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SubjectRe: [linux-sunxi] [PATCH v2 2/2] media: cedrus: Add H264 decoding support
Date
Dne torek, 27. november 2018 ob 16:50:28 CET je Maxime Ripard napisal(a):
> Hi Jernej,
>
> Thanks for your review!
>
> On Sat, Nov 24, 2018 at 09:43:43PM +0100, Jernej Škrabec wrote:
> > > +enum cedrus_h264_sram_off {
> > > + CEDRUS_SRAM_H264_PRED_WEIGHT_TABLE = 0x000,
> > > + CEDRUS_SRAM_H264_FRAMEBUFFER_LIST = 0x100,
> > > + CEDRUS_SRAM_H264_REF_LIST_0 = 0x190,
> > > + CEDRUS_SRAM_H264_REF_LIST_1 = 0x199,
> > > + CEDRUS_SRAM_H264_SCALING_LIST_8x8 = 0x200,
> > > + CEDRUS_SRAM_H264_SCALING_LIST_4x4 = 0x218,
> >
> > I triple checked above address and it should be 0x220. For easier
> > implementation later, you might want to add second scaling list address
> > for
> > 8x8 at 0x210. Then you can do something like:
> >
> > cedrus_h264_write_sram(dev, CEDRUS_SRAM_H264_SCALING_LIST_8x8_0,
> >
> > scaling->scaling_list_8x8[0],
> > sizeof(scaling->scaling_list_8x8[0]));
> >
> > cedrus_h264_write_sram(dev, CEDRUS_SRAM_H264_SCALING_LIST_8x8_1,
> >
> > scaling->scaling_list_8x8[3],
> > sizeof(scaling->scaling_list_8x8[0]));
> >
> > cedrus_h264_write_sram(dev, CEDRUS_SRAM_H264_SCALING_LIST_4x4,
> >
> > scaling->scaling_list_4x4,
> > sizeof(scaling->scaling_list_4x4));
> >
> > I know that it's not implemented here, just FYI.
>
> Ack. I guess I can just leave it out entirely for now, since it's not
> implemented.
>
> > > +static void cedrus_fill_ref_pic(struct cedrus_ctx *ctx,
> > > + struct cedrus_buffer *buf,
> > > + unsigned int top_field_order_cnt,
> > > + unsigned int bottom_field_order_cnt,
> > > + struct cedrus_h264_sram_ref_pic *pic)
> > > +{
> > > + struct vb2_buffer *vbuf = &buf->m2m_buf.vb.vb2_buf;
> > > + unsigned int position = buf->codec.h264.position;
> > > +
> > > + pic->top_field_order_cnt = top_field_order_cnt;
> > > + pic->bottom_field_order_cnt = bottom_field_order_cnt;
> > > + pic->frame_info = buf->codec.h264.pic_type << 8;
> > > +
> > > + pic->luma_ptr = cedrus_buf_addr(vbuf, &ctx->dst_fmt, 0) - PHYS_OFFSET;
> > > + pic->chroma_ptr = cedrus_buf_addr(vbuf, &ctx->dst_fmt, 1) -
> > > PHYS_OFFSET;
> >
> > I think subtracting PHYS_OFFSET breaks driver on H3 boards with 2 GiB of
> > RAM. Isn't that unnecessary anyway due to
> >
> > dev->dev->dma_pfn_offset = PHYS_PFN_OFFSET;
> >
> > in cedrus_hw.c?
> >
> > This comment is meant for all PHYS_OFFSET subtracting in this patch.
>
> PHYS_OFFSET was needed on some older SoCs, and the dma_pfn_offset
> trick wasn't working, I hacked it and forgot about it. I'll try to
> figure it out for the next version.
>
> > > +static void _cedrus_write_ref_list(struct cedrus_ctx *ctx,
> > > + struct cedrus_run *run,
> > > + const u8 *ref_list, u8 num_ref,
> > > + enum cedrus_h264_sram_off sram)
> > > +{
> > > + const struct v4l2_ctrl_h264_decode_param *decode =
> > > run->h264.decode_param; + struct vb2_queue *cap_q =
> > > &ctx->fh.m2m_ctx->cap_q_ctx.q;
> > > + struct cedrus_dev *dev = ctx->dev;
> > > + u32 sram_array[CEDRUS_MAX_REF_IDX / sizeof(u32)];
> > > + unsigned int size, i;
> > > +
> > > + memset(sram_array, 0, sizeof(sram_array));
> > > +
> > > + for (i = 0; i < num_ref; i += 4) {
> > > + unsigned int j;
> > > +
> > > + for (j = 0; j < 4; j++) {
> >
> > I don't think you have to complicate with two loops here.
> > cedrus_h264_write_sram() takes void* and it aligns to 4 anyway. So as long
> > input buffer is multiple of 4 (u8[CEDRUS_MAX_REF_IDX] qualifies for that),
> > you can use single for loop with "u8 sram_array[CEDRUS_MAX_REF_IDX]".
> > This should make code much more readable.
>
> This wasn't really about the alignment, but in order to get the
> offsets in the u32 and the array more easily.
>
> Breaking out the loop will make that computation less easy on the eye,
> so I guess it's very subjective.
>

For some strange reason, code below fixes decoding issue from one of my test
samples. This is what I actually meant with 1 loop approach:

static void _cedrus_write_ref_list(struct cedrus_ctx *ctx,
struct cedrus_run *run,
const u8 *ref_list, u8 num_ref,
enum cedrus_h264_sram_off sram)
{
const struct v4l2_ctrl_h264_decode_param *decode = run->h264.decode_param;
struct vb2_queue *cap_q = &ctx->fh.m2m_ctx->cap_q_ctx.q;
struct cedrus_dev *dev = ctx->dev;
u8 sram_array[CEDRUS_MAX_REF_IDX];
unsigned int i;

memset(sram_array, 0, sizeof(sram_array));
num_ref = min(num_ref, (u8)CEDRUS_MAX_REF_IDX);

for (i = 0; i < num_ref; i++) {
const struct v4l2_h264_dpb_entry *dpb;
const struct cedrus_buffer *cedrus_buf;
const struct vb2_v4l2_buffer *ref_buf;
unsigned int position;
int buf_idx;
u8 dpb_idx;

dpb_idx = ref_list[i];
dpb = &decode->dpb[dpb_idx];

if (!(dpb->flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
continue;

buf_idx = vb2_find_tag(cap_q, dpb->tag, 0);
if (buf_idx < 0)
continue;

ref_buf = to_vb2_v4l2_buffer(ctx->dst_bufs[buf_idx]);
cedrus_buf = vb2_v4l2_to_cedrus_buffer(ref_buf);
position = cedrus_buf->codec.h264.position;

sram_array[i] |= position << 1;
if (ref_buf->field == V4L2_FIELD_BOTTOM)
sram_array[i] |= BIT(0);
}

cedrus_h264_write_sram(dev, sram, &sram_array, num_ref);
}

IMO this code is easier to read.

> > > + const struct v4l2_h264_dpb_entry *dpb;
> > > + const struct cedrus_buffer *cedrus_buf;
> > > + const struct vb2_v4l2_buffer *ref_buf;
> > > + unsigned int position;
> > > + int buf_idx;
> > > + u8 ref_idx = i + j;
> > > + u8 dpb_idx;
> > > +
> > > + if (ref_idx >= num_ref)
> > > + break;
> > > +
> > > + dpb_idx = ref_list[ref_idx];
> > > + dpb = &decode->dpb[dpb_idx];
> > > +
> > > + if (!(dpb->flags & V4L2_H264_DPB_ENTRY_FLAG_ACTIVE))
> > > + continue;
> > > +
> > > + buf_idx = vb2_find_tag(cap_q, dpb->tag, 0);
> > > + if (buf_idx < 0)
> > > + continue;
> > > +
> > > + ref_buf = to_vb2_v4l2_buffer(ctx->dst_bufs[buf_idx]);
> > > + cedrus_buf = vb2_v4l2_to_cedrus_buffer(ref_buf);
> > > + position = cedrus_buf->codec.h264.position;
> > > +
> > > + sram_array[i] |= position << (j * 8 + 1);
> > > + if (ref_buf->field == V4L2_FIELD_BOTTOM)
> >
> > You newer set above flag to buffer so this will be always false.
>
> As far as I know, the field is supposed to be set by the userspace.

How? I thought that only flags at queueing buffers can be set and there is no
bottom/top flag.

>
> > > + // sequence parameters
> > > + reg = BIT(19);
> >
> > This one can be inferred from sps->chroma_format_idc.
>
> I'll look into this
>

I'm using this:
reg |= (sps->chroma_format_idc & 0x7) << 19;

Although I can't tell if I tested anything else than 1 there (same as it was
before).

> > > + reg |= (sps->pic_width_in_mbs_minus1 & 0xff) << 8;
> > > + reg |= sps->pic_height_in_map_units_minus1 & 0xff;
> > > + if (sps->flags & V4L2_H264_SPS_FLAG_FRAME_MBS_ONLY)
> > > + reg |= BIT(18);
> > > + if (sps->flags & V4L2_H264_SPS_FLAG_MB_ADAPTIVE_FRAME_FIELD)
> > > + reg |= BIT(17);
> > > + if (sps->flags & V4L2_H264_SPS_FLAG_DIRECT_8X8_INFERENCE)
> > > + reg |= BIT(16);
> > > + cedrus_write(dev, VE_H264_FRAME_SIZE, reg);
> > > +
> > > + // slice parameters
> > > + reg = 0;
> > > + /*
> > > + * FIXME: This bit marks all the frames as references. This
> > > + * should probably be set based on nal_ref_idc, but the libva
> > > + * doesn't pass that information along, so this is not always
> > > + * available. We should find something else, maybe change the
> > > + * kernel UAPI somehow?
> > > + */
> > > + reg |= BIT(12);
> >
> > I really think you should use nal_ref_idc here as it is in specification.
> > You can still fake the data from libva backend. I don't think that any
> > driver needs this for anything else than check if it is 0 or not.
>
> Yeah, Tomasz suggested the same thing as a reply to the cover letter,
> I'll change that in the next version.
>
> > > + reg |= (slice->slice_type & 0xf) << 8;
> > > + reg |= slice->cabac_init_idc & 0x3;
> > > + reg |= BIT(5);
> > > + if (slice->flags & V4L2_H264_SLICE_FLAG_FIELD_PIC)
> > > + reg |= BIT(4);
> > > + if (slice->flags & V4L2_H264_SLICE_FLAG_BOTTOM_FIELD)
> > > + reg |= BIT(3);
> > > + if (slice->flags & V4L2_H264_SLICE_FLAG_DIRECT_SPATIAL_MV_PRED)
> > > + reg |= BIT(2);
> > > + cedrus_write(dev, VE_H264_SLICE_HDR, reg);
> > > +
> > > + reg = 0;
> >
> > You might want to set bit 12 here, which enables active reference picture
> > override. However, I'm not completely sure about that.
>
> Did you find some videos that were broken because of this?

No, not really. That's why I don't really know if it is needed or not.

Best regards,
Jernej



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