[v5] media: imx-mipi-csis: Get the number of active lanes from mbus_config

[PATCH v5 4/4] media: imx-mipi-csis: Support active data lanes differing from maximum

Posted by Isaac Scott 3 months, 2 weeks ago

Call on v4l2_get_active_data_lanes() to check if the driver reports that
the number of lanes actively used by the MIPI CSI transmitter differs to
the maximum defined in device tree.

If the number of active data lanes reported by the driver is invalid, or
the operation is not supported, fall back to the number of allowed data
lanes.

Signed-off-by: Isaac Scott <isaac.scott@ideasonboard.com>
---
 drivers/media/platform/nxp/imx-mipi-csis.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/media/platform/nxp/imx-mipi-csis.c b/drivers/media/platform/nxp/imx-mipi-csis.c
index 838a1ad123b5..637ef6e614fa 100644
--- a/drivers/media/platform/nxp/imx-mipi-csis.c
+++ b/drivers/media/platform/nxp/imx-mipi-csis.c
@@ -1034,6 +1034,10 @@ static int mipi_csis_s_stream(struct v4l2_subdev *sd, int enable)
 	format = v4l2_subdev_state_get_format(state, CSIS_PAD_SINK);
 	csis_fmt = find_csis_format(format->code);
 
+	ret = v4l2_get_active_data_lanes(csis->source.pad,
+					 csis->bus.num_data_lanes);
+	csis->num_data_lanes = ret < 0 ? csis->bus.num_data_lanes : ret;
+
 	ret = mipi_csis_calculate_params(csis, csis_fmt);
 	if (ret < 0)
 		goto err_unlock;
-- 
2.43.0

Re: [PATCH v5 4/4] media: imx-mipi-csis: Support active data lanes differing from maximum

Posted by Bryan O'Donoghue 3 months, 2 weeks ago

On 22/10/2025 11:22, Isaac Scott wrote:
> Call on v4l2_get_active_data_lanes() to check if the driver reports that
> the number of lanes actively used by the MIPI CSI transmitter differs to
> the maximum defined in device tree.
> 
> If the number of active data lanes reported by the driver is invalid, or
> the operation is not supported, fall back to the number of allowed data
> lanes.
> 
> Signed-off-by: Isaac Scott <isaac.scott@ideasonboard.com>
> ---
>   drivers/media/platform/nxp/imx-mipi-csis.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/media/platform/nxp/imx-mipi-csis.c b/drivers/media/platform/nxp/imx-mipi-csis.c
> index 838a1ad123b5..637ef6e614fa 100644
> --- a/drivers/media/platform/nxp/imx-mipi-csis.c
> +++ b/drivers/media/platform/nxp/imx-mipi-csis.c
> @@ -1034,6 +1034,10 @@ static int mipi_csis_s_stream(struct v4l2_subdev *sd, int enable)
>   	format = v4l2_subdev_state_get_format(state, CSIS_PAD_SINK);
>   	csis_fmt = find_csis_format(format->code);
> 
> +	ret = v4l2_get_active_data_lanes(csis->source.pad,
> +					 csis->bus.num_data_lanes);
> +	csis->num_data_lanes = ret < 0 ? csis->bus.num_data_lanes : ret;

The function you've added can return -EINVAL;

Isn't that a fundamental error at this point ? It would make sense to 
trap -EINVAL and refuse to go further.

> +
>   	ret = mipi_csis_calculate_params(csis, csis_fmt);
>   	if (ret < 0)
>   		goto err_unlock;
> --
> 2.43.0
> 
>

Re: [PATCH v5 4/4] media: imx-mipi-csis: Support active data lanes differing from maximum

Posted by Frank Li 3 months, 2 weeks ago

On Wed, Oct 22, 2025 at 11:22:28AM +0100, Isaac Scott wrote:
> Call on v4l2_get_active_data_lanes() to check if the driver reports that
> the number of lanes actively used by the MIPI CSI transmitter differs to
> the maximum defined in device tree.
>
> If the number of active data lanes reported by the driver is invalid, or
> the operation is not supported, fall back to the number of allowed data
> lanes.
>
> Signed-off-by: Isaac Scott <isaac.scott@ideasonboard.com>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

>  drivers/media/platform/nxp/imx-mipi-csis.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/media/platform/nxp/imx-mipi-csis.c b/drivers/media/platform/nxp/imx-mipi-csis.c
> index 838a1ad123b5..637ef6e614fa 100644
> --- a/drivers/media/platform/nxp/imx-mipi-csis.c
> +++ b/drivers/media/platform/nxp/imx-mipi-csis.c
> @@ -1034,6 +1034,10 @@ static int mipi_csis_s_stream(struct v4l2_subdev *sd, int enable)
>  	format = v4l2_subdev_state_get_format(state, CSIS_PAD_SINK);
>  	csis_fmt = find_csis_format(format->code);
>
> +	ret = v4l2_get_active_data_lanes(csis->source.pad,
> +					 csis->bus.num_data_lanes);
> +	csis->num_data_lanes = ret < 0 ? csis->bus.num_data_lanes : ret;
> +
>  	ret = mipi_csis_calculate_params(csis, csis_fmt);
>  	if (ret < 0)
>  		goto err_unlock;
> --
> 2.43.0
>

Re: [PATCH v5 4/4] media: imx-mipi-csis: Support active data lanes differing from maximum

Posted by Sakari Ailus 3 months, 2 weeks ago

Hi Isaac,

On Wed, Oct 22, 2025 at 11:22:28AM +0100, Isaac Scott wrote:
> Call on v4l2_get_active_data_lanes() to check if the driver reports that
> the number of lanes actively used by the MIPI CSI transmitter differs to
> the maximum defined in device tree.
> 
> If the number of active data lanes reported by the driver is invalid, or
> the operation is not supported, fall back to the number of allowed data
> lanes.
> 
> Signed-off-by: Isaac Scott <isaac.scott@ideasonboard.com>
> ---
>  drivers/media/platform/nxp/imx-mipi-csis.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/media/platform/nxp/imx-mipi-csis.c b/drivers/media/platform/nxp/imx-mipi-csis.c
> index 838a1ad123b5..637ef6e614fa 100644
> --- a/drivers/media/platform/nxp/imx-mipi-csis.c
> +++ b/drivers/media/platform/nxp/imx-mipi-csis.c
> @@ -1034,6 +1034,10 @@ static int mipi_csis_s_stream(struct v4l2_subdev *sd, int enable)
>  	format = v4l2_subdev_state_get_format(state, CSIS_PAD_SINK);
>  	csis_fmt = find_csis_format(format->code);
>  
> +	ret = v4l2_get_active_data_lanes(csis->source.pad,
> +					 csis->bus.num_data_lanes);
> +	csis->num_data_lanes = ret < 0 ? csis->bus.num_data_lanes : ret;

I guess this works but should we return an error here instead?

Alternatively, the function could always return some number of lanes as
well (with a printed warning on error). I think I'd do the former though.

> +
>  	ret = mipi_csis_calculate_params(csis, csis_fmt);
>  	if (ret < 0)
>  		goto err_unlock;

-- 
Regards,

Sakari Ailus

Re: [PATCH v5 4/4] media: imx-mipi-csis: Support active data lanes differing from maximum

Posted by Laurent Pinchart 3 months, 2 weeks ago

On Wed, Oct 22, 2025 at 02:13:09PM +0300, Sakari Ailus wrote:
> On Wed, Oct 22, 2025 at 11:22:28AM +0100, Isaac Scott wrote:
> > Call on v4l2_get_active_data_lanes() to check if the driver reports that
> > the number of lanes actively used by the MIPI CSI transmitter differs to
> > the maximum defined in device tree.
> > 
> > If the number of active data lanes reported by the driver is invalid, or
> > the operation is not supported, fall back to the number of allowed data
> > lanes.
> > 
> > Signed-off-by: Isaac Scott <isaac.scott@ideasonboard.com>
> > ---
> >  drivers/media/platform/nxp/imx-mipi-csis.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/media/platform/nxp/imx-mipi-csis.c b/drivers/media/platform/nxp/imx-mipi-csis.c
> > index 838a1ad123b5..637ef6e614fa 100644
> > --- a/drivers/media/platform/nxp/imx-mipi-csis.c
> > +++ b/drivers/media/platform/nxp/imx-mipi-csis.c
> > @@ -1034,6 +1034,10 @@ static int mipi_csis_s_stream(struct v4l2_subdev *sd, int enable)
> >  	format = v4l2_subdev_state_get_format(state, CSIS_PAD_SINK);
> >  	csis_fmt = find_csis_format(format->code);
> >  
> > +	ret = v4l2_get_active_data_lanes(csis->source.pad,
> > +					 csis->bus.num_data_lanes);
> > +	csis->num_data_lanes = ret < 0 ? csis->bus.num_data_lanes : ret;
> 
> I guess this works but should we return an error here instead?
> 
> Alternatively, the function could always return some number of lanes as
> well (with a printed warning on error). I think I'd do the former though.

Agreed, I would return an error.

> > +
> >  	ret = mipi_csis_calculate_params(csis, csis_fmt);
> >  	if (ret < 0)
> >  		goto err_unlock;

-- 
Regards,

Laurent Pinchart