linux-kernel - Re: [PATCH v2 27/66] media: sun6i-csi: Add media ops with link notify callback

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Message-ID: <YgqGGJJ0oVQgRoNy@paasikivi.fi.intel.com>
Date:   Mon, 14 Feb 2022 18:40:56 +0200
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>
Cc:     linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-sunxi@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-phy@...ts.infradead.org,
        linux-clk@...r.kernel.org, linux-staging@...ts.linux.dev,
        Yong Deng <yong.deng@...ewell.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Maxime Ripard <mripard@...nel.org>,
        Hans Verkuil <hans.verkuil@...co.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Helen Koike <helen.koike@...labora.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH v2 27/66] media: sun6i-csi: Add media ops with link
 notify callback

Hi Paul,

Thanks for the update.

On Sat, Feb 05, 2022 at 07:53:50PM +0100, Paul Kocialkowski wrote:
> In order to keep the power use count fields balanced when link changes
> happen between v4l2_pipeline_pm_get/set calls (in open/close),
> the link_notify media operation callback needs to be registered.
> 
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
> ---
>  drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> index 6f04f86504bf..c8fe31cc38b5 100644
> --- a/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> +++ b/drivers/media/platform/sunxi/sun6i-csi/sun6i_csi.c
> @@ -23,6 +23,7 @@
>  #include <linux/sched.h>
>  #include <linux/sizes.h>
>  #include <linux/slab.h>
> +#include <media/v4l2-mc.h>
>  
>  #include "sun6i_csi.h"
>  #include "sun6i_csi_reg.h"
> @@ -574,6 +575,12 @@ void sun6i_csi_set_stream(struct sun6i_csi_device *csi_dev, bool enable)
>  			   CSI_CAP_CH0_VCAP_ON);
>  }
>  
> +/* Media */
> +
> +static const struct media_device_ops sun6i_csi_media_ops = {
> +	.link_notify = v4l2_pipeline_link_notify,

Do you really need this?

Drivers should instead rely on runtime PM nowadays.

<URL:https://hverkuil.home.xs4all.nl/spec/driver-api/camera-sensor.html#power-management>

> +};
> +
>  /* V4L2 */
>  
>  static int sun6i_csi_link_entity(struct sun6i_csi_device *csi_dev,
> @@ -683,6 +690,7 @@ static int sun6i_csi_v4l2_setup(struct sun6i_csi_device *csi_dev)
>  	snprintf(media_dev->bus_info, sizeof(media_dev->bus_info),
>  		 "platform:%s", dev_name(dev));
>  	media_dev->hw_revision = 0;
> +	media_dev->ops = &sun6i_csi_media_ops;
>  	media_dev->dev = dev;
>  
>  	media_device_init(media_dev);

-- 
Kind regards,

Sakari Ailus