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Subject: Re: [RFC PATCH 04/13] drm/msm/disp/dpu1: Add support for DSC
To:     Vinod Koul <vkoul@kernel.org>, Rob Clark <robdclark@gmail.com>
Cc:     linux-arm-msm@vger.kernel.org,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Jonathan Marek <jonathan@marek.ca>,
        Abhinav Kumar <abhinavk@codeaurora.org>,
        linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
        freedreno@lists.freedesktop.org
References: <20210521124946.3617862-1-vkoul@kernel.org>
 <20210521124946.3617862-7-vkoul@kernel.org>
From:   Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Message-ID: <c9e16e8c-9f07-11bf-77f6-1569fbc99ec4@linaro.org>
Date:   Fri, 28 May 2021 13:31:17 +0300
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On 21/05/2021 15:49, Vinod Koul wrote:
> Display Stream Compression (DSC) is one of the hw blocks in dpu, so add
> support by adding hw blocks for DSC
> 
> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> ---
>   drivers/gpu/drm/msm/Makefile                  |   1 +
>   .../gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h    |  26 +++
>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c    | 221 ++++++++++++++++++
>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.h    |  79 +++++++
>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h   |  13 ++
>   5 files changed, 340 insertions(+)
>   create mode 100644 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
>   create mode 100644 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.h
> 
> diff --git a/drivers/gpu/drm/msm/Makefile b/drivers/gpu/drm/msm/Makefile
> index 610d630326bb..fd8fc57f1f58 100644
> --- a/drivers/gpu/drm/msm/Makefile
> +++ b/drivers/gpu/drm/msm/Makefile
> @@ -61,6 +61,7 @@ msm-y := \
>   	disp/dpu1/dpu_hw_blk.o \
>   	disp/dpu1/dpu_hw_catalog.o \
>   	disp/dpu1/dpu_hw_ctl.o \
> +	disp/dpu1/dpu_hw_dsc.o \
>   	disp/dpu1/dpu_hw_interrupts.o \
>   	disp/dpu1/dpu_hw_intf.o \
>   	disp/dpu1/dpu_hw_lm.o \
> 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 4dfd8a20ad5c..a699633f7013 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_catalog.h
> @@ -165,6 +165,7 @@ enum {
>    * @DPU_PINGPONG_TE2        Additional tear check block for split pipes
>    * @DPU_PINGPONG_SPLIT      PP block supports split fifo
>    * @DPU_PINGPONG_SLAVE      PP block is a suitable slave for split fifo
> + * @DPU_PINGPONG_DSC        Display stream compression blocks
>    * @DPU_PINGPONG_DITHER,    Dither blocks
>    * @DPU_PINGPONG_MAX
>    */
> @@ -173,10 +174,21 @@ enum {
>   	DPU_PINGPONG_TE2,
>   	DPU_PINGPONG_SPLIT,
>   	DPU_PINGPONG_SLAVE,
> +	DPU_PINGPONG_DSC,
>   	DPU_PINGPONG_DITHER,
>   	DPU_PINGPONG_MAX
>   };
>   
> +/**
> + * DSC sub-blocks
> + * @DPU_DSC		DSC sub block
> + * @DPU_DSC_MAX
> + */
> +enum {
> +	DPU_DSC = 0x1,
> +	DPU_DSC_MAX
> +};

I don't think we need this. DSC is always a DSC. You can safely pass (0) 
as a features mask.

Once we'd have to add 1.2 block revision support, we might have to add 
it here.

> +
>   /**
>    * CTL sub-blocks
>    * @DPU_CTL_SPLIT_DISPLAY       CTL supports video mode split display
> @@ -413,6 +425,7 @@ struct dpu_dspp_sub_blks {
>   struct dpu_pingpong_sub_blks {
>   	struct dpu_pp_blk te;
>   	struct dpu_pp_blk te2;
> +	struct dpu_pp_blk dsc;

Is this used?


>   	struct dpu_pp_blk dither;
>   };
>   
> @@ -547,6 +560,16 @@ struct dpu_merge_3d_cfg  {
>   	const struct dpu_merge_3d_sub_blks *sblk;
>   };
>   
> +/**
> + * struct dpu_dsc_cfg - information of DSC blocks
> + * @id                 enum identifying this block
> + * @base               register offset of this block
> + * @features           bit mask identifying sub-blocks/features
> + */
> +struct dpu_dsc_cfg {
> +	DPU_HW_BLK_INFO;
> +};
> +
>   /**
>    * struct dpu_intf_cfg - information of timing engine blocks
>    * @id                 enum identifying this block
> @@ -748,6 +771,9 @@ struct dpu_mdss_cfg {
>   	u32 merge_3d_count;
>   	const struct dpu_merge_3d_cfg *merge_3d;
>   
> +	u32 dsc_count;
> +	struct dpu_dsc_cfg *dsc;
> +
>   	u32 intf_count;
>   	const struct dpu_intf_cfg *intf;
>   
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
> new file mode 100644
> index 000000000000..8b8d0553709d
> --- /dev/null
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.c
> @@ -0,0 +1,221 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2020, Linaro Limited
> + */
> +
> +#include "dpu_kms.h"
> +#include "dpu_hw_catalog.h"
> +#include "dpu_hwio.h"
> +#include "dpu_hw_mdss.h"
> +#include "dpu_hw_dsc.h"
> +
> +#define DSC_COMMON_MODE	                0x000
> +#define DSC_ENC                         0X004
> +#define DSC_PICTURE                     0x008
> +#define DSC_SLICE                       0x00C
> +#define DSC_CHUNK_SIZE                  0x010
> +#define DSC_DELAY                       0x014
> +#define DSC_SCALE_INITIAL               0x018
> +#define DSC_SCALE_DEC_INTERVAL          0x01C
> +#define DSC_SCALE_INC_INTERVAL          0x020
> +#define DSC_FIRST_LINE_BPG_OFFSET       0x024
> +#define DSC_BPG_OFFSET                  0x028
> +#define DSC_DSC_OFFSET                  0x02C
> +#define DSC_FLATNESS                    0x030
> +#define DSC_RC_MODEL_SIZE               0x034
> +#define DSC_RC                          0x038
> +#define DSC_RC_BUF_THRESH               0x03C
> +#define DSC_RANGE_MIN_QP                0x074
> +#define DSC_RANGE_MAX_QP                0x0B0
> +#define DSC_RANGE_BPG_OFFSET            0x0EC
> +
> +static void dpu_hw_dsc_disable(struct dpu_hw_dsc *dsc)
> +{
> +	struct dpu_hw_blk_reg_map *c = &dsc->hw;
> +
> +	DPU_REG_WRITE(c, DSC_COMMON_MODE, 0);
> +}
> +
> +static void dpu_hw_dsc_config(struct dpu_hw_dsc *hw_dsc,
> +			      struct msm_display_dsc_config *dsc,
> +			      u32 mode, bool ich_reset_override)
> +{
> +	struct dpu_hw_blk_reg_map *c = &hw_dsc->hw;
> +	u32 data;
> +	u32 initial_lines = dsc->initial_lines;
> +	bool is_cmd_mode = !(mode & BIT(2));
> +
> +	DPU_REG_WRITE(c, DSC_COMMON_MODE, mode);
> +
> +	data = 0;
> +	if (ich_reset_override)
> +		data = 3 << 28;

Do we need this? It seems this is only necessary for the half panel 
partial updates, which is not enabled for now. Do you know if this is 
really handy at this point or if it's an odd case? We might drop the 
ich_reset logic alltogether and add it later if/when the need arises.

> +
> +	if (is_cmd_mode)
> +		initial_lines += 1;
> +
> +	data |= (initial_lines << 20);
> +	data |= ((dsc->slice_last_group_size) << 18);
> +	/* bpp is 6.4 format, 4 LSBs bits are for fractional part */
> +	data |= dsc->drm.bits_per_pixel << 12;
> +	data |= (dsc->drm.block_pred_enable << 7);
> +	data |= (dsc->drm.line_buf_depth << 3);
> +	data |= (dsc->drm.simple_422 << 2);
> +	data |= (dsc->drm.convert_rgb << 1);
> +	if (dsc->drm.bits_per_component  == 10)
> +		data |= BIT(0);
> +
> +	DPU_REG_WRITE(c, DSC_ENC, data);
> +
> +	data = dsc->drm.pic_width << 16;
> +	data |= dsc->drm.pic_height;
> +	DPU_REG_WRITE(c, DSC_PICTURE, data);
> +
> +	data = dsc->drm.slice_width << 16;
> +	data |= dsc->drm.slice_height;
> +	DPU_REG_WRITE(c, DSC_SLICE, data);
> +
> +	data = DIV_ROUND_UP(dsc->drm.slice_width * dsc->drm.bits_per_pixel, 8) << 16;
> +
> +	DPU_REG_WRITE(c, DSC_CHUNK_SIZE, data);
> +
> +	data = dsc->drm.initial_dec_delay << 16;
> +	data |= dsc->drm.initial_xmit_delay;
> +	DPU_REG_WRITE(c, DSC_DELAY, data);
> +
> +	data = dsc->drm.initial_scale_value;
> +	DPU_REG_WRITE(c, DSC_SCALE_INITIAL, data);
> +
> +	data = dsc->drm.scale_decrement_interval;
> +	DPU_REG_WRITE(c, DSC_SCALE_DEC_INTERVAL, data);
> +
> +	data = 0x00000184; /* only this value works */
> +	DPU_REG_WRITE(c, DSC_SCALE_INC_INTERVAL, data);
> +
> +	data = dsc->drm.first_line_bpg_offset;
> +	DPU_REG_WRITE(c, DSC_FIRST_LINE_BPG_OFFSET, data);
> +
> +	data = dsc->drm.nfl_bpg_offset << 16;
> +	data |= dsc->drm.slice_bpg_offset;
> +	DPU_REG_WRITE(c, DSC_BPG_OFFSET, data);
> +
> +	data = dsc->drm.initial_offset << 16;
> +	data |= dsc->drm.final_offset;
> +	DPU_REG_WRITE(c, DSC_DSC_OFFSET, data);
> +
> +	data = dsc->det_thresh_flatness << 10;
> +	data |= dsc->drm.flatness_max_qp << 5;
> +	data |= dsc->drm.flatness_min_qp;
> +	DPU_REG_WRITE(c, DSC_FLATNESS, data);
> +
> +	data = dsc->drm.rc_model_size;
> +	DPU_REG_WRITE(c, DSC_RC_MODEL_SIZE, data);
> +
> +	data = dsc->drm.rc_tgt_offset_low << 18;
> +	data |= dsc->drm.rc_tgt_offset_high << 14;
> +	data |= dsc->drm.rc_quant_incr_limit1 << 9;
> +	data |= dsc->drm.rc_quant_incr_limit0 << 4;
> +	data |= dsc->drm.rc_edge_factor;
> +	DPU_REG_WRITE(c, DSC_RC, data);
> +}
> +
> +static void dpu_hw_dsc_config_thresh(struct dpu_hw_dsc *hw_dsc,
> +				     struct msm_display_dsc_config *dsc)
> +{
> +	struct drm_dsc_rc_range_parameters *rc = dsc->drm.rc_range_params;
> +	struct dpu_hw_blk_reg_map *c = &hw_dsc->hw;
> +	u32 off = 0x0;
> +	u16 *lp;
> +	int i;
> +
> +	lp = dsc->drm.rc_buf_thresh;
> +	off = DSC_RC_BUF_THRESH;
> +	for (i = 0; i < DSC_NUM_BUF_RANGES - 1 ; i++) {
> +		DPU_REG_WRITE(c, off, *lp++);

Nit: no need for lp here. Use array access like you do below.

> +		off += 4;
> +	}
> +
> +	off = DSC_RANGE_MIN_QP;
> +	for (i = 0; i < DSC_NUM_BUF_RANGES; i++) {
> +		DPU_REG_WRITE(c, off, rc[i].range_min_qp);
> +		off += 4;
> +	}
> +
> +	off = DSC_RANGE_MAX_QP;
> +	for (i = 0; i < 15; i++) {
> +		DPU_REG_WRITE(c, off, rc[i].range_max_qp);
> +		off += 4;
> +	}
> +
> +	off = DSC_RANGE_BPG_OFFSET;
> +	for (i = 0; i < 15; i++) {
> +		DPU_REG_WRITE(c, off, rc[i].range_bpg_offset);
> +		off += 4;
> +	}


> +}
> +
> +static struct dpu_dsc_cfg *_dsc_offset(enum dpu_dsc dsc,
> +				       struct dpu_mdss_cfg *m,
> +				       void __iomem *addr,
> +				       struct dpu_hw_blk_reg_map *b)
> +{
> +	int i;
> +
> +	for (i = 0; i < m->dsc_count; i++) {
> +		if (dsc == m->dsc[i].id) {
> +			b->base_off = addr;
> +			b->blk_off = m->dsc[i].base;
> +			b->length = m->dsc[i].len;
> +			b->hwversion = m->hwversion;
> +			b->log_mask = DPU_DBG_MASK_DSC;
> +			return &m->dsc[i];
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
> +static void _setup_dsc_ops(struct dpu_hw_dsc_ops *ops,
> +			   unsigned long cap)
> +{
> +	ops->dsc_disable = dpu_hw_dsc_disable;
> +	ops->dsc_config = dpu_hw_dsc_config;
> +	ops->dsc_config_thresh = dpu_hw_dsc_config_thresh;
> +};
> +
> +static struct dpu_hw_blk_ops dpu_hw_ops = {
> +	.start = NULL,
> +	.stop = NULL,
> +};
> +
> +struct dpu_hw_dsc *dpu_hw_dsc_init(enum dpu_dsc idx, void __iomem *addr,
> +				   struct dpu_mdss_cfg *m)
> +{
> +	struct dpu_hw_dsc *c;
> +	struct dpu_dsc_cfg *cfg;
> +
> +	c = kzalloc(sizeof(*c), GFP_KERNEL);
> +	if (!c)
> +		return ERR_PTR(-ENOMEM);
> +
> +	cfg = _dsc_offset(idx, m, addr, &c->hw);
> +	if (IS_ERR_OR_NULL(cfg)) {
> +		kfree(c);
> +		return ERR_PTR(-EINVAL);
> +	}
> +
> +	c->idx = idx;
> +	c->caps = cfg;
> +	_setup_dsc_ops(&c->ops, c->caps->features);
> +
> +	dpu_hw_blk_init(&c->base, DPU_HW_BLK_DSC, idx, &dpu_hw_ops);
> +
> +	return c;
> +}
> +
> +void dpu_hw_dsc_destroy(struct dpu_hw_dsc *dsc)
> +{
> +	if (dsc)
> +		dpu_hw_blk_destroy(&dsc->base);
> +	kfree(dsc);
> +}
> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.h
> new file mode 100644
> index 000000000000..c680fd948865
> --- /dev/null
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dsc.h
> @@ -0,0 +1,79 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/* Copyright (c) 2020, Linaro Limited */
> +
> +#ifndef _DPU_HW_DSC_H
> +#define _DPU_HW_DSC_H
> +
> +#include <drm/drm_dsc.h>
> +
> +#define DSC_MODE_SPLIT_PANEL            BIT(0)
> +#define DSC_MODE_MULTIPLEX              BIT(1)
> +#define DSC_MODE_VIDEO                  BIT(2)
> +
> +struct dpu_hw_dsc;
> +
> +/**
> + * struct dpu_hw_dsc_ops - interface to the dsc hardware driver functions
> + * Assumption is these functions will be called after clocks are enabled
> + */
> +struct dpu_hw_dsc_ops {
> +	/**
> +	 * dsc_disable - disable dsc
> +	 * @hw_dsc: Pointer to dsc context
> +	 */
> +	void (*dsc_disable)(struct dpu_hw_dsc *hw_dsc);
> +
> +	/**
> +	 * dsc_config - configures dsc encoder
> +	 * @hw_dsc: Pointer to dsc context
> +	 * @dsc: panel dsc parameters
> +	 * @mode: dsc topology mode to be set
> +	 * @ich_reset_override: option to reset ich
> +	 */
> +	void (*dsc_config)(struct dpu_hw_dsc *hw_dsc,
> +			   struct msm_display_dsc_config *dsc,
> +			   u32 mode, bool ich_reset_override);
> +
> +	/**
> +	 * dsc_config_thresh - programs panel thresholds
> +	 * @hw_dsc: Pointer to dsc context
> +	 * @dsc: panel dsc parameters
> +	 */
> +	void (*dsc_config_thresh)(struct dpu_hw_dsc *hw_dsc,
> +				  struct msm_display_dsc_config *dsc);
> +};
> +
> +struct dpu_hw_dsc {
> +	struct dpu_hw_blk base;
> +	struct dpu_hw_blk_reg_map hw;
> +
> +	/* dsc */
> +	enum dpu_dsc idx;
> +	const struct dpu_dsc_cfg *caps;
> +
> +	/* ops */
> +	struct dpu_hw_dsc_ops ops;
> +};
> +
> +/**
> + * dpu_hw_dsc_init - initializes the dsc block for the passed dsc idx.
> + * @idx:  DSC index for which driver object is required
> + * @addr: Mapped register io address of MDP
> + * @m:    Pointer to mdss catalog data
> + * Returns: Error code or allocated dpu_hw_dsc context
> + */
> +struct dpu_hw_dsc *dpu_hw_dsc_init(enum dpu_dsc idx, void __iomem *addr,
> +				   struct dpu_mdss_cfg *m);
> +
> +/**
> + * dpu_hw_dsc_destroy - destroys dsc driver context
> + * @dsc:   Pointer to dsc driver context returned by dpu_hw_dsc_init
> + */
> +void dpu_hw_dsc_destroy(struct dpu_hw_dsc *dsc);
> +
> +static inline struct dpu_hw_dsc *to_dpu_hw_dsc(struct dpu_hw_blk *hw)
> +{
> +	return container_of(hw, struct dpu_hw_dsc, base);
> +}
> +
> +#endif /* _DPU_HW_DSC_H */
> 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 09a3fb3e89f5..1b72c11090ee 100644
> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_mdss.h
> @@ -97,6 +97,7 @@ enum dpu_hw_blk_type {
>   	DPU_HW_BLK_WB,
>   	DPU_HW_BLK_DSPP,
>   	DPU_HW_BLK_MERGE_3D,
> +	DPU_HW_BLK_DSC,
>   	DPU_HW_BLK_MAX,
>   };
>   
> @@ -176,6 +177,17 @@ enum dpu_ctl {
>   	CTL_MAX
>   };
>   
> +enum dpu_dsc {
> +	DSC_NONE = 0,
> +	DSC_0,
> +	DSC_1,
> +	DSC_2,
> +	DSC_3,
> +	DSC_4,
> +	DSC_5,
> +	DSC_MAX
> +};
> +
>   enum dpu_pingpong {
>   	PINGPONG_0 = 1,
>   	PINGPONG_1,
> @@ -437,5 +449,6 @@ struct dpu_mdss_color {
>   #define DPU_DBG_MASK_VBIF     (1 << 8)
>   #define DPU_DBG_MASK_ROT      (1 << 9)
>   #define DPU_DBG_MASK_DSPP     (1 << 10)
> +#define DPU_DBG_MASK_DSC      (1 << 11)
>   
>   #endif  /* _DPU_HW_MDSS_H */
> 


-- 
With best wishes
Dmitry