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

[Jessica Zhang <quic_jesszhan@quicinc.com>]

On 12/28/2024 8:47 PM, Dmitry Baryshkov wrote:
> On Thu, Dec 26, 2024 at 02:49:28PM -0800, Jessica Zhang wrote:
>>
>>
>> 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.
> 
> Doesn't it just PPB depend on CWB?

Sorry, poor wording on my part. Was referring specifically to this part 
of the logic within the code chunk:

```
cwb_pp_idx[cwb_pp_count] = j;
cwb_mux_idx[cwb_pp_count] = j - cwb_pp_start_idx;
```

The point I wanted to make was that I think we can keep the CWB-specific 
reservation of the the PPBs and muxes in this function, but I agree with 
your suggestion to reserve the CWBs first and the PPBs second (just in 
separate loops rather than separate functions).


> 
> 
>>
>> 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.
> 
> Yes, please fix that.
> 
>>
>> Thanks,
>>
>> Jessica Zhang
>>
> 
> -- 
> With best wishes
> Dmitry