Re: [PATCH v2 06/22] drm/msm/dpu: simplify peer LM handling

[Marijn Suijten <marijn.suijten@somainline.org>]

On 2023-06-13 03:09:45, Dmitry Baryshkov wrote:
> For each LM there is at max 1 peer LM which can be driven by the same
> CTL, so there no need to have a mask instead of just an ID of the peer
> LM.
> 
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

Nit: I think you can describe the the patch contents in the title:

    Replace LM peer mask with index

Instead of the vague (IMHO) "simplify handling".

> ---
>  .../gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c    |  2 +-
>  .../gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h    |  4 +--
>  drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c        | 34 +++++++------------
>  3 files changed, 15 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c
> index 0de507d4d7b7..30fb5b1f3966 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.c
> @@ -394,7 +394,7 @@ static const struct dpu_sspp_sub_blks qcm2290_dma_sblk_0 = _DMA_SBLK("8", 1);
>  	.features = _fmask, \
>  	.sblk = _sblk, \
>  	.pingpong = _pp, \
> -	.lm_pair_mask = (1 << _lmpair), \
> +	.lm_pair = _lmpair, \
>  	.dspp = _dspp \
>  	}
>  
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> index b860784ade72..b07caa4b867e 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> @@ -554,14 +554,14 @@ struct dpu_sspp_cfg {
>   * @features           bit mask identifying sub-blocks/features
>   * @sblk:              LM Sub-blocks information
>   * @pingpong:          ID of connected PingPong, PINGPONG_NONE if unsupported
> - * @lm_pair_mask:      Bitmask of LMs that can be controlled by same CTL
> + * @lm_pair:           ID of LM that can be controlled by same CTL

Of *the* LM
By *the* same CTL

But then the rest of these comments have this borked hard-to-read style
as well.

>   */
>  struct dpu_lm_cfg {
>  	DPU_HW_BLK_INFO;
>  	const struct dpu_lm_sub_blks *sblk;
>  	u32 pingpong;
>  	u32 dspp;
> -	unsigned long lm_pair_mask;
> +	unsigned long lm_pair;
>  };
>  
>  /**
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> index 471842bbb950..e333f4eeafc1 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
> @@ -253,28 +253,19 @@ static bool _dpu_rm_needs_split_display(const struct msm_display_topology *top)
>  }
>  
>  /**
> - * _dpu_rm_check_lm_peer - check if a mixer is a peer of the primary
> + * _dpu_rm_get_lm_peer - get the id of a mixer which is a peer of the primary

... mixer?

>   * @rm: dpu resource manager handle
>   * @primary_idx: index of primary mixer in rm->mixer_blks[]
> - * @peer_idx: index of other mixer in rm->mixer_blks[]
> - * Return: true if rm->mixer_blks[peer_idx] is a peer of
> - *          rm->mixer_blks[primary_idx]
>   */
> -static bool _dpu_rm_check_lm_peer(struct dpu_rm *rm, int primary_idx,
> -		int peer_idx)
> +static int _dpu_rm_get_lm_peer(struct dpu_rm *rm, int primary_idx)
>  {
>  	const struct dpu_lm_cfg *prim_lm_cfg;
> -	const struct dpu_lm_cfg *peer_cfg;
>  
>  	prim_lm_cfg = to_dpu_hw_mixer(rm->mixer_blks[primary_idx])->cap;
> -	peer_cfg = to_dpu_hw_mixer(rm->mixer_blks[peer_idx])->cap;
>  
> -	if (!test_bit(peer_cfg->id, &prim_lm_cfg->lm_pair_mask)) {
> -		DPU_DEBUG("lm %d not peer of lm %d\n", peer_cfg->id,
> -				peer_cfg->id);
> -		return false;
> -	}
> -	return true;
> +	if (prim_lm_cfg->lm_pair >= LM_0 && prim_lm_cfg->lm_pair < LM_MAX)
> +		return prim_lm_cfg->lm_pair - LM_0;
> +	return -EINVAL;
>  }
>  
>  /**
> @@ -351,7 +342,7 @@ static int _dpu_rm_reserve_lms(struct dpu_rm *rm,
>  	int lm_idx[MAX_BLOCKS];
>  	int pp_idx[MAX_BLOCKS];
>  	int dspp_idx[MAX_BLOCKS] = {0};
> -	int i, j, lm_count = 0;
> +	int i, lm_count = 0;
>  
>  	if (!reqs->topology.num_lm) {
>  		DPU_ERROR("invalid number of lm: %d\n", reqs->topology.num_lm);
> @@ -376,16 +367,15 @@ static int _dpu_rm_reserve_lms(struct dpu_rm *rm,
>  		++lm_count;
>  
>  		/* Valid primary mixer found, find matching peers */
> -		for (j = i + 1; j < ARRAY_SIZE(rm->mixer_blks) &&
> -				lm_count < reqs->topology.num_lm; j++) {
> -			if (!rm->mixer_blks[j])
> +		if (lm_count < reqs->topology.num_lm) {
> +			int j = _dpu_rm_get_lm_peer(rm, i);
> +
> +			/* ignore the peer if there is an error or if the peer was already processed */

I would not call this an "error" (though it is -EINVAL): 0 (out of range
of LM_0 <= x M LM_MAX) is a valid value meaning "LM has no peer" and
maybe another error code is more fitting?

> +			if (j < 0 || j < i)
>  				continue;
>  
> -			if (!_dpu_rm_check_lm_peer(rm, i, j)) {
> -				DPU_DEBUG("lm %d not peer of lm %d\n", LM_0 + j,
> -						LM_0 + i);
> +			if (!rm->mixer_blks[j])
>  				continue;

This seems silly now, why would an existing LM have a pair to an LM that
might not be in the catalog?  Return -EINVAL?

Nits aside, this is some tight cleanup:

Reviewed-by: Marijn Suijten <marijn.suijten@somainline.org>

- Marijn

> -			}
>  
>  			if (!_dpu_rm_check_lm_and_get_connected_blks(rm,
>  					global_state, enc_id, j,
> -- 
> 2.39.2
>