linux-kernel - Re: [PATCH] mipi-csis: Emit V4L2_EVENT_FRAME

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Message-ID: <99069f32-4bad-4cb9-aa03-4c06a596a248@ideasonboard.com>
Date: Thu, 14 Mar 2024 00:42:08 +0530
From: Umang Jain <umang.jain@...asonboard.com>
To: Stefan Klug <stefan.klug@...asonboard.com>,
 libcamera-devel@...ts.libcamera.org, linux-media@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc: Martin Kepplinger <martink@...teo.de>, Purism Kernel Team
 <kernel@...i.sm>, Fabio Estevam <festevam@...il.com>,
 Sascha Hauer <s.hauer@...gutronix.de>, Rui Miguel Silva <rmfrfs@...il.com>,
 Pengutronix Kernel Team <kernel@...gutronix.de>,
 Mauro Carvalho Chehab <mchehab@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
 NXP Linux Team <linux-imx@....com>
Subject: Re: [PATCH] mipi-csis: Emit V4L2_EVENT_FRAME_SYNC events

Hi Stefan,

Thank you for the patch.

On 13/03/24 9:00 pm, Stefan Klug wrote:
> The Samsung CSIS Mipi receiver provides a start-of-frame interrupt and
> a framecount register. As the CSI receiver is the hardware unit
> that lies closest to the sensor, the frame counter is the best we can
> get on these devices.
> In case of the ISI available on the i.MX8 M Plus it is also the only
> native start-of-frame signal available.
>
> This patch exposes the sof interrupt and the framecount as
> V4L2_EVENT_FRAME_SYNC event on the subdevice.
>
> It was tested on a Debix-Som-A with a 6.8-rc4 kernel.
>
> Signed-off-by: Stefan Klug <stefan.klug@...asonboard.com>
> ---
>   drivers/media/platform/nxp/imx-mipi-csis.c | 34 +++++++++++++++++++++-
>   1 file changed, 33 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/media/platform/nxp/imx-mipi-csis.c b/drivers/media/platform/nxp/imx-mipi-csis.c
> index db8ff5f5c4d3..caeb1622f741 100644
> --- a/drivers/media/platform/nxp/imx-mipi-csis.c
> +++ b/drivers/media/platform/nxp/imx-mipi-csis.c
> @@ -30,6 +30,7 @@
>   
>   #include <media/v4l2-common.h>
>   #include <media/v4l2-device.h>
> +#include <media/v4l2-event.h>
>   #include <media/v4l2-fwnode.h>
>   #include <media/v4l2-mc.h>
>   #include <media/v4l2-subdev.h>
> @@ -742,6 +743,18 @@ static void mipi_csis_stop_stream(struct mipi_csis_device *csis)
>   	mipi_csis_system_enable(csis, false);
>   }
>   
> +static void mipi_csis_queue_event_sof(struct mipi_csis_device *csis)
> +{
> +	struct v4l2_event event = {
> +		.type = V4L2_EVENT_FRAME_SYNC,
> +	};
> +
> +	u32 frame = mipi_csis_read(csis, MIPI_CSIS_FRAME_COUNTER_CH(0));

nit: variables declaration go at the start of function and then need to 
be assigned.

rest is pointed already on the thread. Otherwise LGTM,

Reviewed-by: Umang Jain <umang.jain@...asonboard.com>



> +
> +	event.u.frame_sync.frame_sequence = frame;
> +	v4l2_event_queue(csis->sd.devnode, &event);
> +}
> +
>   static irqreturn_t mipi_csis_irq_handler(int irq, void *dev_id)
>   {
>   	struct mipi_csis_device *csis = dev_id;
> @@ -765,6 +778,10 @@ static irqreturn_t mipi_csis_irq_handler(int irq, void *dev_id)
>   				event->counter++;
>   		}
>   	}
> +
> +	if (status & MIPI_CSIS_INT_SRC_FRAME_START)
> +		mipi_csis_queue_event_sof(csis);
> +
>   	spin_unlock_irqrestore(&csis->slock, flags);
>   
>   	mipi_csis_write(csis, MIPI_CSIS_INT_SRC, status);
> @@ -1154,8 +1171,23 @@ static int mipi_csis_log_status(struct v4l2_subdev *sd)
>   	return 0;
>   }
>   
> +static int mipi_csis_subscribe_event(struct v4l2_subdev *sd, struct v4l2_fh *fh,
> +			       struct v4l2_event_subscription *sub)
> +{
> +	if (sub->type != V4L2_EVENT_FRAME_SYNC)
> +		return -EINVAL;
> +
> +	/* V4L2_EVENT_FRAME_SYNC doesn't require an id, so zero should be set */
> +	if (sub->id != 0)
> +		return -EINVAL;
> +
> +	return v4l2_event_subscribe(fh, sub, 0, NULL);
> +}
> +
>   static const struct v4l2_subdev_core_ops mipi_csis_core_ops = {
>   	.log_status	= mipi_csis_log_status,
> +	.subscribe_event =  mipi_csis_subscribe_event,
> +	.unsubscribe_event = v4l2_event_subdev_unsubscribe,
>   };
>   
>   static const struct v4l2_subdev_video_ops mipi_csis_video_ops = {
> @@ -1358,7 +1390,7 @@ static int mipi_csis_subdev_init(struct mipi_csis_device *csis)
>   	snprintf(sd->name, sizeof(sd->name), "csis-%s",
>   		 dev_name(csis->dev));
>   
> -	sd->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
> +	sd->flags |= V4L2_SUBDEV_FL_HAS_DEVNODE | V4L2_SUBDEV_FL_HAS_EVENTS;
>   	sd->ctrl_handler = NULL;
>   
>   	sd->entity.function = MEDIA_ENT_F_VID_IF_BRIDGE;