On 6/9/19 4:38 PM, Maxime Jourdan wrote:
> Hello,
>
> This RFC proposes a new format flag - V4L2_FMT_FLAG_DYN_RESOLUTION - used
> to tag coded formats for which the device supports dynamic resolution
> switching, via V4L2_EVENT_SOURCE_CHANGE.
> This includes the initial "source change" where the device is able to
> tell userspace about the coded resolution and the DPB size (which
> sometimes translates to V4L2_CID_MIN_BUFFERS_FOR_CAPTURE).
Shouldn't the initial source change still be there? The amlogic decoder
is capable of determining the resolution of the stream, right? It just
can't handle mid-stream changes.
Regards,
Hans
> This flag is mainly aimed at stateful decoder drivers.
>
> This RFC is motivated by my development on the amlogic video decoder
> driver, which does not support dynamic resolution switching for older
> coded formats (MPEG 1/2, MPEG 4 part II, H263). It does however support
> it for the newer formats (H264, HEVC, VP9).
>
> The specification regarding stateful video decoders should be amended
> to include that, in the absence of this flag for a certain format,
> userspace is expected to extract the coded resolution and allocate
> a sufficient amount of capture buffers on its own.
> I understand that this point may be tricky, since older kernels with
> close-to-spec drivers would not have this flag available, yet would
> fully support dynamic resolution switching.
> However, with the spec not merged in yet, I wanted to have your opinion
> on this late addition.
>
> The RFC patches also adds support for this flag for the 4 following
> stateful decoder drivers:
> - venus
> - s5p-mfc
> - mtk-vcodec
> - vicodec
>
> Maxime Jourdan (5):
> media: videodev2: add V4L2_FMT_FLAG_DYN_RESOLUTION
> media: venus: vdec: flag OUTPUT formats with
> V4L2_FMT_FLAG_DYN_RESOLUTION
> media: s5p_mfc_dec: flag OUTPUT formats with
> V4L2_FMT_FLAG_DYN_RESOLUTION
> media: mtk-vcodec: flag OUTPUT formats with
> V4L2_FMT_FLAG_DYN_RESOLUTION
> media: vicodec: flag vdec/stateful OUTPUT formats with
> V4L2_FMT_FLAG_DYN_RESOLUTION
>
> Documentation/media/uapi/v4l/vidioc-enum-fmt.rst | 7 +++++++
> drivers/media/platform/mtk-vcodec/mtk_vcodec_dec.c | 4 ++++
> drivers/media/platform/mtk-vcodec/mtk_vcodec_drv.h | 1 +
> drivers/media/platform/qcom/venus/core.h | 1 +
> drivers/media/platform/qcom/venus/vdec.c | 11 +++++++++++
> drivers/media/platform/s5p-mfc/s5p_mfc_common.h | 1 +
> drivers/media/platform/s5p-mfc/s5p_mfc_dec.c | 13 +++++++++++++
> drivers/media/platform/vicodec/vicodec-core.c | 2 ++
> include/uapi/linux/videodev2.h | 5 +++--
> 9 files changed, 43 insertions(+), 2 deletions(-)
>
