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linux_dsm_epyc7002/drivers/gpu/drm/drm_dsc.c
Manasi Navare 05bad2357a drm/dsc: Add kernel documentation for DRM DP DSC helpers 
This patch adds appropriate kernel documentation for DRM DP helpers
used for enabling Display Stream compression functionality in
drm_dp_helper.h and drm_dp_helper.c as well as for the DSC spec
related structure definitions and helpers in drm_dsc.c and drm_dsc.h
Also add links between the functions and structures in the documentation.

v3:
* Fix the checkpatch warnings (Sean Paul)
v2:
* Add inline comments for longer structs (Daniel Vetter)
* Split the summary and description (Daniel Vetter)

Suggested-by: Daniel Vetter <daniel.vetter@intel.com>
Suggested-by: Sean Paul <sean@poorly.run>
Cc: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sean Paul <sean@poorly.run>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Acked-by: Sean Paul <sean@poorly.run>
Reviewed-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190206213148.21390-1-manasi.d.navare@intel.com
2019-02-08 13:38:51 -08:00

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// SPDX-License-Identifier: MIT
/*
* Copyright © 2018 Intel Corp
*
* Author:
* Manasi Navare <manasi.d.navare@intel.com>
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/byteorder/generic.h>
#include <drm/drm_dp_helper.h>
#include <drm/drm_dsc.h>
/**
* DOC: dsc helpers
*
* VESA specification for DP 1.4 adds a new feature called Display Stream
* Compression (DSC) used to compress the pixel bits before sending it on
* DP/eDP/MIPI DSI interface. DSC is required to be enabled so that the existing
* display interfaces can support high resolutions at higher frames rates uisng
* the maximum available link capacity of these interfaces.
*
* These functions contain some common logic and helpers to deal with VESA
* Display Stream Compression standard required for DSC on Display Port/eDP or
* MIPI display interfaces.
*/
/**
* drm_dsc_dp_pps_header_init() - Initializes the PPS Header
* for DisplayPort as per the DP 1.4 spec.
* @pps_sdp: Secondary data packet for DSC Picture Parameter Set
* as defined in &struct drm_dsc_pps_infoframe
*
* DP 1.4 spec defines the secondary data packet for sending the
* picture parameter infoframes from the source to the sink.
* This function populates the pps header defined in
* &struct drm_dsc_pps_infoframe as per the header bytes defined
* in &struct dp_sdp_header.
*/
void drm_dsc_dp_pps_header_init(struct drm_dsc_pps_infoframe *pps_sdp)
{
memset(&pps_sdp->pps_header, 0, sizeof(pps_sdp->pps_header));
pps_sdp->pps_header.HB1 = DP_SDP_PPS;
pps_sdp->pps_header.HB2 = DP_SDP_PPS_HEADER_PAYLOAD_BYTES_MINUS_1;
}
EXPORT_SYMBOL(drm_dsc_dp_pps_header_init);
/**
* drm_dsc_pps_infoframe_pack() - Populates the DSC PPS infoframe
*
* @pps_sdp:
* Secondary data packet for DSC Picture Parameter Set. This is defined
* by &struct drm_dsc_pps_infoframe
* @dsc_cfg:
* DSC Configuration data filled by driver as defined by
* &struct drm_dsc_config
*
* DSC source device sends a secondary data packet filled with all the
* picture parameter set (PPS) information required by the sink to decode
* the compressed frame. Driver populates the dsC PPS infoframe using the DSC
* configuration parameters in the order expected by the DSC Display Sink
* device. For the DSC, the sink device expects the PPS payload in the big
* endian format for the fields that span more than 1 byte.
*/
void drm_dsc_pps_infoframe_pack(struct drm_dsc_pps_infoframe *pps_sdp,
const struct drm_dsc_config *dsc_cfg)
{
int i;
/* Protect against someone accidently changing struct size */
BUILD_BUG_ON(sizeof(pps_sdp->pps_payload) !=
DP_SDP_PPS_HEADER_PAYLOAD_BYTES_MINUS_1 + 1);
memset(&pps_sdp->pps_payload, 0, sizeof(pps_sdp->pps_payload));
/* PPS 0 */
pps_sdp->pps_payload.dsc_version =
dsc_cfg->dsc_version_minor |
dsc_cfg->dsc_version_major << DSC_PPS_VERSION_MAJOR_SHIFT;
/* PPS 1, 2 is 0 */
/* PPS 3 */
pps_sdp->pps_payload.pps_3 =
dsc_cfg->line_buf_depth |
dsc_cfg->bits_per_component << DSC_PPS_BPC_SHIFT;
/* PPS 4 */
pps_sdp->pps_payload.pps_4 =
((dsc_cfg->bits_per_pixel & DSC_PPS_BPP_HIGH_MASK) >>
DSC_PPS_MSB_SHIFT) |
dsc_cfg->vbr_enable << DSC_PPS_VBR_EN_SHIFT |
dsc_cfg->enable422 << DSC_PPS_SIMPLE422_SHIFT |
dsc_cfg->convert_rgb << DSC_PPS_CONVERT_RGB_SHIFT |
dsc_cfg->block_pred_enable << DSC_PPS_BLOCK_PRED_EN_SHIFT;
/* PPS 5 */
pps_sdp->pps_payload.bits_per_pixel_low =
(dsc_cfg->bits_per_pixel & DSC_PPS_LSB_MASK);
/*
* The DSC panel expects the PPS packet to have big endian format
* for data spanning 2 bytes. Use a macro cpu_to_be16() to convert
* to big endian format. If format is little endian, it will swap
* bytes to convert to Big endian else keep it unchanged.
*/
/* PPS 6, 7 */
pps_sdp->pps_payload.pic_height = cpu_to_be16(dsc_cfg->pic_height);
/* PPS 8, 9 */
pps_sdp->pps_payload.pic_width = cpu_to_be16(dsc_cfg->pic_width);
/* PPS 10, 11 */
pps_sdp->pps_payload.slice_height = cpu_to_be16(dsc_cfg->slice_height);
/* PPS 12, 13 */
pps_sdp->pps_payload.slice_width = cpu_to_be16(dsc_cfg->slice_width);
/* PPS 14, 15 */
pps_sdp->pps_payload.chunk_size = cpu_to_be16(dsc_cfg->slice_chunk_size);
/* PPS 16 */
pps_sdp->pps_payload.initial_xmit_delay_high =
((dsc_cfg->initial_xmit_delay &
DSC_PPS_INIT_XMIT_DELAY_HIGH_MASK) >>
DSC_PPS_MSB_SHIFT);
/* PPS 17 */
pps_sdp->pps_payload.initial_xmit_delay_low =
(dsc_cfg->initial_xmit_delay & DSC_PPS_LSB_MASK);
/* PPS 18, 19 */
pps_sdp->pps_payload.initial_dec_delay =
cpu_to_be16(dsc_cfg->initial_dec_delay);
/* PPS 20 is 0 */
/* PPS 21 */
pps_sdp->pps_payload.initial_scale_value =
dsc_cfg->initial_scale_value;
/* PPS 22, 23 */
pps_sdp->pps_payload.scale_increment_interval =
cpu_to_be16(dsc_cfg->scale_increment_interval);
/* PPS 24 */
pps_sdp->pps_payload.scale_decrement_interval_high =
((dsc_cfg->scale_decrement_interval &
DSC_PPS_SCALE_DEC_INT_HIGH_MASK) >>
DSC_PPS_MSB_SHIFT);
/* PPS 25 */
pps_sdp->pps_payload.scale_decrement_interval_low =
(dsc_cfg->scale_decrement_interval & DSC_PPS_LSB_MASK);
/* PPS 26[7:0], PPS 27[7:5] RESERVED */
/* PPS 27 */
pps_sdp->pps_payload.first_line_bpg_offset =
dsc_cfg->first_line_bpg_offset;
/* PPS 28, 29 */
pps_sdp->pps_payload.nfl_bpg_offset =
cpu_to_be16(dsc_cfg->nfl_bpg_offset);
/* PPS 30, 31 */
pps_sdp->pps_payload.slice_bpg_offset =
cpu_to_be16(dsc_cfg->slice_bpg_offset);
/* PPS 32, 33 */
pps_sdp->pps_payload.initial_offset =
cpu_to_be16(dsc_cfg->initial_offset);
/* PPS 34, 35 */
pps_sdp->pps_payload.final_offset = cpu_to_be16(dsc_cfg->final_offset);
/* PPS 36 */
pps_sdp->pps_payload.flatness_min_qp = dsc_cfg->flatness_min_qp;
/* PPS 37 */
pps_sdp->pps_payload.flatness_max_qp = dsc_cfg->flatness_max_qp;
/* PPS 38, 39 */
pps_sdp->pps_payload.rc_model_size =
cpu_to_be16(DSC_RC_MODEL_SIZE_CONST);
/* PPS 40 */
pps_sdp->pps_payload.rc_edge_factor = DSC_RC_EDGE_FACTOR_CONST;
/* PPS 41 */
pps_sdp->pps_payload.rc_quant_incr_limit0 =
dsc_cfg->rc_quant_incr_limit0;
/* PPS 42 */
pps_sdp->pps_payload.rc_quant_incr_limit1 =
dsc_cfg->rc_quant_incr_limit1;
/* PPS 43 */
pps_sdp->pps_payload.rc_tgt_offset = DSC_RC_TGT_OFFSET_LO_CONST |
DSC_RC_TGT_OFFSET_HI_CONST << DSC_PPS_RC_TGT_OFFSET_HI_SHIFT;
/* PPS 44 - 57 */
for (i = 0; i < DSC_NUM_BUF_RANGES - 1; i++)
pps_sdp->pps_payload.rc_buf_thresh[i] =
dsc_cfg->rc_buf_thresh[i];
/* PPS 58 - 87 */
/*
* For DSC sink programming the RC Range parameter fields
* are as follows: Min_qp[15:11], max_qp[10:6], offset[5:0]
*/
for (i = 0; i < DSC_NUM_BUF_RANGES; i++) {
pps_sdp->pps_payload.rc_range_parameters[i] =
((dsc_cfg->rc_range_params[i].range_min_qp <<
DSC_PPS_RC_RANGE_MINQP_SHIFT) |
(dsc_cfg->rc_range_params[i].range_max_qp <<
DSC_PPS_RC_RANGE_MAXQP_SHIFT) |
(dsc_cfg->rc_range_params[i].range_bpg_offset));
pps_sdp->pps_payload.rc_range_parameters[i] =
cpu_to_be16(pps_sdp->pps_payload.rc_range_parameters[i]);
}
/* PPS 88 */
pps_sdp->pps_payload.native_422_420 = dsc_cfg->native_422 |
dsc_cfg->native_420 << DSC_PPS_NATIVE_420_SHIFT;
/* PPS 89 */
pps_sdp->pps_payload.second_line_bpg_offset =
dsc_cfg->second_line_bpg_offset;
/* PPS 90, 91 */
pps_sdp->pps_payload.nsl_bpg_offset =
cpu_to_be16(dsc_cfg->nsl_bpg_offset);
/* PPS 92, 93 */
pps_sdp->pps_payload.second_line_offset_adj =
cpu_to_be16(dsc_cfg->second_line_offset_adj);
/* PPS 94 - 127 are O */
}
EXPORT_SYMBOL(drm_dsc_pps_infoframe_pack);
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