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Message-ID: <CAA8EJpqX0AWmLMrNo23cfsnU5q0ySDUkb1XTGwaxGt0eTPkLpg@mail.gmail.com>
Date: Thu, 30 Nov 2023 05:57:19 +0200
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Kuogee Hsieh <quic_khsieh@...cinc.com>
Cc: dri-devel@...ts.freedesktop.org, robdclark@...il.com,
sean@...rly.run, swboyd@...omium.org, dianders@...omium.org,
vkoul@...nel.org, daniel@...ll.ch, airlied@...il.com,
agross@...nel.org, andersson@...nel.org, quic_abhinavk@...cinc.com,
quic_jesszhan@...cinc.com, quic_sbillaka@...cinc.com,
marijn.suijten@...ainline.org, freedreno@...ts.freedesktop.org,
linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] drm/msm/dpu: improve DSC allocation
On Wed, 29 Nov 2023 at 22:31, Kuogee Hsieh <quic_khsieh@...cinc.com> wrote:
>
> A DCE (Display Compression Engine) contains two DSC hard slice encoders.
> Each DCE start with even DSC encoder index followed by an odd DSC encoder
> index. Each encoder can work independently. But Only two DSC encoders from
> same DCE can be paired to work together to support merge mode. In addition,
> the DSC with even index have to mapping to even pingpong index and DSC with
> odd index have to mapping to odd pingpong index at its data path. This patch
> improve DSC allocation mechanism with consideration of above factors.
Is this applicable to old DSC 1.1 encoders?
>
> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
> ---
> drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c | 94 +++++++++++++++++++++++++++++-----
> 1 file changed, 82 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> index f9215643..427d70d 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> @@ -466,24 +466,94 @@ static int _dpu_rm_reserve_dsc(struct dpu_rm *rm,
> struct drm_encoder *enc,
> const struct msm_display_topology *top)
> {
> - int num_dsc = top->num_dsc;
> - int i;
> + int num_dsc = 0;
> + int i, pp_idx;
> + bool pair = false;
> + int dsc_idx[DSC_MAX - DSC_0];
> + uint32_t pp_to_enc_id[PINGPONG_MAX - PINGPONG_0];
> + int pp_max = PINGPONG_MAX - PINGPONG_0;
> +
> + if (!top->num_dsc || !top->num_intf)
> + return 0;
> +
> + /*
> + * Truth:
> + * 1) every layer mixer only connects to one pingpong
> + * 2) no pingpong split -- two layer mixers shared one pingpong
> + * 3) each DSC engine contains two dsc encoders
> + * -- index(0,1), index (2,3),... etc
> + * 4) dsc pair can only happens with same DSC engine except 4 dsc
> + * merge mode application (8k) which need two DSC engines
> + * 5) odd pingpong connect to odd dsc
> + * 6) even pingpong connect even dsc
> + */
> +
> + /* num_dsc should be either 1, 2 or 4 */
> + if (top->num_dsc > top->num_intf) /* merge mode */
> + pair = true;
> +
> + /* fill working copy with pingpong list */
> + memcpy(pp_to_enc_id, global_state->pingpong_to_enc_id, sizeof(pp_to_enc_id));
> +
> + for (i = 0; i < ARRAY_SIZE(rm->dsc_blks); i++) {
&& num_dsc < top->num_dsc
> + if (!rm->dsc_blks[i]) /* end of dsc list */
> + break;
I'd say, it's `continue' instead, let's just skip the index.
>
> - /* check if DSC required are allocated or not */
> - for (i = 0; i < num_dsc; i++) {
> - if (!rm->dsc_blks[i]) {
> - DPU_ERROR("DSC %d does not exist\n", i);
> - return -EIO;
> + if (global_state->dsc_to_enc_id[i]) { /* used */
> + /* consective dsc index to be paired */
> + if (pair && num_dsc) { /* already start pairing, re start */
> + num_dsc = 0;
> + /* fill working copy with pingpong list */
> + memcpy(pp_to_enc_id, global_state->pingpong_to_enc_id,
> + sizeof(pp_to_enc_id));
> + }
> + continue;
> }
>
> - if (global_state->dsc_to_enc_id[i]) {
> - DPU_ERROR("DSC %d is already allocated\n", i);
> - return -EIO;
> + /* odd index can not become start of pairing */
> + if (pair && (i & 0x01) && !num_dsc)
> + continue;
After looking at all conditions, can we have two different helpers?
One which allocates a single DSC and another one which allocates a
pair. For the pair you can skip odd indices at all and just check if
DSC_i and DSC_i+1 are free.
> +
> + /*
> + * find the pingpong index which had been reserved
> + * previously at layer mixer allocation
> + */
> + for (pp_idx = 0; pp_idx < pp_max; pp_idx++) {
> + if (pp_to_enc_id[pp_idx] == enc->base.id)
> + break;
> }
> +
> + /*
> + * dsc even index must map to pingpong even index
> + * dsc odd index must map to pingpong odd index
> + */
> + if ((i & 0x01) != (pp_idx & 0x01))
> + continue;
> +
> + /*
> + * delete pp_idx so that it can not be found at next search
> + * in the case of pairing
> + */
> + pp_to_enc_id[pp_idx] = NULL;
> +
> + dsc_idx[num_dsc++] = i;
> + if (num_dsc >= top->num_dsc)
> + break;
> }
>
> - for (i = 0; i < num_dsc; i++)
> - global_state->dsc_to_enc_id[i] = enc->base.id;
> + if (num_dsc < top->num_dsc) {
> + DPU_ERROR("DSC allocation failed num_dsc=%d required=%d\n",
> + num_dsc, top->num_dsc );
> + return -ENAVAIL;
> + }
> +
> + /* reserve dsc */
> + for (i = 0; i < top->num_dsc; i++) {
> + int j;
> +
> + j = dsc_idx[i];
> + global_state->dsc_to_enc_id[j] = enc->base.id;
> + }
>
> return 0;
> }
> --
> 2.7.4
>
--
With best wishes
Dmitry
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