Message-ID: <d5ee8233-66c8-9b88-417c-6cf9cc5c84fe@quicinc.com>
Date:   Fri, 24 Feb 2023 14:26:08 -0800
From:   Abhinav Kumar <quic_abhinavk@...cinc.com>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Kuogee Hsieh <quic_khsieh@...cinc.com>,
        <dri-devel@...ts.freedesktop.org>, <robdclark@...il.com>,
        <sean@...rly.run>, <swboyd@...omium.org>, <dianders@...omium.org>,
        <vkoul@...nel.org>, <daniel@...ll.ch>, <airlied@...il.com>,
        <agross@...nel.org>, <andersson@...nel.org>
CC:     <quic_sbillaka@...cinc.com>, <marijn.suijten@...ainline.org>,
        <freedreno@...ts.freedesktop.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/2] drm/msm/dpu: add dsc helper functions



On 2/24/2023 1:36 PM, Dmitry Baryshkov wrote:
> 24 февраля 2023 г. 23:23:03 GMT+02:00, Abhinav Kumar <quic_abhinavk@...cinc.com> пишет:
>>
>>
>> On 2/24/2023 1:13 PM, Dmitry Baryshkov wrote:
>>> On 24/02/2023 21:40, Kuogee Hsieh wrote:
>>>> Add DSC helper functions based on DSC configuration profiles to produce
>>>> DSC related runtime parameters through both table look up and runtime
>>>> calculation to support DSC on DPU.
>>>>
>>>> There are 6 different DSC configuration profiles are supported currently.
>>>> DSC configuration profiles are differiented by 5 keys, DSC version (V1.1),
>>>> chroma (444/422/420), colorspace (RGB/YUV), bpc(8/10),
>>>> bpp (6/7/7.5/8/9/10/12/15) and SCR (0/1).
>>>>
>>>> Only DSC version V1.1 added and V1.2 will be added later.
>>>
>>> These helpers should go to drivers/gpu/drm/display/drm_dsc_helper.c
>>> Also please check that they can be used for i915 or for amdgpu (ideally for both of them).
>>>
>>
>> No, it cannot. So each DSC encoder parameter is calculated based on the HW core which is being used.
>>
>> They all get packed to the same DSC structure which is the struct drm_dsc_config but the way the parameters are computed is specific to the HW.
>>
>> This DPU file helper still uses the drm_dsc_helper's drm_dsc_compute_rc_parameters() like all other vendors do but the parameters themselves are very HW specific and belong to each vendor's dir.
>>
>> This is not unique to MSM.
>>
>> Lets take a few other examples:
>>
>> AMD: https://gitlab.freedesktop.org/drm/msm/-/blob/msm-next/drivers/gpu/drm/amd/display/dc/dml/dsc/rc_calc_fpu.c#L165
>>
>> i915: https://gitlab.freedesktop.org/drm/msm/-/blob/msm-next/drivers/gpu/drm/i915/display/intel_vdsc.c#L379
> 
> I checked several values here. Intel driver defines more bpc/bpp combinations, but the ones which are defined in intel_vdsc and in this patch seem to match. If there are major differences there, please point me to the exact case.
> 
> I remember that AMD driver might have different values.
> 

Some values in the rc_params table do match. But the rc_buf_thresh[] doesnt.

https://gitlab.freedesktop.org/drm/msm/-/blob/msm-next/drivers/gpu/drm/i915/display/intel_vdsc.c#L40

Vs

+static u16 dpu_dsc_rc_buf_thresh[DSC_NUM_BUF_RANGES - 1] = {
+		0x0e, 0x1c, 0x2a, 0x38, 0x46, 0x54,
+		0x62, 0x69, 0x70, 0x77, 0x79, 0x7b, 0x7d, 0x7e
+};

I dont know the AMD calculation very well to say that moving this to the 
helper is going to help.

Also, i think its too risky to change other drivers to use whatever math 
we put in the drm_dsc_helper to compute thr RC params because their code 
might be computing and using this tables differently.

Its too much ownership for MSM developers to move this to drm_dsc_helper 
and own that as it might cause breakage of basic DSC even if some values 
are repeated.

I would prefer to keep it in the msm code but in a top level directory 
so that we dont have to make DSI dependent on DPU.


> 
>>
>> All vendors compute the values differently and eventually call drm_dsc_compute_rc_parameters()
>>
>>> I didn't check the tables against the standard (or against the current source code), will do that later.
>>>
>>>>
>>>> Signed-off-by: Kuogee Hsieh <quic_khsieh@...cinc.com>
>>>> ---
>>>>    drivers/gpu/drm/msm/Makefile                   |   1 +
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_dsc_helper.c | 209 +++++++++++++++++++++++++
>>>>    drivers/gpu/drm/msm/disp/dpu1/dpu_dsc_helper.h |  34 ++++
>>>>    3 files changed, 244 insertions(+)
>>>>    create mode 100644 drivers/gpu/drm/msm/disp/dpu1/dpu_dsc_helper.c
>>>>    create mode 100644 drivers/gpu/drm/msm/disp/dpu1/dpu_dsc_helper.h
>>>>
>>>> diff --git a/drivers/gpu/drm/msm/Makefile b/drivers/gpu/drm/msm/Makefile
>>>> index 7274c412..28cf52b 100644
>>>> --- a/drivers/gpu/drm/msm/Makefile
>>>> +++ b/drivers/gpu/drm/msm/Makefile
>>>> @@ -65,6 +65,7 @@ msm-$(CONFIG_DRM_MSM_DPU) += \
>>>>        disp/dpu1/dpu_hw_catalog.o \
>>>>        disp/dpu1/dpu_hw_ctl.o \
>>>>        disp/dpu1/dpu_hw_dsc.o \
>>>> +    disp/dpu1/dpu_dsc_helper.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_dsc_helper.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_dsc_helper.c
>>>> new file mode 100644
>>>> index 00000000..88207e9
>>>> --- /dev/null
>>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_dsc_helper.c
>>>> @@ -0,0 +1,209 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +/*
>>>> + * Copyright (c) 2023. Qualcomm Innovation Center, Inc. All rights reserved
>>>> + */
>>>> +
>>>> +#include <drm/display/drm_dsc_helper.h>
>>>> +#include "msm_drv.h"
>>>> +#include "dpu_kms.h"
>>>> +#include "dpu_hw_dsc.h"
>>>> +#include "dpu_dsc_helper.h"
>>>> +
>>>> +
>>>
>>> Extra empty line
>>>
>>>> +#define DPU_DSC_PPS_SIZE       128
>>>> +
>>>> +enum dpu_dsc_ratio_type {
>>>> +    DSC_V11_8BPC_8BPP,
>>>> +    DSC_V11_10BPC_8BPP,
>>>> +    DSC_V11_10BPC_10BPP,
>>>> +    DSC_V11_SCR1_8BPC_8BPP,
>>>> +    DSC_V11_SCR1_10BPC_8BPP,
>>>> +    DSC_V11_SCR1_10BPC_10BPP,
>>>> +    DSC_RATIO_TYPE_MAX
>>>> +};
>>>> +
>>>> +
>>>> +static u16 dpu_dsc_rc_buf_thresh[DSC_NUM_BUF_RANGES - 1] = {
>>>> +        0x0e, 0x1c, 0x2a, 0x38, 0x46, 0x54,
>>>> +        0x62, 0x69, 0x70, 0x77, 0x79, 0x7b, 0x7d, 0x7e
>>>
>>> Weird indentation
>>>
>>>> +};
>>>> +
>>>> +/*
>>>> + * Rate control - Min QP values for each ratio type in dpu_dsc_ratio_type
>>>> + */
>>>> +static char dpu_dsc_rc_range_min_qp[DSC_RATIO_TYPE_MAX][DSC_NUM_BUF_RANGES] = {
>>>> +    /* DSC v1.1 */
>>>> +    {0, 0, 1, 1, 3, 3, 3, 3, 3, 3, 5, 5, 5, 7, 13},
>>>> +    {0, 4, 5, 5, 7, 7, 7, 7, 7, 7, 9, 9, 9, 11, 17},
>>>> +    {0, 4, 5, 6, 7, 7, 7, 7, 7, 7, 9, 9, 9, 11, 15},
>>>> +    /* DSC v1.1 SCR and DSC v1.2 RGB 444 */
>>>
>>> What is SCR? Is there any reason to use older min/max Qp params instead of always using the ones from the VESA-DSC-1.1 standard?
>>>
>>>> +    {0, 0, 1, 1, 3, 3, 3, 3, 3, 3, 5, 5, 5, 9, 12},
>>>> +    {0, 4, 5, 5, 7, 7, 7, 7, 7, 7, 9, 9, 9, 13, 16},
>>>> +    {0, 4, 5, 6, 7, 7, 7, 7, 7, 7, 9, 9, 9, 11, 15},
>>>> +};
>>>> +
>>>> +/*
>>>> + * Rate control - Max QP values for each ratio type in dpu_dsc_ratio_type
>>>> + */
>>>> +static char dpu_dsc_rc_range_max_qp[DSC_RATIO_TYPE_MAX][DSC_NUM_BUF_RANGES] = {
>>>> +    /* DSC v1.1 */
>>>> +    {4, 4, 5, 6, 7, 7, 7, 8, 9, 10, 11, 12, 13, 13, 15},
>>>> +    {4, 8, 9, 10, 11, 11, 11, 12, 13, 14, 15, 16, 17, 17, 19},
>>>> +    {7, 8, 9, 10, 11, 11, 11, 12, 13, 13, 14, 14, 15, 15, 16},
>>>> +    /* DSC v1.1 SCR and DSC v1.2 RGB 444 */
>>>> +    {4, 4, 5, 6, 7, 7, 7, 8, 9, 10, 10, 11, 11, 12, 13},
>>>> +    {8, 8, 9, 10, 11, 11, 11, 12, 13, 14, 14, 15, 15, 16, 17},
>>>> +    {7, 8, 9, 10, 11, 11, 11, 12, 13, 13, 14, 14, 15, 15, 16},
>>>> +};
>>>> +
>>>> +/*
>>>> + * Rate control - bpg offset values for each ratio type in dpu_dsc_ratio_type
>>>> + */
>>>> +static char dpu_dsc_rc_range_bpg[DSC_RATIO_TYPE_MAX][DSC_NUM_BUF_RANGES] = {
>>>> +    /* DSC v1.1 */
>>>> +    {2, 0, 0, -2, -4, -6, -8, -8, -8, -10, -10, -12, -12, -12, -12},
>>>> +    {2, 0, 0, -2, -4, -6, -8, -8, -8, -10, -10, -12, -12, -12, -12},
>>>> +    {2, 0, 0, -2, -4, -6, -8, -8, -8, -10, -10, -10, -12, -12, -12},
>>>> +    /* DSC v1.1 SCR and DSC V1.2 RGB 444 */
>>>> +    {2, 0, 0, -2, -4, -6, -8, -8, -8, -10, -10, -12, -12, -12, -12},
>>>> +    {2, 0, 0, -2, -4, -6, -8, -8, -8, -10, -10, -12, -12, -12, -12},
>>>> +    {2, 0, 0, -2, -4, -6, -8, -8, -8, -10, -10, -10, -12, -12, -12},
>>>> +};
>>>> +
>>>> +static struct dpu_dsc_rc_init_params_lut {
>>>> +    u32 rc_quant_incr_limit0;
>>>> +    u32 rc_quant_incr_limit1;
>>>> +    u32 initial_fullness_offset;
>>>> +    u32 initial_xmit_delay;
>>>> +    u32 second_line_bpg_offset;
>>>> +    u32 second_line_offset_adj;
>>>> +    u32 flatness_min_qp;
>>>> +    u32 flatness_max_qp;
>>>> +}  dpu_dsc_rc_init_param_lut[] = {
>>>> +    /* DSC v1.1 */
>>>> +    {11, 11, 6144, 512, 0, 0, 3, 12}, /* DSC_V11_8BPC_8BPP */
>>>> +    {15, 15, 6144, 512, 0, 0, 7, 16}, /* DSC_V11_10BPC_8BPP */
>>>> +    {15, 15, 5632, 410, 0, 0, 7, 16}, /* DSC_V11_10BPC_10BPP */
>>>> +    /* DSC v1.1 SCR and DSC v1.2 RGB 444 */
>>>> +    {11, 11, 6144, 512, 0, 0, 3, 12}, /* DSC_V12_444_8BPC_8BPP or DSC_V11_SCR1_8BPC_8BPP */
>>>> +    {15, 15, 6144, 512, 0, 0, 7, 16}, /* DSC_V12_444_10BPC_8BPP or DSC_V11_SCR1_10BPC_8BPP */
>>>> +    {15, 15, 5632, 410, 0, 0, 7, 16}, /* DSC_V12_444_10BPC_10BPP or DSC_V11_SCR1_10BPC_10BPP */
>>>> +};
>>>> +
>>>> +/**
>>>> + * Maps to lookup the dpu_dsc_ratio_type index used in rate control tables
>>>> + */
>>>> +static struct dpu_dsc_table_index_lut {
>>>> +    u32 fmt;
>>>> +    u32 scr_ver;
>>>> +    u32 minor_ver;
>>>> +    u32 bpc;
>>>> +    u32 bpp;
>>>> +    u32 type;
>>>> +} dpu_dsc_index_map[] = {
>>>> +    /* DSC 1.1 formats - scr version is considered */
>>>> +    {DPU_DSC_CHROMA_444, 0, 1, 8, 8, DSC_V11_8BPC_8BPP},
>>>> +    {DPU_DSC_CHROMA_444, 0, 1, 10, 8, DSC_V11_10BPC_8BPP},
>>>> +    {DPU_DSC_CHROMA_444, 0, 1, 10, 10, DSC_V11_10BPC_10BPP},
>>>> +    {DPU_DSC_CHROMA_444, 1, 1, 8, 8, DSC_V11_SCR1_8BPC_8BPP},
>>>> +    {DPU_DSC_CHROMA_444, 1, 1, 10, 8, DSC_V11_SCR1_10BPC_8BPP},
>>>> +    {DPU_DSC_CHROMA_444, 1, 1, 10, 10, DSC_V11_SCR1_10BPC_10BPP},
>>>> +};
>>>> +
>>>> +static int _get_rc_table_index(struct drm_dsc_config *dsc, int scr_ver)
>>>> +{
>>>> +    u32 bpp, bpc, i, fmt = DPU_DSC_CHROMA_444;
>>>> +
>>>> +    if (dsc->dsc_version_major != 0x1) {
>>>> +        DPU_ERROR("unsupported major version %d\n",
>>>> +                dsc->dsc_version_major);
>>>> +        return -EINVAL;
>>>> +    }
>>>> +
>>>> +    bpc = dsc->bits_per_component;
>>>> +    bpp = DSC_BPP(*dsc);
>>>
>>> Just inline the macro.
>>>
>>>> +
>>>> +    if (dsc->native_422)
>>>> +        fmt = DPU_DSC_CHROMA_422;
>>>> +    else if (dsc->native_420)
>>>> +        fmt = DPU_DSC_CHROMA_420;
>>>> +
>>>> +
>>>> +    for (i = 0; i < ARRAY_SIZE(dpu_dsc_index_map); i++) {
>>>> +        if (dsc->dsc_version_minor == dpu_dsc_index_map[i].minor_ver &&
>>>> +                fmt ==  dpu_dsc_index_map[i].fmt &&
>>>> +                bpc == dpu_dsc_index_map[i].bpc &&
>>>> +                bpp == dpu_dsc_index_map[i].bpp &&
>>>> +                (dsc->dsc_version_minor != 0x1 ||
>>>> +                    scr_ver == dpu_dsc_index_map[i].scr_ver))
>>>> +            return dpu_dsc_index_map[i].type;
>>>> +    }
>>>> +
>>>> +    DPU_ERROR("unsupported DSC v%d.%dr%d, bpc:%d, bpp:%d, fmt:0x%x\n",
>>>> +            dsc->dsc_version_major, dsc->dsc_version_minor,
>>>> +            scr_ver, bpc, bpp, fmt);
>>>> +    return -EINVAL;
>>>> +}
>>>> +
>>>> +int dpu_dsc_populate_dsc_config(struct drm_dsc_config *dsc, int scr_ver)
>>>> +{
>>>> +    int bpp, bpc;
>>>> +    struct dpu_dsc_rc_init_params_lut *rc_param_lut;
>>>> +    int i, ratio_idx;
>>>> +
>>>> +    dsc->rc_model_size = 8192;
>>>> +
>>>> +    if ((dsc->dsc_version_major == 0x1) &&
>>>> +            (dsc->dsc_version_minor == 0x1)) {
>>>
>>> indent to the opening bracket please, so that '(dsc' on both lines start on the same position.
>>>
>>>> +        if (scr_ver == 0x1)
>>>> +            dsc->first_line_bpg_offset = 15;
>>>> +        else
>>>> +            dsc->first_line_bpg_offset = 12;
>>>> +    }
>>>> +
>>>> +    dsc->rc_edge_factor = 6;
>>>> +    dsc->rc_tgt_offset_high = 3;
>>>> +    dsc->rc_tgt_offset_low = 3;
>>>> +    dsc->simple_422 = 0;
>>>> +    dsc->convert_rgb = !(dsc->native_422 | dsc->native_420);
>>>> +    dsc->vbr_enable = 0;
>>>> +
>>>> +    bpp = DSC_BPP(*dsc);
>>>
>>> inline the macro.
>>>
>>>> +    bpc = dsc->bits_per_component;
>>>> +
>>>> +    ratio_idx = _get_rc_table_index(dsc, scr_ver);
>>>> +    if ((ratio_idx < 0) || (ratio_idx >= DSC_RATIO_TYPE_MAX))
>>>> +        return -EINVAL;
>>>> +
>>>> +
>>>> +    for (i = 0; i < DSC_NUM_BUF_RANGES - 1; i++)
>>>> +        dsc->rc_buf_thresh[i] = dpu_dsc_rc_buf_thresh[i];
>>>
>>> Can we use memcpy?
>>>
>>>> +
>>>> +    for (i = 0; i < DSC_NUM_BUF_RANGES; i++) {
>>>> +        dsc->rc_range_params[i].range_min_qp =
>>>> +            dpu_dsc_rc_range_min_qp[ratio_idx][i];
>>>> +        dsc->rc_range_params[i].range_max_qp =
>>>> +            dpu_dsc_rc_range_max_qp[ratio_idx][i];
>>>> +        dsc->rc_range_params[i].range_bpg_offset =
>>>> +            dpu_dsc_rc_range_bpg[ratio_idx][i];
>>>> +    }
>>>> +
>>>> +    rc_param_lut = &dpu_dsc_rc_init_param_lut[ratio_idx];
>>>> +    dsc->rc_quant_incr_limit0 = rc_param_lut->rc_quant_incr_limit0;
>>>> +    dsc->rc_quant_incr_limit1 = rc_param_lut->rc_quant_incr_limit1;
>>>> +    dsc->initial_offset = rc_param_lut->initial_fullness_offset;
>>>> +    dsc->initial_xmit_delay = rc_param_lut->initial_xmit_delay;
>>>> +    dsc->second_line_bpg_offset = rc_param_lut->second_line_bpg_offset;
>>>> +    dsc->second_line_offset_adj = rc_param_lut->second_line_offset_adj;
>>>> +    dsc->flatness_min_qp = rc_param_lut->flatness_min_qp;
>>>> +    dsc->flatness_max_qp = rc_param_lut->flatness_max_qp;
>>>> +
>>>> +
>>>> +    dsc->line_buf_depth = bpc + 1;
>>>> +    dsc->mux_word_size = bpc > 10 ? DSC_MUX_WORD_SIZE_12_BPC : DSC_MUX_WORD_SIZE_8_10_BPC;
>>>> +
>>>> +    dsc->initial_scale_value = 8 * dsc->rc_model_size /
>>>> +            (dsc->rc_model_size - dsc->initial_offset);
>>>> +
>>>> +        return drm_dsc_compute_rc_parameters(dsc);
>>>
>>> Indentation is wrong
>>>
>>>> +}
>>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_dsc_helper.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_dsc_helper.h
>>>> new file mode 100644
>>>> index 00000000..4a23e02
>>>> --- /dev/null
>>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_dsc_helper.h
>>>> @@ -0,0 +1,34 @@
>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>> +/*
>>>> + * Copyright (c) 2023. Qualcomm Innovation Center, Inc. All rights reserved
>>>> + */
>>>> +
>>>> +#ifndef __DPU_DSC_HELPER_H__
>>>> +#define __DPU_DSC_HELPER_H__
>>>> +
>>>> +#include "msm_drv.h"
>>>> +
>>>> +#define DSC_1_1_PPS_PARAMETER_SET_ELEMENTS   88
>>>
>>> What is this? Does it need to be global?
>>>
>>>> +
>>>> +/**
>>>> + * Bits/pixel target >> 4  (removing the fractional bits)
>>>> + * returns the integer bpp value from the drm_dsc_config struct
>>>> + */
>>>> +#define DSC_BPP(config) ((config).bits_per_pixel >> 4)
>>>> +
>>>> +enum dpu_dsc_chroma {
>>>> +    DPU_DSC_CHROMA_444,
>>>> +    DPU_DSC_CHROMA_422,
>>>> +    DPU_DSC_CHROMA_420,
>>>> +};
>>>
>>> I think this enum is also not used outside of your helpers.
>>>
>>>> +
>>>> +int dpu_dsc_populate_dsc_config(struct drm_dsc_config *dsc, int scr_ver);
>>>> +
>>>> +bool dpu_dsc_ich_reset_override_needed(bool pu_en, struct drm_dsc_config *dsc);
>>>
>>> Unused
>>>
>>>> +
>>>> +int dpu_dsc_initial_line_calc( u32 num_active_ss_per_enc,
>>>> +                struct drm_dsc_config *dsc,
>>>> +                int enc_ip_width, int dsc_cmn_mode);
>>>
>>> Unused
>>>
>>>> +
>>>> +#endif /* __DPU_DSC_HELPER_H__ */
>>>> +
>>>
> 

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