Re: [PATCH v5 15/19] drm/msm/dpu: initialize dpu encoder and connector for writeback

[Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>]

On 4/26/2022 7:56 AM, Laurent Pinchart wrote:
> On Tue, Apr 26, 2022 at 05:11:41AM +0300, Dmitry Baryshkov wrote:
> > On 26/04/2022 03:32, Laurent Pinchart wrote:
> > > On Sun, Apr 24, 2022 at 05:32:06PM -0700, Abhinav Kumar wrote:
> > > > Initialize dpu encoder and connector for writeback if the
> > > > target supports it in the catalog.
> > > >
> > > > changes in v2:
> > > > 	- start initialing the encoder for writeback since we
> > > > 	have migrated to using drm_writeback_connector_init_with_encoder()
> > > > 	- instead of checking for WB_2 inside _dpu_kms_initialize_writeback
> > > > 	call it only when its WB_2
> > > > 	- rebase on tip of msm-next and remove usage of priv->encoders
> > > >
> > > > changes in v3:
> > > > 	- none
> > > >
> > > > changes in v4:
> > > > 	- fix copyright years order
> > > >
> > > > Signed-off-by: Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx>
> > > > Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > > > ---
> > > >    drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 27 +++++++++----
> > > >    drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c     | 61 ++++++++++++++++++++++++++++-
> > > >    2 files changed, 80 insertions(+), 8 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > > index 24870eb..2d79002 100644
> > > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > > @@ -2102,7 +2102,7 @@ static void dpu_encoder_early_unregister(struct drm_encoder *encoder)
> > > >    }
> > > >    
> > > >    static int dpu_encoder_virt_add_phys_encs(
> > > > -		u32 display_caps,
> > > > +		struct msm_display_info *disp_info,
> > > >    		struct dpu_encoder_virt *dpu_enc,
> > > >    		struct dpu_enc_phys_init_params *params)
> > > >    {
> > > > @@ -2121,7 +2121,7 @@ static int dpu_encoder_virt_add_phys_encs(
> > > >    		return -EINVAL;
> > > >    	}
> > > >    
> > > > -	if (display_caps & MSM_DISPLAY_CAP_VID_MODE) {
> > > > +	if (disp_info->capabilities & MSM_DISPLAY_CAP_VID_MODE) {
> > > >    		enc = dpu_encoder_phys_vid_init(params);
> > > >    
> > > >    		if (IS_ERR_OR_NULL(enc)) {
> > > > @@ -2134,7 +2134,7 @@ static int dpu_encoder_virt_add_phys_encs(
> > > >    		++dpu_enc->num_phys_encs;
> > > >    	}
> > > >    
> > > > -	if (display_caps & MSM_DISPLAY_CAP_CMD_MODE) {
> > > > +	if (disp_info->capabilities & MSM_DISPLAY_CAP_CMD_MODE) {
> > > >    		enc = dpu_encoder_phys_cmd_init(params);
> > > >    
> > > >    		if (IS_ERR_OR_NULL(enc)) {
> > > > @@ -2147,6 +2147,19 @@ static int dpu_encoder_virt_add_phys_encs(
> > > >    		++dpu_enc->num_phys_encs;
> > > >    	}
> > > >    
> > > > +	if (disp_info->intf_type == DRM_MODE_ENCODER_VIRTUAL) {
> > > > +		enc = dpu_encoder_phys_wb_init(params);
> > > > +
> > > > +		if (IS_ERR_OR_NULL(enc)) {
> > > > +			DPU_ERROR_ENC(dpu_enc, "failed to init wb enc: %ld\n",
> > > > +					PTR_ERR(enc));
> > > > +			return enc == NULL ? -EINVAL : PTR_ERR(enc);
> > > > +		}
> > > > +
> > > > +		dpu_enc->phys_encs[dpu_enc->num_phys_encs] = enc;
> > > > +		++dpu_enc->num_phys_encs;
> > > > +	}
> > > > +
> > > >    	if (params->split_role == ENC_ROLE_SLAVE)
> > > >    		dpu_enc->cur_slave = enc;
> > > >    	else
> > > > @@ -2248,9 +2261,8 @@ static int dpu_encoder_setup_display(struct dpu_encoder_virt *dpu_enc,
> > > >    		}
> > > >    
> > > >    		if (!ret) {
> > > > -			ret = dpu_encoder_virt_add_phys_encs(disp_info->capabilities,
> > > > -												 dpu_enc,
> > > > -												 &phys_params);
> > > > +			ret = dpu_encoder_virt_add_phys_encs(disp_info,
> > > > +					dpu_enc, &phys_params);
> > > >    			if (ret)
> > > >    				DPU_ERROR_ENC(dpu_enc, "failed to add phys encs\n");
> > > >    		}
> > > > @@ -2367,8 +2379,9 @@ struct drm_encoder *dpu_encoder_init(struct drm_device *dev,
> > > >    	if (!dpu_enc)
> > > >    		return ERR_PTR(-ENOMEM);
> > > >    
> > > > +
> > > >    	rc = drm_encoder_init(dev, &dpu_enc->base, &dpu_encoder_funcs,
> > > > -			drm_enc_mode, NULL);
> > > > +							  drm_enc_mode, NULL);
> > > >    	if (rc) {
> > > >    		devm_kfree(dev->dev, dpu_enc);
> > > >    		return ERR_PTR(rc);
> > > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > > > index c683cab..9a406e1 100644
> > > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
> > > > @@ -1,7 +1,9 @@
> > > >    // SPDX-License-Identifier: GPL-2.0-only
> > > >    /*
> > > > - * Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
> > > >     * Copyright (C) 2013 Red Hat
> > > > + * Copyright (c) 2014-2018, The Linux Foundation. All rights reserved.
> > > > + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights reserved.
> > > > + *
> > > >     * Author: Rob Clark <robdclark@xxxxxxxxx>
> > > >     */
> > > >    
> > > > @@ -15,6 +17,7 @@
> > > >    #include <drm/drm_crtc.h>
> > > >    #include <drm/drm_file.h>
> > > >    #include <drm/drm_vblank.h>
> > > > +#include <drm/drm_writeback.h>
> > > >    
> > > >    #include "msm_drv.h"
> > > >    #include "msm_mmu.h"
> > > > @@ -29,6 +32,7 @@
> > > >    #include "dpu_kms.h"
> > > >    #include "dpu_plane.h"
> > > >    #include "dpu_vbif.h"
> > > > +#include "dpu_writeback.h"
> > > >    
> > > >    #define CREATE_TRACE_POINTS
> > > >    #include "dpu_trace.h"
> > > > @@ -648,6 +652,45 @@ static int _dpu_kms_initialize_displayport(struct drm_device *dev,
> > > >    	return 0;
> > > >    }
> > > >    
> > > > +static int _dpu_kms_initialize_writeback(struct drm_device *dev,
> > > > +		struct msm_drm_private *priv, struct dpu_kms *dpu_kms,
> > > > +		const u32 *wb_formats, int n_formats)
> > > > +{
> > > > +	struct drm_encoder *encoder = NULL;
> > > > +	struct msm_display_info info;
> > > > +	int rc;
> > > > +
> > > > +	encoder = dpu_encoder_init(dev, DRM_MODE_ENCODER_VIRTUAL);
> > >
> > > I'm puzzled. I thought the whole purpose of the
> > > drm_writeback_connector_init_with_encoder() function was to share an
> > > encoder between writeback and a real display output, but the encoder you
> > > create here seems to be specific to writeback. What am I missing ?
> >
> > The encoder instance is specific to the writeback, however the encoder's
> > code is shared between the virtual and 'real' encoders. All the code for
> > encoder callbacks, resource management, irq handling is shared between
> > them. It wouldn't be practical to duplicate or rewrite the whole
> > dpu_encoder.c. During the design stage we have discussed several other
> > possibile solutions. All of them look pretty ugly.
>
> Does it mean that the output paths and the writeback paths have separate
> resources ?

They share pretty much all of the hardware resources such as clocks , 
interrupts and fetch bandwidth management.


> > > > +	if (IS_ERR(encoder)) {
> > > > +		DPU_ERROR("encoder init failed for dsi display\n");
> > > > +		return PTR_ERR(encoder);
> > > > +	}
> > > > +
> > > > +	memset(&info, 0, sizeof(info));
> > > > +
> > > > +	rc = dpu_writeback_init(dev, encoder, wb_formats,
> > > > +			n_formats);
> > > > +	if (rc) {
> > > > +		DPU_ERROR("dpu_writeback_init, rc = %d\n", rc);
> > > > +		drm_encoder_cleanup(encoder);
> > > > +		return rc;
> > > > +	}
> > > > +
> > > > +	info.num_of_h_tiles = 1;
> > > > +	/* use only WB idx 2 instance for DPU */
> > > > +	info.h_tile_instance[0] = WB_2;
> > > > +	info.intf_type = encoder->encoder_type;
> > > > +
> > > > +	rc = dpu_encoder_setup(dev, encoder, &info);
> > > > +	if (rc) {
> > > > +		DPU_ERROR("failed to setup DPU encoder %d: rc:%d\n",
> > > > +				  encoder->base.id, rc);
> > > > +		return rc;
> > > > +	}
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +
> > > >    /**
> > > >     * _dpu_kms_setup_displays - create encoders, bridges and connectors
> > > >     *                           for underlying displays
> > > > @@ -661,6 +704,7 @@ static int _dpu_kms_setup_displays(struct drm_device *dev,
> > > >    				    struct dpu_kms *dpu_kms)
> > > >    {
> > > >    	int rc = 0;
> > > > +	int i;
> > > >    
> > > >    	rc = _dpu_kms_initialize_dsi(dev, priv, dpu_kms);
> > > >    	if (rc) {
> > > > @@ -674,6 +718,21 @@ static int _dpu_kms_setup_displays(struct drm_device *dev,
> > > >    		return rc;
> > > >    	}
> > > >    
> > > > +	/* Since WB isn't a driver check the catalog before initializing */
> > > > +	if (dpu_kms->catalog->wb_count) {
> > > > +		for (i = 0; i < dpu_kms->catalog->wb_count; i++) {
> > > > +			if (dpu_kms->catalog->wb[i].id == WB_2) {
> > > > +				rc = _dpu_kms_initialize_writeback(dev, priv, dpu_kms,
> > > > +						dpu_kms->catalog->wb[i].format_list,
> > > > +						dpu_kms->catalog->wb[i].num_formats);
> > > > +				if (rc) {
> > > > +					DPU_ERROR("initialize_WB failed, rc = %d\n", rc);
> > > > +					return rc;
> > > > +				}
> > > > +			}
> > > > +		}
> > > > +	}
> > > > +
> > > >    	return rc;
> > > >    }
> > > >