Re: [PATCH v4 18/25] drm/msm/dpu: Reserve resources for CWB

[Jessica Zhang <quic_jesszhan@quicinc.com>]

On 12/20/2024 5:07 PM, Dmitry Baryshkov wrote:
> On Fri, Dec 20, 2024 at 04:12:29PM -0800, Jessica Zhang wrote:
>>
>>
>> On 12/19/2024 9:52 PM, Dmitry Baryshkov wrote:
>>> On Mon, Dec 16, 2024 at 04:43:29PM -0800, Jessica Zhang wrote:
>>>> Add support for RM to reserve dedicated CWB PINGPONGs and CWB muxes
>>>>
>>>> For concurrent writeback, even-indexed CWB muxes must be assigned to
>>>> even-indexed LMs and odd-indexed CWB muxes for odd-indexed LMs. The same
>>>> even/odd rule applies for dedicated CWB PINGPONGs.
>>>>
>>>> Track the CWB muxes in the global state and add a CWB-specific helper to
>>>> reserve the correct CWB muxes and dedicated PINGPONGs following the
>>>> even/odd rule.
>>>>
>>>> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
>>>> ---
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 34 ++++++++++--
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h |  2 +
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h     |  1 +
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c      | 83 +++++++++++++++++++++++++++++
>>>>    4 files changed, 116 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>>> index a895d48fe81ccc71d265e089992786e8b6268b1b..a95dc1f0c6a422485c7ba98743e944e1a4f43539 100644
>>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>>>> @@ -2,7 +2,7 @@
>>>>    /*
>>>>     * Copyright (C) 2013 Red Hat
>>>>     * Copyright (c) 2014-2018, 2020-2021 The Linux Foundation. All rights reserved.
>>>> - * Copyright (c) 2022-2023 Qualcomm Innovation Center, Inc. All rights reserved.
>>>> + * Copyright (c) 2022-2024 Qualcomm Innovation Center, Inc. All rights reserved.
>>>>     *
>>>>     * Author: Rob Clark <robdclark@gmail.com>
>>>>     */
>>>> @@ -28,6 +28,7 @@
>>>>    #include "dpu_hw_dsc.h"
>>>>    #include "dpu_hw_merge3d.h"
>>>>    #include "dpu_hw_cdm.h"
>>>> +#include "dpu_hw_cwb.h"
>>>>    #include "dpu_formats.h"
>>>>    #include "dpu_encoder_phys.h"
>>>>    #include "dpu_crtc.h"
>>>> @@ -133,6 +134,9 @@ enum dpu_enc_rc_states {
>>>>     * @cur_slave:		As above but for the slave encoder.
>>>>     * @hw_pp:		Handle to the pingpong blocks used for the display. No.
>>>>     *			pingpong blocks can be different than num_phys_encs.
>>>> + * @hw_cwb:		Handle to the CWB muxes used for concurrent writeback
>>>> + *			display. Number of CWB muxes can be different than
>>>> + *			num_phys_encs.
>>>>     * @hw_dsc:		Handle to the DSC blocks used for the display.
>>>>     * @dsc_mask:		Bitmask of used DSC blocks.
>>>>     * @intfs_swapped:	Whether or not the phys_enc interfaces have been swapped
>>>> @@ -177,6 +181,7 @@ struct dpu_encoder_virt {
>>>>    	struct dpu_encoder_phys *cur_master;
>>>>    	struct dpu_encoder_phys *cur_slave;
>>>>    	struct dpu_hw_pingpong *hw_pp[MAX_CHANNELS_PER_ENC];
>>>> +	struct dpu_hw_cwb *hw_cwb[MAX_CHANNELS_PER_ENC];
>>>>    	struct dpu_hw_dsc *hw_dsc[MAX_CHANNELS_PER_ENC];
>>>>    	unsigned int dsc_mask;
>>>> @@ -1138,7 +1143,10 @@ static void dpu_encoder_virt_atomic_mode_set(struct drm_encoder *drm_enc,
>>>>    	struct dpu_hw_blk *hw_pp[MAX_CHANNELS_PER_ENC];
>>>>    	struct dpu_hw_blk *hw_ctl[MAX_CHANNELS_PER_ENC];
>>>>    	struct dpu_hw_blk *hw_dsc[MAX_CHANNELS_PER_ENC];
>>>> +	struct dpu_hw_blk *hw_cwb[MAX_CHANNELS_PER_ENC];
>>>>    	int num_pp, num_dsc, num_ctl;
>>>> +	int num_cwb = 0;
>>>> +	bool is_cwb_encoder;
>>>>    	unsigned int dsc_mask = 0;
>>>>    	int i;
>>>> @@ -1152,6 +1160,8 @@ static void dpu_encoder_virt_atomic_mode_set(struct drm_encoder *drm_enc,
>>>>    	priv = drm_enc->dev->dev_private;
>>>>    	dpu_kms = to_dpu_kms(priv->kms);
>>>> +	is_cwb_encoder = drm_crtc_in_clone_mode(crtc_state) &&
>>>> +			dpu_enc->disp_info.intf_type == INTF_WB;
>>>>    	global_state = dpu_kms_get_existing_global_state(dpu_kms);
>>>>    	if (IS_ERR_OR_NULL(global_state)) {
>>>> @@ -1162,9 +1172,25 @@ static void dpu_encoder_virt_atomic_mode_set(struct drm_encoder *drm_enc,
>>>>    	trace_dpu_enc_mode_set(DRMID(drm_enc));
>>>>    	/* Query resource that have been reserved in atomic check step. */
>>>> -	num_pp = dpu_rm_get_assigned_resources(&dpu_kms->rm, global_state,
>>>> -		drm_enc->crtc, DPU_HW_BLK_PINGPONG, hw_pp,
>>>> -		ARRAY_SIZE(hw_pp));
>>>> +	if (is_cwb_encoder) {
>>>> +		num_pp = dpu_rm_get_assigned_resources(&dpu_kms->rm, global_state,
>>>> +						       drm_enc->crtc,
>>>> +						       DPU_HW_BLK_DCWB_PINGPONG,
>>>> +						       hw_pp, ARRAY_SIZE(hw_pp));
>>>> +		num_cwb = dpu_rm_get_assigned_resources(&dpu_kms->rm, global_state,
>>>> +						       drm_enc->crtc,
>>>> +						       DPU_HW_BLK_CWB,
>>>> +						       hw_cwb, ARRAY_SIZE(hw_cwb));
>>>> +	} else {
>>>> +		num_pp = dpu_rm_get_assigned_resources(&dpu_kms->rm, global_state,
>>>> +						       drm_enc->crtc,
>>>> +						       DPU_HW_BLK_PINGPONG, hw_pp,
>>>> +						       ARRAY_SIZE(hw_pp));
>>>> +	}
>>>> +
>>>> +	for (i = 0; i < num_cwb; i++)
>>>> +		dpu_enc->hw_cwb[i] = to_dpu_hw_cwb(hw_cwb[i]);
>>>> +
>>>>    	num_ctl = dpu_rm_get_assigned_resources(&dpu_kms->rm, global_state,
>>>>    			drm_enc->crtc, DPU_HW_BLK_CTL, hw_ctl, ARRAY_SIZE(hw_ctl));
>>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
>>>> index ba7bb05efe9b8cac01a908e53121117e130f91ec..8d820cd1b5545d247515763039b341184e814e32 100644
>>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
>>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
>>>> @@ -77,12 +77,14 @@ enum dpu_hw_blk_type {
>>>>    	DPU_HW_BLK_LM,
>>>>    	DPU_HW_BLK_CTL,
>>>>    	DPU_HW_BLK_PINGPONG,
>>>> +	DPU_HW_BLK_DCWB_PINGPONG,
>>>>    	DPU_HW_BLK_INTF,
>>>>    	DPU_HW_BLK_WB,
>>>>    	DPU_HW_BLK_DSPP,
>>>>    	DPU_HW_BLK_MERGE_3D,
>>>>    	DPU_HW_BLK_DSC,
>>>>    	DPU_HW_BLK_CDM,
>>>> +	DPU_HW_BLK_CWB,
>>>>    	DPU_HW_BLK_MAX,
>>>>    };
>>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>>>> index 48d756d8f8c6e4ab94b72bac0418320f7dc8cda8..1fc8abda927fc094b369e0d1efc795b71d6a7fcb 100644
>>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.h
>>>> @@ -128,6 +128,7 @@ struct dpu_global_state {
>>>>    	uint32_t dspp_to_crtc_id[DSPP_MAX - DSPP_0];
>>>>    	uint32_t dsc_to_crtc_id[DSC_MAX - DSC_0];
>>>>    	uint32_t cdm_to_crtc_id;
>>>> +	uint32_t cwb_to_crtc_id[CWB_MAX - CWB_0];
>>>>    };
>>>>    struct dpu_global_state
>>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
>>>> index 85adaf256b2c705d2d7df378b6ffc0e578f52bc3..ead24bb0ceb5d8ec4705f0d32330294d0b45b216 100644
>>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
>>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_rm.c
>>>> @@ -234,6 +234,55 @@ static int _dpu_rm_get_lm_peer(struct dpu_rm *rm, int primary_idx)
>>>>    	return -EINVAL;
>>>>    }
>>>> +static int _dpu_rm_reserve_cwb_mux_and_pingpongs(struct dpu_rm *rm,
>>>> +						 struct dpu_global_state *global_state,
>>>> +						 uint32_t crtc_id,
>>>> +						 struct msm_display_topology *topology)
>>>> +{
>>>> +	int num_cwb_pp = topology->num_lm, cwb_pp_count = 0;
>>>> +	int cwb_pp_start_idx = PINGPONG_CWB_0 - PINGPONG_0;
>>>> +	int cwb_pp_idx[MAX_BLOCKS];
>>>> +	int cwb_mux_idx[MAX_BLOCKS];
>>>> +
>>>> +	/*
>>>> +	 * Reserve additional dedicated CWB PINGPONG blocks and muxes for each
>>>> +	 * mixer
>>>> +	 *
>>>> +	 * TODO: add support reserving resources for platforms with no
>>>> +	 *       PINGPONG_CWB
>>>
>>> What about doing it other way around: allocate CWBs first as required
>>> (even/odd, proper count, etc). Then for each of CWBs allocate a PP block
>>> (I think it's enough to simply make CWB blocks have a corresponding PP
>>> index as a property). This way the driver can handle both legacy and
>>> current platforms.
>>
>> Hi Dmitry,
>>
>> Sorry if I'm misunderstanding your suggestion, but the main change needed to
>> support platforms with no dedicated PINGPONG_CWB is where in the
>> rm->pingpong_blks list to start assigning pingpong blocks for the CWB mux.
>> I'm not sure how changing the order in which CWBs and the pingpong blocks
>> are assigned will address that.
>>
>> (FWIW, the only change necessary to add support for non-dedicated
>> PINGPONG_CWBs platforms for this function should just be changing the
>> initialization value of cwb_pp_start_idx)
> 
> If I remember correctly, we have identified several generations of DPU
> wrt. CWB handling:
> - 8.1+ (or 8.0+?), DCWB, dedicated PP blocks
> - 7.2, dedicated PP_1?
> - 5.0+, shared PP blocks
> - older DPUs, special handling of PP
> 
> If the driver allocates PP first and then first it has to allocated PP
> (in a platform-specific way) and then go from PINGPONG to CWB (in a
> platform-specific way). If CWB is allocated first, then you have only
> one platform-specific piece of code that gets PINGPONG for the CWB (and
> as this function is called after the CWB allocation, the major part of
> the CWB / PP allocation is generic).

The issue with breaking this into separate helpers/functions is that the 
CWB mux and PPB indices are dependent on each other. But I agree that we 
can reserve CWB mux and the PPBs in 2 separate loops within this helper 
to minimize the special platform-specific handling.

Also wanted to note that the comment doc on the PPB odd/even rule is 
inaccurate -- technically the odd/even rule applies specifically to the 
CWB mux as odd/even LMs are hardwired to their respective CWB muxes. 
Will correct the comment doc to be more accurate.

Thanks,

Jessica Zhang

> 
>>
>> Thanks,
>>
>> Jessica Zhang
>>
>>>
>>>> +	 */
>>>> +	for (int i = 0; i < ARRAY_SIZE(rm->mixer_blks) &&
>>>> +	     cwb_pp_count < num_cwb_pp; i++) {
>>>> +		for (int j = cwb_pp_start_idx;
>>>> +		     j < ARRAY_SIZE(rm->pingpong_blks); j++) {
>>>> +			/*
>>>> +			 * Odd LMs must be assigned to odd PINGPONGs and even
>>>> +			 * LMs with even PINGPONGs
>>>> +			 */
>>>> +			if (reserved_by_other(global_state->pingpong_to_crtc_id, j, crtc_id) ||
>>>> +			    i % 2 != j % 2)
>>>> +				continue;
>>>> +
>>>> +			cwb_pp_idx[cwb_pp_count] = j;
>>>> +			cwb_mux_idx[cwb_pp_count] = j - cwb_pp_start_idx;
>>>> +			cwb_pp_count++;
>>>> +			break;
>>>> +		}
>>>> +	}
>>>> +
>>>> +	if (cwb_pp_count != num_cwb_pp) {
>>>> +		DPU_ERROR("Unable to reserve all CWB PINGPONGs\n");
>>>> +		return -ENAVAIL;
>>>> +	}
>>>> +
>>>> +	for (int i = 0; i < cwb_pp_count; i++) {
>>>> +		global_state->pingpong_to_crtc_id[cwb_pp_idx[i]] = crtc_id;
>>>> +		global_state->cwb_to_crtc_id[cwb_mux_idx[i]] = crtc_id;
>>>> +	}
>>>> +
>>>> +	return 0;
>>>> +}
>>>> +
>>>>    /**
>>>>     * _dpu_rm_check_lm_and_get_connected_blks - check if proposed layer mixer meets
>>>>     *	proposed use case requirements, incl. hardwired dependent blocks like
>>>> @@ -614,6 +663,12 @@ static int _dpu_rm_make_reservation(
>>>>    		return ret;
>>>>    	}
>>>> +	if (topology->cwb_enabled) {
>>>> +		ret = _dpu_rm_reserve_cwb_mux_and_pingpongs(rm, global_state,
>>>> +							    crtc_id, topology);
>>>> +		if (ret)
>>>> +			return ret;
>>>> +	}
>>>>    	ret = _dpu_rm_reserve_ctls(rm, global_state, crtc_id,
>>>>    			topology);
>>>> @@ -671,6 +726,8 @@ void dpu_rm_release(struct dpu_global_state *global_state,
>>>>    	_dpu_rm_clear_mapping(global_state->dspp_to_crtc_id,
>>>>    			ARRAY_SIZE(global_state->dspp_to_crtc_id), crtc_id);
>>>>    	_dpu_rm_clear_mapping(&global_state->cdm_to_crtc_id, 1, crtc_id);
>>>> +	_dpu_rm_clear_mapping(global_state->cwb_to_crtc_id,
>>>> +			ARRAY_SIZE(global_state->cwb_to_crtc_id), crtc_id);
>>>>    }
>>>>    /**
>>>> @@ -733,6 +790,7 @@ int dpu_rm_get_assigned_resources(struct dpu_rm *rm,
>>>>    	switch (type) {
>>>>    	case DPU_HW_BLK_PINGPONG:
>>>> +	case DPU_HW_BLK_DCWB_PINGPONG:
>>>>    		hw_blks = rm->pingpong_blks;
>>>>    		hw_to_crtc_id = global_state->pingpong_to_crtc_id;
>>>>    		max_blks = ARRAY_SIZE(rm->pingpong_blks);
>>>> @@ -762,6 +820,11 @@ int dpu_rm_get_assigned_resources(struct dpu_rm *rm,
>>>>    		hw_to_crtc_id = &global_state->cdm_to_crtc_id;
>>>>    		max_blks = 1;
>>>>    		break;
>>>> +	case DPU_HW_BLK_CWB:
>>>> +		hw_blks = rm->cwb_blks;
>>>> +		hw_to_crtc_id = global_state->cwb_to_crtc_id;
>>>> +		max_blks = ARRAY_SIZE(rm->cwb_blks);
>>>> +		break;
>>>>    	default:
>>>>    		DPU_ERROR("blk type %d not managed by rm\n", type);
>>>>    		return 0;
>>>> @@ -772,6 +835,20 @@ int dpu_rm_get_assigned_resources(struct dpu_rm *rm,
>>>>    		if (hw_to_crtc_id[i] != crtc_id)
>>>>    			continue;
>>>> +		if (type == DPU_HW_BLK_PINGPONG) {
>>>> +			struct dpu_hw_pingpong *pp = to_dpu_hw_pingpong(hw_blks[i]);
>>>> +
>>>> +			if (pp->idx >= PINGPONG_CWB_0)
>>>> +				continue;
>>>> +		}
>>>> +
>>>> +		if (type == DPU_HW_BLK_DCWB_PINGPONG) {
>>>> +			struct dpu_hw_pingpong *pp = to_dpu_hw_pingpong(hw_blks[i]);
>>>> +
>>>> +			if (pp->idx < PINGPONG_CWB_0)
>>>> +				continue;
>>>> +		}
>>>> +
>>>>    		if (num_blks == blks_size) {
>>>>    			DPU_ERROR("More than %d resources assigned to crtc %d\n",
>>>>    				  blks_size, crtc_id);
>>>> @@ -847,4 +924,10 @@ void dpu_rm_print_state(struct drm_printer *p,
>>>>    	dpu_rm_print_state_helper(p, rm->cdm_blk,
>>>>    				  global_state->cdm_to_crtc_id);
>>>>    	drm_puts(p, "\n");
>>>> +
>>>> +	drm_puts(p, "\tcwb=");
>>>> +	for (i = 0; i < ARRAY_SIZE(global_state->cwb_to_crtc_id); i++)
>>>> +		dpu_rm_print_state_helper(p, rm->cwb_blks[i],
>>>> +					  global_state->cwb_to_crtc_id[i]);
>>>> +	drm_puts(p, "\n");
>>>>    }
>>>>
>>>> -- 
>>>> 2.34.1
>>>>
>>>
>>> -- 
>>> With best wishes
>>> Dmitry
>>
> 
> -- 
> With best wishes
> Dmitry