* [PATCH 1/1] media: v4l2-subdev: Introduce v4l2_subdev_get_frame_desc()
@ 2026-03-29 19:56 Sakari Ailus
2026-03-30 13:58 ` Lad, Prabhakar
0 siblings, 1 reply; 2+ messages in thread
From: Sakari Ailus @ 2026-03-29 19:56 UTC (permalink / raw)
To: linux-media
Cc: Prabhakar, Mauro Carvalho Chehab, Hans Verkuil, Hans de Goede,
Laurent Pinchart, Vladimir Zapolskiy, Mehdi Djait, Xiaolei Wang,
Benjamin Mugnier, Sylvain Petinot, Jacopo Mondi,
Hardevsinh Palaniya, linux-kernel, linux-renesas-soc, Biju Das,
Fabrizio Castro, Lad Prabhakar, Laurent Pinchart
Introduce v4l2_subdev_get_frame_desc() in order to facilitate implementing
drivers that need frame descriptors. If the remote sub-device does not
support frame descriptors, v4l2_subdev_get_frame_desc() creates one (with
a single entry) opportunistically, thus avoiding the need to add frame
descriptor support to sensor drivers the device for which only generates a
single stream, or managing the situation on the caller side.
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
---
drivers/media/v4l2-core/v4l2-subdev.c | 96 +++++++++++++++++++++++++++
include/media/v4l2-subdev.h | 20 ++++++
2 files changed, 116 insertions(+)
diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 04a5cb2ad3e3..6032b7c4b949 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -20,6 +20,7 @@
#include <linux/version.h>
#include <linux/videodev2.h>
+#include <media/mipi-csi2.h>
#include <media/v4l2-ctrls.h>
#include <media/v4l2-device.h>
#include <media/v4l2-event.h>
@@ -2790,3 +2791,98 @@ void v4l2_subdev_put_privacy_led(struct v4l2_subdev *sd)
#endif
}
EXPORT_SYMBOL_GPL(v4l2_subdev_put_privacy_led);
+
+static int get_mipi_dt_for_mbus(u32 code)
+{
+ switch (code) {
+ case MEDIA_BUS_FMT_BGR888_1X24:
+ return MIPI_CSI2_DT_RGB888;
+ case MEDIA_BUS_FMT_Y8_1X8:
+ case MEDIA_BUS_FMT_SBGGR8_1X8:
+ case MEDIA_BUS_FMT_SGBRG8_1X8:
+ case MEDIA_BUS_FMT_SGRBG8_1X8:
+ case MEDIA_BUS_FMT_SRGGB8_1X8:
+ return MIPI_CSI2_DT_RAW8;
+ case MEDIA_BUS_FMT_Y10_1X10:
+ case MEDIA_BUS_FMT_SBGGR10_1X10:
+ case MEDIA_BUS_FMT_SGBRG10_1X10:
+ case MEDIA_BUS_FMT_SGRBG10_1X10:
+ case MEDIA_BUS_FMT_SRGGB10_1X10:
+ return MIPI_CSI2_DT_RAW10;
+ case MEDIA_BUS_FMT_Y12_1X12:
+ case MEDIA_BUS_FMT_SBGGR12_1X12:
+ case MEDIA_BUS_FMT_SGBRG12_1X12:
+ case MEDIA_BUS_FMT_SGRBG12_1X12:
+ case MEDIA_BUS_FMT_SRGGB12_1X12:
+ return MIPI_CSI2_DT_RAW12;
+ case MEDIA_BUS_FMT_Y14_1X14:
+ case MEDIA_BUS_FMT_SBGGR14_1X14:
+ case MEDIA_BUS_FMT_SGBRG14_1X14:
+ case MEDIA_BUS_FMT_SGRBG14_1X14:
+ case MEDIA_BUS_FMT_SRGGB14_1X14:
+ return MIPI_CSI2_DT_RAW14;
+ case MEDIA_BUS_FMT_Y16_1X16:
+ case MEDIA_BUS_FMT_SBGGR16_1X16:
+ case MEDIA_BUS_FMT_SGBRG16_1X16:
+ case MEDIA_BUS_FMT_SGRBG16_1X16:
+ case MEDIA_BUS_FMT_SRGGB16_1X16:
+ return MIPI_CSI2_DT_RAW16;
+ case MEDIA_BUS_FMT_SBGGR20_1X20:
+ case MEDIA_BUS_FMT_SGBRG20_1X20:
+ case MEDIA_BUS_FMT_SGRBG20_1X20:
+ case MEDIA_BUS_FMT_SRGGB20_1X20:
+ return MIPI_CSI2_DT_RAW20;
+ default:
+ return -EINVAL;
+ }
+}
+
+int v4l2_subdev_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
+ struct v4l2_mbus_frame_desc *desc)
+{
+ if (v4l2_subdev_has_op(sd, pad, get_frame_desc)) {
+ unsigned int type = desc->type;
+ int ret;
+
+ ret = v4l2_subdev_call(sd, pad, get_frame_desc, pad, desc);
+
+ if (desc->type != type)
+ return -EINVAL;
+
+ return ret;
+ }
+
+ if (desc->type != V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL &&
+ desc->type != V4L2_MBUS_FRAME_DESC_TYPE_CSI2)
+ return -EINVAL;
+
+ struct v4l2_subdev_state *state =
+ v4l2_subdev_lock_and_get_active_state(sd);
+ if (!state)
+ return -EINVAL;
+
+ struct v4l2_mbus_framefmt *fmt =
+ v4l2_subdev_state_get_format(state, pad, 0);
+ if (!fmt)
+ return -EINVAL;
+
+ struct v4l2_mbus_frame_desc_entry entry = {
+ .pixelcode = fmt->code,
+ };
+
+ if (desc->type == V4L2_MBUS_FRAME_DESC_TYPE_CSI2) {
+ int dt;
+
+ dt = get_mipi_dt_for_mbus(fmt->code);
+ if (dt < 0)
+ return dt;
+
+ entry.bus.csi2.dt = dt;
+ }
+
+ desc->entry[0] = entry;
+ desc->num_entries = 1;
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_subdev_get_frame_desc);
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 97b487b1507a..9b0e091c30c1 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -2100,4 +2100,24 @@ void v4l2_subdev_notify_event(struct v4l2_subdev *sd,
*/
bool v4l2_subdev_is_streaming(struct v4l2_subdev *sd);
+/**
+ * v4l2_subdev_get_frame_desc() - Get a pad's frame descriptor
+ * @sd: The sub-device
+ * @pad: The number of the pad in @sd from which to obtain the frame descriptor
+ * @desc: A pointer to a frame descriptor, with its type field set
+ *
+ * Obtain a frame descriptor from a sub-device. If the sub-device supports the
+ * get_frame_desc pad operation, its result is returned, just like calling it
+ * directly using v4l2_subdev_call(). If the sub-device driver does not support
+ * it, then one containing a single entry is created using the information from
+ * the sub-device active state, which this function locks for the duration of
+ * the call to obtain it.
+ *
+ * The caller is required to set @desc->type to the expected bus type.
+ *
+ * Return: %0 on success or negative error code on failure.
+ */
+int v4l2_subdev_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
+ struct v4l2_mbus_frame_desc *desc);
+
#endif /* _V4L2_SUBDEV_H */
--
2.47.3
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH 1/1] media: v4l2-subdev: Introduce v4l2_subdev_get_frame_desc()
2026-03-29 19:56 [PATCH 1/1] media: v4l2-subdev: Introduce v4l2_subdev_get_frame_desc() Sakari Ailus
@ 2026-03-30 13:58 ` Lad, Prabhakar
0 siblings, 0 replies; 2+ messages in thread
From: Lad, Prabhakar @ 2026-03-30 13:58 UTC (permalink / raw)
To: Sakari Ailus
Cc: linux-media, Mauro Carvalho Chehab, Hans Verkuil, Hans de Goede,
Laurent Pinchart, Vladimir Zapolskiy, Mehdi Djait, Xiaolei Wang,
Benjamin Mugnier, Sylvain Petinot, Jacopo Mondi,
Hardevsinh Palaniya, linux-kernel, linux-renesas-soc, Biju Das,
Fabrizio Castro, Lad Prabhakar, Laurent Pinchart
Hi Sakari,
Thank you for the patch.
On Sun, Mar 29, 2026 at 8:56 PM Sakari Ailus
<sakari.ailus@linux.intel.com> wrote:
>
> Introduce v4l2_subdev_get_frame_desc() in order to facilitate implementing
> drivers that need frame descriptors. If the remote sub-device does not
> support frame descriptors, v4l2_subdev_get_frame_desc() creates one (with
> a single entry) opportunistically, thus avoiding the need to add frame
> descriptor support to sensor drivers the device for which only generates a
> single stream, or managing the situation on the caller side.
>
> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
> drivers/media/v4l2-core/v4l2-subdev.c | 96 +++++++++++++++++++++++++++
> include/media/v4l2-subdev.h | 20 ++++++
> 2 files changed, 116 insertions(+)
>
> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
> index 04a5cb2ad3e3..6032b7c4b949 100644
> --- a/drivers/media/v4l2-core/v4l2-subdev.c
> +++ b/drivers/media/v4l2-core/v4l2-subdev.c
> @@ -20,6 +20,7 @@
> #include <linux/version.h>
> #include <linux/videodev2.h>
>
> +#include <media/mipi-csi2.h>
> #include <media/v4l2-ctrls.h>
> #include <media/v4l2-device.h>
> #include <media/v4l2-event.h>
> @@ -2790,3 +2791,98 @@ void v4l2_subdev_put_privacy_led(struct v4l2_subdev *sd)
> #endif
> }
> EXPORT_SYMBOL_GPL(v4l2_subdev_put_privacy_led);
> +
> +static int get_mipi_dt_for_mbus(u32 code)
> +{
> + switch (code) {
> + case MEDIA_BUS_FMT_BGR888_1X24:
> + return MIPI_CSI2_DT_RGB888;
> + case MEDIA_BUS_FMT_Y8_1X8:
> + case MEDIA_BUS_FMT_SBGGR8_1X8:
> + case MEDIA_BUS_FMT_SGBRG8_1X8:
> + case MEDIA_BUS_FMT_SGRBG8_1X8:
> + case MEDIA_BUS_FMT_SRGGB8_1X8:
> + return MIPI_CSI2_DT_RAW8;
> + case MEDIA_BUS_FMT_Y10_1X10:
> + case MEDIA_BUS_FMT_SBGGR10_1X10:
> + case MEDIA_BUS_FMT_SGBRG10_1X10:
> + case MEDIA_BUS_FMT_SGRBG10_1X10:
> + case MEDIA_BUS_FMT_SRGGB10_1X10:
> + return MIPI_CSI2_DT_RAW10;
> + case MEDIA_BUS_FMT_Y12_1X12:
> + case MEDIA_BUS_FMT_SBGGR12_1X12:
> + case MEDIA_BUS_FMT_SGBRG12_1X12:
> + case MEDIA_BUS_FMT_SGRBG12_1X12:
> + case MEDIA_BUS_FMT_SRGGB12_1X12:
> + return MIPI_CSI2_DT_RAW12;
> + case MEDIA_BUS_FMT_Y14_1X14:
> + case MEDIA_BUS_FMT_SBGGR14_1X14:
> + case MEDIA_BUS_FMT_SGBRG14_1X14:
> + case MEDIA_BUS_FMT_SGRBG14_1X14:
> + case MEDIA_BUS_FMT_SRGGB14_1X14:
> + return MIPI_CSI2_DT_RAW14;
> + case MEDIA_BUS_FMT_Y16_1X16:
> + case MEDIA_BUS_FMT_SBGGR16_1X16:
> + case MEDIA_BUS_FMT_SGBRG16_1X16:
> + case MEDIA_BUS_FMT_SGRBG16_1X16:
> + case MEDIA_BUS_FMT_SRGGB16_1X16:
> + return MIPI_CSI2_DT_RAW16;
> + case MEDIA_BUS_FMT_SBGGR20_1X20:
> + case MEDIA_BUS_FMT_SGBRG20_1X20:
> + case MEDIA_BUS_FMT_SGRBG20_1X20:
> + case MEDIA_BUS_FMT_SRGGB20_1X20:
> + return MIPI_CSI2_DT_RAW20;
Other bus formats are missing.
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +int v4l2_subdev_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
> + struct v4l2_mbus_frame_desc *desc)
> +{
> + if (v4l2_subdev_has_op(sd, pad, get_frame_desc)) {
> + unsigned int type = desc->type;
> + int ret;
> +
> + ret = v4l2_subdev_call(sd, pad, get_frame_desc, pad, desc);
> +
> + if (desc->type != type)
> + return -EINVAL;
> +
> + return ret;
> + }
> +
> + if (desc->type != V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL &&
> + desc->type != V4L2_MBUS_FRAME_DESC_TYPE_CSI2)
> + return -EINVAL;
Maybe we can move this check to the beginning?
> +
> + struct v4l2_subdev_state *state =
Should we define this and fmt at the top of the function?
> + v4l2_subdev_lock_and_get_active_state(sd);
> + if (!state)
> + return -EINVAL;
> +
> + struct v4l2_mbus_framefmt *fmt =
> + v4l2_subdev_state_get_format(state, pad, 0);
Missing v4l2_subdev_unlock_state().
> + if (!fmt)
> + return -EINVAL;
> +
> + struct v4l2_mbus_frame_desc_entry entry = {
> + .pixelcode = fmt->code,
> + };
> +
> + if (desc->type == V4L2_MBUS_FRAME_DESC_TYPE_CSI2) {
> + int dt;
> +
> + dt = get_mipi_dt_for_mbus(fmt->code);
> + if (dt < 0)
> + return dt;
> +
> + entry.bus.csi2.dt = dt;
> + }
> +
> + desc->entry[0] = entry;
> + desc->num_entries = 1;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(v4l2_subdev_get_frame_desc);
> diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
> index 97b487b1507a..9b0e091c30c1 100644
> --- a/include/media/v4l2-subdev.h
> +++ b/include/media/v4l2-subdev.h
> @@ -2100,4 +2100,24 @@ void v4l2_subdev_notify_event(struct v4l2_subdev *sd,
> */
> bool v4l2_subdev_is_streaming(struct v4l2_subdev *sd);
>
> +/**
> + * v4l2_subdev_get_frame_desc() - Get a pad's frame descriptor
> + * @sd: The sub-device
> + * @pad: The number of the pad in @sd from which to obtain the frame descriptor
> + * @desc: A pointer to a frame descriptor, with its type field set
> + *
> + * Obtain a frame descriptor from a sub-device. If the sub-device supports the
> + * get_frame_desc pad operation, its result is returned, just like calling it
> + * directly using v4l2_subdev_call(). If the sub-device driver does not support
> + * it, then one containing a single entry is created using the information from
> + * the sub-device active state, which this function locks for the duration of
> + * the call to obtain it.
> + *
> + * The caller is required to set @desc->type to the expected bus type.
> + *
> + * Return: %0 on success or negative error code on failure.
stray "%" char.
Rest LGTM. I tested it by adding the missing bits on my side; all seems OK.
Cheers,
Prabhakar
> + */
> +int v4l2_subdev_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
> + struct v4l2_mbus_frame_desc *desc);
> +
> #endif /* _V4L2_SUBDEV_H */
> --
> 2.47.3
>
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2026-03-29 19:56 [PATCH 1/1] media: v4l2-subdev: Introduce v4l2_subdev_get_frame_desc() Sakari Ailus
2026-03-30 13:58 ` Lad, Prabhakar
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