Re: [PATCH 1/2] media: hevc: Remove RPS named flags

[Benjamin Gaignard]

Le 31/08/2021 à 13:08, John Cox a écrit :
> > Marking a picture as long-term reference is valid for DPB but not for RPS.
> > Change flag name to match with it description in HEVC spec chapiter
> > "8.3.2 Decoding process for reference picture set".
> > Remove the other unused RPS flags.
> >
> > Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
> > ---
> > Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst | 6 ++----
> > drivers/staging/media/hantro/hantro_g2_hevc_dec.c         | 2 +-
> > drivers/staging/media/sunxi/cedrus/cedrus_h265.c          | 2 +-
> > include/media/hevc-ctrls.h                                | 4 +---
> > 4 files changed, 5 insertions(+), 9 deletions(-)
> >
> > diff --git a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> > index 3865acb9e0fd..eff33c511090 100644
> > --- a/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> > +++ b/Documentation/userspace-api/media/v4l/ext-ctrls-codec.rst
> > @@ -3138,10 +3138,8 @@ enum v4l2_mpeg_video_hevc_size_of_length_field -
> > 	:c:type:`timeval` in struct :c:type:`v4l2_buffer` to a __u64.
> >      * - __u8
> >        - ``rps``
> > -      - The reference set for the reference frame
> > -        (V4L2_HEVC_DPB_ENTRY_RPS_ST_CURR_BEFORE,
> > -        V4L2_HEVC_DPB_ENTRY_RPS_ST_CURR_AFTER or
> > -        V4L2_HEVC_DPB_ENTRY_RPS_LT_CURR)
> > +      - Long term flag for the reference frame
> > +        (V4L2_HEVC_DPB_ENTRY_LONG_TERM_REFERENCE)
> >      * - __u8
> >        - ``field_pic``
> >        - Whether the reference is a field picture or a frame.
> If you are going to remove all the RPS values except for Long Term
> wouldn't it be better to rename the field too, either to "flags" or a
> bool "is_long_term"?  If we have a field called RPS it really should be
> able to have a value for any of the 5 valid Reference Picture Sets that
> a DPB entry can belong to.

I will send a v2 and rename rps into flags.

> As a side note, it is important to my code that the DPB array contains
> all the DPB entries not just the ones that are in use in this frame.  I
> need them so I can track which frames have left the DPB so I can
> reuse/free the MV tables associated with them (yes I could keep one for
> every entry in the capture Q but that is generally wasteful on memory
> and the Pi is often memory constrained). So maybe update the docn on DPB
> to make this explicit please? (I suspect that current code does this
> anyway as it is generally easier to do than to not.)

That should be in another patch :-)

Benjamin

> John Cox
>
> > diff --git a/drivers/staging/media/hantro/hantro_g2_hevc_dec.c b/drivers/staging/media/hantro/hantro_g2_hevc_dec.c
> > index 9ea864ca5625..be46b3c28b17 100644
> > --- a/drivers/staging/media/hantro/hantro_g2_hevc_dec.c
> > +++ b/drivers/staging/media/hantro/hantro_g2_hevc_dec.c
> > @@ -503,7 +503,7 @@ static int set_ref(struct hantro_ctx *ctx)
> > 		compress_luma_addr = luma_addr + compress_luma_offset;
> > 		compress_chroma_addr = luma_addr + compress_chroma_offset;
> >
> > -		if (dpb[i].rps == V4L2_HEVC_DPB_ENTRY_RPS_LT_CURR)
> > +		if (dpb[i].rps == V4L2_HEVC_DPB_ENTRY_LONG_TERM_REFERENCE)
> > 			dpb_longterm_e |= BIT(V4L2_HEVC_DPB_ENTRIES_NUM_MAX - 1 - i);
> >
> > 		/*
> > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > index ef0311a16d01..6086cc35e8cc 100644
> > --- a/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_h265.c
> > @@ -169,7 +169,7 @@ static void cedrus_h265_ref_pic_list_write(struct cedrus_dev *dev,
> > 		unsigned int index = list[i];
> > 		u8 value = list[i];
> >
> > -		if (dpb[index].rps == V4L2_HEVC_DPB_ENTRY_RPS_LT_CURR)
> > +		if (dpb[index].rps == V4L2_HEVC_DPB_ENTRY_LONG_TERM_REFERENCE)
> > 			value |= VE_DEC_H265_SRAM_REF_PIC_LIST_LT_REF;
> >
> > 		/* Each SRAM word gathers up to 4 references. */
> > diff --git a/include/media/hevc-ctrls.h b/include/media/hevc-ctrls.h
> > index ef63bc205756..f587448ef495 100644
> > --- a/include/media/hevc-ctrls.h
> > +++ b/include/media/hevc-ctrls.h
> > @@ -127,9 +127,7 @@ struct v4l2_ctrl_hevc_pps {
> > 	__u64	flags;
> > };
> >
> > -#define V4L2_HEVC_DPB_ENTRY_RPS_ST_CURR_BEFORE	0x01
> > -#define V4L2_HEVC_DPB_ENTRY_RPS_ST_CURR_AFTER	0x02
> > -#define V4L2_HEVC_DPB_ENTRY_RPS_LT_CURR		0x03
> > +#define V4L2_HEVC_DPB_ENTRY_LONG_TERM_REFERENCE	0x01
> >
> > #define V4L2_HEVC_DPB_ENTRIES_NUM_MAX		16