_on(struct imx290 *imx)
> +{
> + unsigned int i;
> +
> + for (i = 0; i < ARRAY_SIZE(imx->supplies); i++)
> + if (!regulator_is_enabled(imx->supplies[i].consumer))
> + return false;
> +
> + return true;
> +}
> +
> static int imx290_power_on(struct imx290 *imx290)
> {
> int ret;
> @@ -1571,6 +1582,7 @@ static int imx290_probe(struct i2c_client *client)
> {
> struct device *dev = &client->dev;
> struct imx290 *imx290;
> + bool power_on;
> u64 val;
> int ret;
>
> @@ -1611,36 +1623,54 @@ static int imx290_probe(struct i2c_client *client)
> return ret;
>
> /*
> - * Enable power management. The driver supports runtime PM, but needs to
> - * work when runtime PM is disabled in the kernel. To that end, power
> - * the sensor on manually here.
> + * Privacy mode: if the regulators are not enabled, avoid enabling them.
> + * In case the regulators are enabled, we still want to make sure that
> + * the regulators know that they have another consumer, therefore run
> + * the powering sequence.
> */
> - ret = imx290_power_on(imx290);
> - if (ret < 0) {
> - dev_err(dev, "Could not power on the device\n");
> - return ret;
> + power_on = is_imx290_power_on(imx290);
> + dev_dbg(dev, "%s: power on: %d\n", __func__, power_on);
> + if (power_on) {
> + /*
> + * Enable power management. The driver supports runtime PM, but
> + * needs to work when runtime PM is disabled in the kernel. To
> + * that end, power the sensor on manually here.
> + */
> + ret = imx290_power_on(imx290);
> + if (ret < 0) {
> + dev_err(dev, "Could not power on the device\n");
> + return ret;
> + }
> +
> + /*
> + * Enable runtime PM with autosuspend. As the device has been
> + * powered manually, mark it as active, and increase the usage
> + * count without resuming the device.
> + */
> + pm_runtime_set_active(dev);
> + pm_runtime_get_noresume(dev);
> }
>
> - /*
> - * Enable runtime PM with autosuspend. As the device has been powered
> - * manually, mark it as active, and increase the usage count without
> - * resuming the device.
> - */
> - pm_runtime_set_active(dev);
> - pm_runtime_get_noresume(dev);
> pm_runtime_enable(dev);
> pm_runtime_set_autosuspend_delay(dev, 1000);
> pm_runtime_use_autosuspend(dev);
>
> - /* Make sure the sensor is available before V4L2 subdev init. */
> - ret = cci_read(imx290->regmap, IMX290_STANDBY, &val, NULL);
> - if (ret) {
> - ret = dev_err_probe(dev, -ENODEV, "Failed to detect sensor\n");
> - goto err_pm;
> - }
> - if (val != IMX290_STANDBY_STANDBY) {
> - ret = dev_err_probe(dev, -ENODEV, "Sensor is not in standby\n");
> - goto err_pm;
> + /*
> + * Make sure the sensor is available before V4L2 subdev init.
> + * This only works when the sensor is powered.
> + */
> + if (power_on) {
> + ret = cci_read(imx290->regmap, IMX290_STANDBY, &val, NULL);
> + if (ret) {
> + ret = dev_err_probe(dev, -ENODEV,
> + "Failed to detect sensor\n");
> + goto err_pm;
> + }
> + if (val != IMX290_STANDBY_STANDBY) {
> + ret = dev_err_probe(dev, -ENODEV,
> + "Sensor is not in standby\n");
> + goto err_pm;
> + }
> }
>
> /* Initialize the V4L2 subdev. */
> @@ -1666,8 +1696,10 @@ static int imx290_probe(struct i2c_client *client)
> * Decrease the PM usage count. The device will get suspended after the
> * autosuspend delay, turning the power off.
> */
> - pm_runtime_mark_last_busy(dev);
> - pm_runtime_put_autosuspend(dev);
> + if (power_on) {
> + pm_runtime_mark_last_busy(dev);
> + pm_runtime_put_autosuspend(dev);
> + }
>
> return 0;
>
>
> --
> 2.46.0
>
>
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