Re: [PATCH v3 17/29] media: bcm2835-unicam: Use v4l2_subdev_get_frame_desc()

[Sakari Ailus <sakari.ailus@linux.intel.com>]

Hi Frank,

On Mon, Aug 24, 2026 at 05:07:46PM -0400, Frank Li wrote:
> On Mon, Aug 24, 2026 at 03:14:39PM +0300, Sakari Ailus wrote:
> > Call v4l2_subdev_get_frame_desc() to obtain the frame descriptor. This is
> > preferred over calling the get_frame_desc() pad operation directly.
> >
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> >  .../media/platform/broadcom/bcm2835-unicam.c  | 22 +++++++++----------
> >  1 file changed, 10 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/media/platform/broadcom/bcm2835-unicam.c b/drivers/media/platform/broadcom/bcm2835-unicam.c
> > index 14bb916dd7b1..2322d3df3915 100644
> > --- a/drivers/media/platform/broadcom/bcm2835-unicam.c
> > +++ b/drivers/media/platform/broadcom/bcm2835-unicam.c
> > @@ -27,6 +27,7 @@
> >   * output interface and V4L2 subdevice driver.
> >   */
> >
> > +#include <linux/cleanup.h>
> >  #include <linux/clk.h>
> >  #include <linux/delay.h>
> >  #include <linux/device.h>
> > @@ -888,7 +889,6 @@ static int unicam_get_image_vc_dt(struct unicam_device *unicam,
> >  				  struct v4l2_subdev_state *state,
> >  				  u8 *vc, u8 *dt)
> >  {
> > -	struct v4l2_mbus_frame_desc fd;
> >  	u32 stream;
> >  	int ret;
> >
> > @@ -898,17 +898,15 @@ static int unicam_get_image_vc_dt(struct unicam_device *unicam,
> >  	if (ret)
> >  		return ret;
> >
> > -	ret = v4l2_subdev_call(unicam->sensor.subdev, pad, get_frame_desc,
> > -			       unicam->sensor.pad->index, &fd);
> > -	if (ret)
> > -		return ret;
> > -
> > -	/* Only CSI-2 supports DTs. */
> > -	if (fd.type != V4L2_MBUS_FRAME_DESC_TYPE_CSI2)
> > -		return -EINVAL;
> > +	struct v4l2_mbus_frame_desc *fd __free(v4l2_subdev_free_frame_desc) =
> > +		v4l2_subdev_get_frame_desc(unicam->sensor.subdev,
> > +					   unicam->sensor.pad->index,
> > +					   V4L2_MBUS_FRAME_DESC_TYPE_CSI2);
> > +	if (IS_ERR(fd))
> > +		return PTR_ERR(fd);
> >
> > -	for (unsigned int i = 0; i < fd.num_entries; ++i) {
> > -		const struct v4l2_mbus_frame_desc_entry *fde = &fd.entry[i];
> > +	for (unsigned int i = 0; i < fd->num_entries; ++i) {
> > +		const struct v4l2_mbus_frame_desc_entry *fde = &fd->entry[i];
> >
> >  		if (fde->stream == stream) {
> >  			*vc = fde->bus.csi2.vc;
> > @@ -927,7 +925,7 @@ static void unicam_start_rx(struct unicam_device *unicam,
> >  	const struct unicam_format_info *fmtinfo;
> >  	const struct v4l2_mbus_framefmt *fmt;
> >  	unsigned int line_int_freq;
> > -	u8 vc, dt;
> > +	u8 vc = 0, dt = 0;
> 
> not sure why need here,
> 
> if unicam_get_image_vc_dt() return failure, vc will be set to 0
> if unicam_get_image_vc_dt() return success, vc will be expected value.

You're right -- this chunk can be dropped.

-- 
Sakari Ailus