Re: [PATCH 09/16] media: cadence: csi2rx: Turn subdev power on before starting stream

Laurent Pinchart
2021-04-02T10:56:25Z

Hi Pratyush,

Thank you for the patch.

On Tue, Mar 30, 2021 at 11:03:41PM +0530, Pratyush Yadav wrote:
> The subdevice power needs to be turned on before the stream is started.
> Otherwise it might not be in the proper state to stream the data. Turn
> it off when stopping the stream.

The .s_power() operation is deprecated. Subdev drivers should control
power internally in their .s_stream() operation, and they should use
runtime PM to do so (this will allow usage of runtime PM autosuspend, to
avoid expensive power off/on cycles when stopping and restarting video
capture).

> Signed-off-by: Pratyush Yadav <p.yadav@ti.com>
> ---
> drivers/media/platform/cadence/cdns-csi2rx.c | 8 ++++++++
> 1 file changed, 8 insertions(+)
>
> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
> index 7d1ac51e0698..3385e1bc213e 100644
> --- a/drivers/media/platform/cadence/cdns-csi2rx.c
> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
> @@ -256,6 +256,10 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
>
> writel(reg, csi2rx->base + CSI2RX_STATIC_CFG_REG);
>
> + ret = v4l2_subdev_call(csi2rx->source_subdev, core, s_power, true);
> + if (ret && ret != -ENOIOCTLCMD)
> + goto err_disable_pclk;
> +
> ret = v4l2_subdev_call(csi2rx->source_subdev, video, s_stream, true);
> if (ret)
> goto err_disable_pclk;
> @@ -358,6 +362,10 @@ static void csi2rx_stop(struct csi2rx_priv *csi2rx)
> if (v4l2_subdev_call(csi2rx->source_subdev, video, s_stream, false))
> dev_warn(csi2rx->dev, "Couldn't disable our subdev\n");
>
> + ret = v4l2_subdev_call(csi2rx->source_subdev, core, s_power, false);
> + if (ret && ret != -ENOIOCTLCMD)
> + dev_warn(csi2rx->dev, "Couldn't power off subdev\n");
> +
> if (csi2rx->dphy) {
> writel(0, csi2rx->base + CSI2RX_DPHY_LANE_CTRL_REG);
>

--
Regards,

Laurent Pinchart