Re: [PATCH v8 07/18] media: cadence: csi2rx: Move to .enable/disable_streams API

[Rishikesh Donadkar <r-donadkar@ti.com>]

On 20/11/25 18:30, Tomi Valkeinen wrote:
> Hi,


Hi Tomi

>
> On 12/11/2025 13:54, Rishikesh Donadkar wrote:
>> The enable_streams() API in v4l2 supports passing a bitmask to enable
>> each pad/stream combination individually on any media subdev. Use this
>> API instead of  s_stream() API.
>>
>> Implement the enable_stream and disable_stream hooks in place of the
>> stream-unaware s_stream hook.
>>
>> Remove the lock that was used to serialize stream starts/stops which
>> is not required anymore since the v4l2-core serializes the
>> enable/disable_streams() calls for the subdev.
>>
>> Signed-off-by: Rishikesh Donadkar <r-donadkar@ti.com>
>> ---
>>   drivers/media/platform/cadence/cdns-csi2rx.c | 108 +++++++++----------
>>   1 file changed, 54 insertions(+), 54 deletions(-)
>>
>> diff --git a/drivers/media/platform/cadence/cdns-csi2rx.c b/drivers/media/platform/cadence/cdns-csi2rx.c
>> index 8c19f125da3e5..34da81893308b 100644
>> --- a/drivers/media/platform/cadence/cdns-csi2rx.c
>> +++ b/drivers/media/platform/cadence/cdns-csi2rx.c
>> @@ -125,12 +125,6 @@ struct csi2rx_priv {
>>   	unsigned int			count;
>>   	int				error_irq;
>>   
>> -	/*
>> -	 * Used to prevent race conditions between multiple,
>> -	 * concurrent calls to start and stop.
>> -	 */
>> -	struct mutex			lock;
>> -
>>   	void __iomem			*base;
>>   	struct clk			*sys_clk;
>>   	struct clk			*p_clk;
>> @@ -268,20 +262,21 @@ static int csi2rx_configure_ext_dphy(struct csi2rx_priv *csi2rx)
>>   		&csi2rx->source_subdev->entity.pads[csi2rx->source_pad];
>>   	union phy_configure_opts opts = { };
>>   	struct phy_configure_opts_mipi_dphy *cfg = &opts.mipi_dphy;
>> -	struct v4l2_subdev_format sd_fmt = {
>> -		.which	= V4L2_SUBDEV_FORMAT_ACTIVE,
>> -		.pad	= CSI2RX_PAD_SINK,
>> -	};
>> +	struct v4l2_subdev_state *state;
>> +	struct v4l2_mbus_framefmt *framefmt;
>>   	const struct csi2rx_fmt *fmt;
>>   	s64 link_freq;
>>   	int ret;
>>   
>> -	ret = v4l2_subdev_call_state_active(&csi2rx->subdev, pad, get_fmt,
>> -					    &sd_fmt);
>> -	if (ret < 0)
>> -		return ret;
>> +	state = v4l2_subdev_get_locked_active_state(&csi2rx->subdev);
>>   
>> -	fmt = csi2rx_get_fmt_by_code(sd_fmt.format.code);
>> +	framefmt = v4l2_subdev_state_get_format(state, CSI2RX_PAD_SINK, 0);
>> +	if (!framefmt) {
>> +		dev_err(csi2rx->dev, "Did not find active sink format\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	fmt = csi2rx_get_fmt_by_code(framefmt->code);
>>   
>>   	link_freq = v4l2_get_link_freq(src_pad,
>>   				       fmt->bpp, 2 * csi2rx->num_lanes);
>> @@ -401,16 +396,10 @@ static int csi2rx_start(struct csi2rx_priv *csi2rx)
>>   
>>   	reset_control_deassert(csi2rx->sys_rst);
>>   
>> -	ret = v4l2_subdev_call(csi2rx->source_subdev, video, s_stream, true);
>> -	if (ret)
>> -		goto err_disable_sysclk;
>> -
>>   	clk_disable_unprepare(csi2rx->p_clk);
>>   
>>   	return 0;
>>   
>> -err_disable_sysclk:
>> -	clk_disable_unprepare(csi2rx->sys_clk);
>>   err_disable_pixclk:
>>   	for (; i > 0; i--) {
>>   		reset_control_assert(csi2rx->pixel_rst[i - 1]);
>> @@ -459,9 +448,6 @@ static void csi2rx_stop(struct csi2rx_priv *csi2rx)
>>   	reset_control_assert(csi2rx->p_rst);
>>   	clk_disable_unprepare(csi2rx->p_clk);
>>   
>> -	if (v4l2_subdev_call(csi2rx->source_subdev, video, s_stream, false))
>> -		dev_warn(csi2rx->dev, "Couldn't disable our subdev\n");
>> -
>>   	if (csi2rx->dphy) {
>>   		writel(0, csi2rx->base + CSI2RX_DPHY_LANE_CTRL_REG);
>>   
>> @@ -485,38 +471,56 @@ static int csi2rx_log_status(struct v4l2_subdev *sd)
>>   	return 0;
>>   }
>>   
>> -static int csi2rx_s_stream(struct v4l2_subdev *subdev, int enable)
>> +static int csi2rx_enable_streams(struct v4l2_subdev *subdev,
>> +				 struct v4l2_subdev_state *state, u32 pad,
>> +				 u64 streams_mask)
>>   {
>>   	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
>> -	int ret = 0;
>> -
>> -	mutex_lock(&csi2rx->lock);
>> -
>> -	if (enable) {
>> -		/*
>> -		 * If we're not the first users, there's no need to
>> -		 * enable the whole controller.
>> -		 */
>> -		if (!csi2rx->count) {
>> -			ret = csi2rx_start(csi2rx);
>> -			if (ret)
>> -				goto out;
>> -		}
>> +	int ret;
>>   
>> -		csi2rx->count++;
>> -	} else {
>> -		csi2rx->count--;
>> +	/*
>> +	 * If we're not the first users, there's no need to
>> +	 * enable the whole controller.
>> +	 */
>> +	if (!csi2rx->count) {
>> +		ret = csi2rx_start(csi2rx);
>> +		if (ret)
>> +			return ret;
>> +	}
>>   
>> -		/*
>> -		 * Let the last user turn off the lights.
>> -		 */
>> +	/* Start streaming on the source */
>> +	ret = v4l2_subdev_enable_streams(csi2rx->source_subdev, csi2rx->source_pad,
>> +					 BIT(0));
> The stream mask is u64, so better use BIT_U64. It doesn't matter here,
> but before you know it, you have switched BIT(0) to BIT(foo->bar), and
> someone sets bar to 34 and it's broken...
>
> Yes, I see this being changed later, to variable set with BIT_ULL()
> (that could be changed to BIT_U64). Nevertheless, better use the correct
> macro.


Sure, I will change it in the next revision.

>
> But a bigger issue is if this and patches 6 and 8 are correct or could
> be improved.
>
> I think in this one you remove s_stream from cdns-csi2. But the j7
> csi2rx is still calling s_stream, so it would fail with this patch. In
> patch 8 you switch j7 csi2rx from s_stream to enable_streams. But in
> patch 6 you added mutex, locking and s_stream to j7 csi2rx, and in patch
> 8 you remove that.
>
> Maybe the end result is fine, but it all does feel messy. I think the
> patches we should have are:
>
> - Use v4l2_subdev_enable_streams() in j7-csi2rx instead of calling
> s_stream. v4l2_subdev_enable_streams() will work with either .s_stream
> and .enable_stream in cdns-csi2rx
>
> - Patch 7 (with BIT_64()) to convert cdns-csi2rx
>
> - Patches 6 and 8 combined. You're essentially adding a new subdev, just
> do it right from the start with .enable_streams, state, etc., instead of
> mutex and s_stream which are removed two patches later.


Right, I will merge changes from 08/18 into 06/18.


Thanks,

Rishikesh

>
>   Tomi
>
>> +	if (ret) {
>> +		dev_err(csi2rx->dev,
>> +			"Failed to start streams %d on subdev\n", 0);
>>   		if (!csi2rx->count)
>>   			csi2rx_stop(csi2rx);
>> +		return ret;
>>   	}
>>   
>> -out:
>> -	mutex_unlock(&csi2rx->lock);
>> -	return ret;
>> +	csi2rx->count++;
>> +	return 0;
>> +}
>> +
>> +static int csi2rx_disable_streams(struct v4l2_subdev *subdev,
>> +				  struct v4l2_subdev_state *state, u32 pad,
>> +				  u64 streams_mask)
>> +{
>> +	struct csi2rx_priv *csi2rx = v4l2_subdev_to_csi2rx(subdev);
>> +
>> +	if (v4l2_subdev_disable_streams(csi2rx->source_subdev,
>> +					csi2rx->source_pad, BIT(0))) {
>> +		dev_err(csi2rx->dev, "Couldn't disable our subdev\n");
>> +	}
>> +
>> +	csi2rx->count--;
>> +
>> +	/* Let the last user turn off the lights. */
>> +	if (!csi2rx->count)
>> +		csi2rx_stop(csi2rx);
>> +
>> +	return 0;
>>   }
>>   
>>   static int csi2rx_enum_mbus_code(struct v4l2_subdev *subdev,
>> @@ -611,10 +615,8 @@ static const struct v4l2_subdev_pad_ops csi2rx_pad_ops = {
>>   	.enum_mbus_code	= csi2rx_enum_mbus_code,
>>   	.get_fmt	= v4l2_subdev_get_fmt,
>>   	.set_fmt	= csi2rx_set_fmt,
>> -};
>> -
>> -static const struct v4l2_subdev_video_ops csi2rx_video_ops = {
>> -	.s_stream	= csi2rx_s_stream,
>> +	.enable_streams         = csi2rx_enable_streams,
>> +	.disable_streams        = csi2rx_disable_streams,
>>   };
>>   
>>   static const struct v4l2_subdev_core_ops csi2rx_core_ops = {
>> @@ -623,7 +625,6 @@ static const struct v4l2_subdev_core_ops csi2rx_core_ops = {
>>   
>>   static const struct v4l2_subdev_ops csi2rx_subdev_ops = {
>>   	.core		= &csi2rx_core_ops,
>> -	.video		= &csi2rx_video_ops,
>>   	.pad		= &csi2rx_pad_ops,
>>   };
>>   
>> @@ -829,7 +830,6 @@ static int csi2rx_probe(struct platform_device *pdev)
>>   		return -ENOMEM;
>>   	platform_set_drvdata(pdev, csi2rx);
>>   	csi2rx->dev = &pdev->dev;
>> -	mutex_init(&csi2rx->lock);
>>   
>>   	ret = csi2rx_get_resources(csi2rx, pdev);
>>   	if (ret)