linux-imx

// 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 */