Use one of the struct v4l2_create_buffers reserved bytes to report the maximum possible number of buffers for the queue. V4l2 framework set V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS flags in queue capabilities so userland can know when the field is valid. Does the same change in v4l2_create_buffers32 structure.
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| @@ -1035,6 +1035,7 @@ struct v4l2_requestbuffers { · 1034 unmodified lines | ||
| 1035 | 1035 | #define V4L2_BUF_CAP_SUPPORTS_ORPHANED_BUFS (1 << 4) |
| 1036 | 1036 | #define V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF (1 << 5) |
| 1037 | 1037 | #define V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS (1 << 6) |
| 1038 | +#define V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS (1 << 7) | |
| 1038 | 1039 | |
| 1039 | 1040 | /** |
| 1040 | 1041 | * struct v4l2_plane - plane info for multi-planar buffers |
| @@ -2605,6 +2606,9 @@ struct v4l2_dbg_chip_info { · 1564 unmodified lines | ||
| 2605 | 2606 | * @flags: additional buffer management attributes (ignored unless the |
| 2606 | 2607 | * queue has V4L2_BUF_CAP_SUPPORTS_MMAP_CACHE_HINTS capability |
| 2607 | 2608 | * and configured for MMAP streaming I/O). |
| 2609 | + * @max_num_buffers: if V4L2_BUF_CAP_SUPPORTS_MAX_NUM_BUFFERS capability flag is set | |
| 2610 | + * this field indicate the maximum possible number of buffers | |
| 2611 | + * for this queue. | |
| 2608 | 2612 | * @reserved: future extensions |
| 2609 | 2613 | */ |
| 2610 | 2614 | struct v4l2_create_buffers { |
| @@ -2614,7 +2618,8 @@ struct v4l2_create_buffers { · 3 unmodified lines | ||
| 2614 | 2618 | struct v4l2_format format; |
| 2615 | 2619 | __u32 capabilities; |
| 2616 | 2620 | __u32 flags; |
| 2617 | − __u32 reserved[6]; | |
| 2621 | + __u32 max_num_buffers; | |
| 2622 | + __u32 reserved[5]; | |
| 2618 | 2623 | }; |
| 2619 | 2624 | |
| 2620 | 2625 | /* |