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Message-ID: <a4bba302-8be2-4bbd-96c8-3a20472e0c12@ideasonboard.com>
Date: Mon, 1 Dec 2025 15:11:29 +0200
From: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To: Rishikesh Donadkar <r-donadkar@...com>, jai.luthra@...ux.dev,
laurent.pinchart@...asonboard.com, mripard@...nel.org
Cc: y-abhilashchandra@...com, devarsht@...com, s-jain1@...com,
vigneshr@...com, mchehab@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
p.zabel@...gutronix.de, conor+dt@...nel.org, sakari.ailus@...ux.intel.com,
hverkuil-cisco@...all.nl, jai.luthra@...asonboard.com,
changhuang.liang@...rfivetech.com, jack.zhu@...rfivetech.com,
sjoerd@...labora.com, dan.carpenter@...aro.org, hverkuil+cisco@...nel.org,
linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
devicetree@...r.kernel.org
Subject: Re: [PATCH v8 16/18] media: cadence: csi2rx: Support runtime PM
Hi,
On 12/11/2025 13:54, Rishikesh Donadkar wrote:
> From: Changhuang Liang <changhuang.liang@...rfivetech.com>
>
> Use runtime power management hooks to save power when CSI-RX is not in
> use.
>
> Signed-off-by: Changhuang Liang <changhuang.liang@...rfivetech.com>
> Tested-by: Rishikesh Donadkar <r-donadkar@...com>
> Reviewed-by: Rishikesh Donadkar <r-donadkar@...com>
> Signed-off-by: Jai Luthra <jai.luthra@...asonboard.com>
> Signed-off-by: Rishikesh Donadkar <r-donadkar@...com>
> ---
> drivers/media/platform/cadence/Kconfig | 1 +
> drivers/media/platform/cadence/cdns-csi2rx.c | 129 ++++++++++++-------
> 2 files changed, 83 insertions(+), 47 deletions(-)
>
> diff --git a/drivers/media/platform/cadence/Kconfig b/drivers/media/platform/cadence/Kconfig
> index 1aa608c00dbce..ea85ef82760e6 100644
> --- a/drivers/media/platform/cadence/Kconfig
> +++ b/drivers/media/platform/cadence/Kconfig
> @@ -5,6 +5,7 @@ comment "Cadence media platform drivers"
> config VIDEO_CADENCE_CSI2RX
> tristate "Cadence MIPI-CSI2 RX Controller"
> depends on VIDEO_DEV
> + depends on PM
> select MEDIA_CONTROLLER
> select VIDEO_V4L2_SUBDEV_API
> select V4L2_FWNODE
> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> index 833bc134f17cb..6447c225ba354 100644
> --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> @@ -337,11 +337,6 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
> u32 reg;
> int ret;
>
> - ret = clk_prepare_enable(csi2rx->p_clk);
> - if (ret)
> - return ret;
> -
> - reset_control_deassert(csi2rx->p_rst);
> csi2rx_reset(csi2rx);
>
> if (csi2rx->error_irq >= 0)
> @@ -382,7 +377,7 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
> if (ret) {
> dev_err(csi2rx->dev,
> "Failed to configure external DPHY: %d\n", ret);
> - goto err_disable_pclk;
> + return ret;
> }
> }
>
> @@ -397,12 +392,6 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
> * hence the reference counting.
> */
> for (i = 0; i < csi2rx->max_streams; i++) {
> - ret = clk_prepare_enable(csi2rx->pixel_clk[i]);
> - if (ret)
> - goto err_disable_pixclk;
> -
> - reset_control_deassert(csi2rx->pixel_rst[i]);
> -
> writel(CSI2RX_STREAM_CFG_FIFO_MODE_LARGE_BUF |
> FIELD_PREP(CSI2RX_STREAM_CFG_NUM_PIXELS_MASK,
> csi2rx->num_pixels[i]),
> @@ -415,30 +404,8 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
> csi2rx->base + CSI2RX_STREAM_CTRL_REG(i));
> }
>
> - ret = clk_prepare_enable(csi2rx->sys_clk);
> - if (ret)
> - goto err_disable_pixclk;
> -
> - reset_control_deassert(csi2rx->sys_rst);
> -
> - clk_disable_unprepare(csi2rx->p_clk);
>
> return 0;
> -
> -err_disable_pixclk:
> - for (; i > 0; i--) {
> - reset_control_assert(csi2rx->pixel_rst[i - 1]);
> - clk_disable_unprepare(csi2rx->pixel_clk[i - 1]);
> - }
> -
> - if (csi2rx->dphy) {
> - writel(0, csi2rx->base + CSI2RX_DPHY_LANE_CTRL_REG);
> - phy_power_off(csi2rx->dphy);
> - }
> -err_disable_pclk:
> - clk_disable_unprepare(csi2rx->p_clk);
> -
> - return ret;
> }
>
> static void csi2rx_stop(struct csi2rx_priv *csi2rx)
> @@ -447,10 +414,6 @@ static void csi2rx_stop(struct csi2rx_priv *csi2rx)
> u32 val;
> int ret;
>
> - clk_prepare_enable(csi2rx->p_clk);
> - reset_control_assert(csi2rx->sys_rst);
> - clk_disable_unprepare(csi2rx->sys_clk);
> -
> writel(0, csi2rx->base + CSI2RX_ERROR_IRQS_MASK_REG);
>
> for (i = 0; i < csi2rx->max_streams; i++) {
> @@ -465,14 +428,8 @@ static void csi2rx_stop(struct csi2rx_priv *csi2rx)
> if (ret)
> dev_warn(csi2rx->dev,
> "Failed to stop streaming on pad%u\n", i);
> -
> - reset_control_assert(csi2rx->pixel_rst[i]);
> - clk_disable_unprepare(csi2rx->pixel_clk[i]);
> }
>
> - reset_control_assert(csi2rx->p_rst);
> - clk_disable_unprepare(csi2rx->p_clk);
> -
> if (csi2rx->dphy) {
> writel(0, csi2rx->base + CSI2RX_DPHY_LANE_CTRL_REG);
>
> @@ -548,10 +505,17 @@ static int csi2rx_enable_streams(struct v4l2_subdev *subdev,
> * enable the whole controller.
> */
> if (!csi2rx->count) {
> + ret = pm_runtime_resume_and_get(csi2rx->dev);
> + if (ret < 0)
> + return ret;
> +
> csi2rx_update_vc_select(csi2rx, state);
> +
> ret = csi2rx_start(csi2rx);
> - if (ret)
> + if (ret) {
> + pm_runtime_put(csi2rx->dev);
> return ret;
> + }
> }
>
> /* Start streaming on the source */
> @@ -561,8 +525,10 @@ static int csi2rx_enable_streams(struct v4l2_subdev *subdev,
> dev_err(csi2rx->dev,
> "Failed to start streams %#llx on subdev\n",
> sink_streams);
> - if (!csi2rx->count)
> + if (!csi2rx->count) {
> csi2rx_stop(csi2rx);
> + pm_runtime_put(csi2rx->dev);
Probably time to add 'goto' based error handling to this func... Maybe
in this patch, maybe as a separate patch before this.
Tomi
> + }
> return ret;
> }
>
> @@ -589,8 +555,10 @@ static int csi2rx_disable_streams(struct v4l2_subdev *subdev,
> csi2rx->count--;
>
> /* Let the last user turn off the lights. */
> - if (!csi2rx->count)
> + if (!csi2rx->count) {
> csi2rx_stop(csi2rx);
> + pm_runtime_put(csi2rx->dev);
> + }
>
> return 0;
> }
> @@ -1092,6 +1060,7 @@ static int csi2rx_probe(struct platform_device *pdev)
> if (ret)
> goto err_cleanup;
>
> + pm_runtime_enable(csi2rx->dev);
> ret = v4l2_async_register_subdev(&csi2rx->subdev);
> if (ret < 0)
> goto err_free_state;
> @@ -1106,6 +1075,7 @@ static int csi2rx_probe(struct platform_device *pdev)
>
> err_free_state:
> v4l2_subdev_cleanup(&csi2rx->subdev);
> + pm_runtime_disable(csi2rx->dev);
> err_cleanup:
> v4l2_async_nf_unregister(&csi2rx->notifier);
> v4l2_async_nf_cleanup(&csi2rx->notifier);
> @@ -1124,9 +1094,73 @@ static void csi2rx_remove(struct platform_device *pdev)
> v4l2_async_unregister_subdev(&csi2rx->subdev);
> v4l2_subdev_cleanup(&csi2rx->subdev);
> media_entity_cleanup(&csi2rx->subdev.entity);
> + pm_runtime_disable(csi2rx->dev);
> kfree(csi2rx);
> }
>
> +static int csi2rx_runtime_suspend(struct device *dev)
> +{
> + struct csi2rx_priv *csi2rx = dev_get_drvdata(dev);
> + unsigned int i;
> +
> + reset_control_assert(csi2rx->sys_rst);
> + clk_disable_unprepare(csi2rx->sys_clk);
> +
> + for (i = 0; i < csi2rx->max_streams; i++) {
> + reset_control_assert(csi2rx->pixel_rst[i]);
> + clk_disable_unprepare(csi2rx->pixel_clk[i]);
> + }
> +
> + reset_control_assert(csi2rx->p_rst);
> + clk_disable_unprepare(csi2rx->p_clk);
> +
> + return 0;
> +}
> +
> +static int csi2rx_runtime_resume(struct device *dev)
> +{
> + struct csi2rx_priv *csi2rx = dev_get_drvdata(dev);
> + unsigned int i;
> + int ret;
> +
> + ret = clk_prepare_enable(csi2rx->p_clk);
> + if (ret)
> + return ret;
> +
> + reset_control_deassert(csi2rx->p_rst);
> +
> + for (i = 0; i < csi2rx->max_streams; i++) {
> + ret = clk_prepare_enable(csi2rx->pixel_clk[i]);
> + if (ret)
> + goto err_disable_pixclk;
> +
> + reset_control_deassert(csi2rx->pixel_rst[i]);
> + }
> +
> + ret = clk_prepare_enable(csi2rx->sys_clk);
> + if (ret)
> + goto err_disable_pixclk;
> +
> + reset_control_deassert(csi2rx->sys_rst);
> +
> + return 0;
> +
> +err_disable_pixclk:
> + for (; i > 0; i--) {
> + reset_control_assert(csi2rx->pixel_rst[i - 1]);
> + clk_disable_unprepare(csi2rx->pixel_clk[i - 1]);
> + }
> +
> + reset_control_assert(csi2rx->p_rst);
> + clk_disable_unprepare(csi2rx->p_clk);
> +
> + return ret;
> +}
> +
> +static const struct dev_pm_ops csi2rx_pm_ops = {
> + RUNTIME_PM_OPS(csi2rx_runtime_suspend, csi2rx_runtime_resume, NULL)
> +};
> +
> static const struct of_device_id csi2rx_of_table[] = {
> { .compatible = "starfive,jh7110-csi2rx" },
> { .compatible = "cdns,csi2rx" },
> @@ -1141,6 +1175,7 @@ static struct platform_driver csi2rx_driver = {
> .driver = {
> .name = "cdns-csi2rx",
> .of_match_table = csi2rx_of_table,
> + .pm = &csi2rx_pm_ops,
> },
> };
> module_platform_driver(csi2rx_driver);
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