// 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/display/drm_dp_helper.h>
#include <drm/display/drm_dsc_helper.h>
#include <drm/drm_print.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_header: Secondary data packet header for DSC Picture
* Parameter Set as defined in &struct dp_sdp_header
*
* 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 SDP header defined in
* &struct dp_sdp_header.
*/
void drm_dsc_dp_pps_header_init(struct dp_sdp_header *pps_header)
{
memset(pps_header, 0, sizeof(*pps_header));
pps_header->HB1 = DP_SDP_PPS;
pps_header->HB2 = DP_SDP_PPS_HEADER_PAYLOAD_BYTES_MINUS_1;
}
EXPORT_SYMBOL(drm_dsc_dp_pps_header_init);
/**
* drm_dsc_dp_rc_buffer_size - get rc buffer size in bytes
* @rc_buffer_block_size: block size code, according to DPCD offset 62h
* @rc_buffer_size: number of blocks - 1, according to DPCD offset 63h
*
* return:
* buffer size in bytes, or 0 on invalid input
*/
int drm_dsc_dp_rc_buffer_size(u8 rc_buffer_block_size, u8 rc_buffer_size)
{
int size = 1024 * (rc_buffer_size + 1);
switch (rc_buffer_block_size) {
case DP_DSC_RC_BUF_BLK_SIZE_1:
return 1 * size;
case DP_DSC_RC_BUF_BLK_SIZE_4:
return 4 * size;
case DP_DSC_RC_BUF_BLK_SIZE_16:
return 16 * size;
case DP_DSC_RC_BUF_BLK_SIZE_64:
return 64 * size;
default:
return 0;
}
}
EXPORT_SYMBOL(drm_dsc_dp_rc_buffer_size);
/**
* drm_dsc_pps_payload_pack() - Populates the DSC PPS
*
* @pps_payload:
* Bitwise struct for DSC Picture Parameter Set. This is defined
* by &struct drm_dsc_picture_parameter_set
* @dsc_cfg:
* DSC Configuration data filled by driver as defined by
* &struct 