hda_eld.c

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/*
 * Generic routines and proc interface for ELD(EDID Like Data) information
 *
 * Copyright(c) 2008 Intel Corporation.
 *
 * Authors:
 *      Wu Fengguang <[email protected]>
 *
 *  This driver is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This driver is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <sound/core.h>
#include <asm/unaligned.h>
#include "hda_codec.h"
#include "hda_local.h"

enum eld_versions {
    ELD_VER_CEA_861D    = 2,
    ELD_VER_PARTIAL     = 31,
};

enum cea_edid_versions {
    CEA_EDID_VER_NONE   = 0,
    CEA_EDID_VER_CEA861 = 1,
    CEA_EDID_VER_CEA861A    = 2,
    CEA_EDID_VER_CEA861BCD  = 3,
    CEA_EDID_VER_RESERVED   = 4,
};

static char *cea_speaker_allocation_names[] = {
    /*  0 */ "FL/FR",
    /*  1 */ "LFE",
    /*  2 */ "FC",
    /*  3 */ "RL/RR",
    /*  4 */ "RC",
    /*  5 */ "FLC/FRC",
    /*  6 */ "RLC/RRC",
    /*  7 */ "FLW/FRW",
    /*  8 */ "FLH/FRH",
    /*  9 */ "TC",
    /* 10 */ "FCH",
};

static char *eld_connection_type_names[4] = {
    "HDMI",
    "DisplayPort",
    "2-reserved",
    "3-reserved"
};

enum cea_audio_coding_types {
    AUDIO_CODING_TYPE_REF_STREAM_HEADER =  0,
    AUDIO_CODING_TYPE_LPCM          =  1,
    AUDIO_CODING_TYPE_AC3           =  2,
    AUDIO_CODING_TYPE_MPEG1         =  3,
    AUDIO_CODING_TYPE_MP3           =  4,
    AUDIO_CODING_TYPE_MPEG2         =  5,
    AUDIO_CODING_TYPE_AACLC         =  6,
    AUDIO_CODING_TYPE_DTS           =  7,
    AUDIO_CODING_TYPE_ATRAC         =  8,
    AUDIO_CODING_TYPE_SACD          =  9,
    AUDIO_CODING_TYPE_EAC3          = 10,
    AUDIO_CODING_TYPE_DTS_HD        = 11,
    AUDIO_CODING_TYPE_MLP           = 12,
    AUDIO_CODING_TYPE_DST           = 13,
    AUDIO_CODING_TYPE_WMAPRO        = 14,
    AUDIO_CODING_TYPE_REF_CXT       = 15,
    /* also include valid xtypes below */
    AUDIO_CODING_TYPE_HE_AAC        = 15,
    AUDIO_CODING_TYPE_HE_AAC2       = 16,
    AUDIO_CODING_TYPE_MPEG_SURROUND     = 17,
};

enum cea_audio_coding_xtypes {
    AUDIO_CODING_XTYPE_HE_REF_CT        = 0,
    AUDIO_CODING_XTYPE_HE_AAC       = 1,
    AUDIO_CODING_XTYPE_HE_AAC2      = 2,
    AUDIO_CODING_XTYPE_MPEG_SURROUND    = 3,
    AUDIO_CODING_XTYPE_FIRST_RESERVED   = 4,
};

static char *cea_audio_coding_type_names[] = {
    /*  0 */ "undefined",
    /*  1 */ "LPCM",
    /*  2 */ "AC-3",
    /*  3 */ "MPEG1",
    /*  4 */ "MP3",
    /*  5 */ "MPEG2",
    /*  6 */ "AAC-LC",
    /*  7 */ "DTS",
    /*  8 */ "ATRAC",
    /*  9 */ "DSD (One Bit Audio)",
    /* 10 */ "E-AC-3/DD+ (Dolby Digital Plus)",
    /* 11 */ "DTS-HD",
    /* 12 */ "MLP (Dolby TrueHD)",
    /* 13 */ "DST",
    /* 14 */ "WMAPro",
    /* 15 */ "HE-AAC",
    /* 16 */ "HE-AACv2",
    /* 17 */ "MPEG Surround",
};

/*
 * The following two lists are shared between
 *  - HDMI audio InfoFrame (source to sink)
 *  - CEA E-EDID Extension (sink to source)
 */

/*
 * SS1:SS0 index => sample size
 */
static int cea_sample_sizes[4] = {
    0,          /* 0: Refer to Stream Header */
    AC_SUPPCM_BITS_16,  /* 1: 16 bits */
    AC_SUPPCM_BITS_20,  /* 2: 20 bits */
    AC_SUPPCM_BITS_24,  /* 3: 24 bits */
};

/*
 * SF2:SF1:SF0 index => sampling frequency
 */
static int cea_sampling_frequencies[8] = {
    0,          /* 0: Refer to Stream Header */
    SNDRV_PCM_RATE_32000,   /* 1:  32000Hz */
    SNDRV_PCM_RATE_44100,   /* 2:  44100Hz */
    SNDRV_PCM_RATE_48000,   /* 3:  48000Hz */
    SNDRV_PCM_RATE_88200,   /* 4:  88200Hz */
    SNDRV_PCM_RATE_96000,   /* 5:  96000Hz */
    SNDRV_PCM_RATE_176400,  /* 6: 176400Hz */
    SNDRV_PCM_RATE_192000,  /* 7: 192000Hz */
};

static unsigned int hdmi_get_eld_data(struct hda_codec *codec, hda_nid_t nid,
                    int byte_index)
{
    unsigned int val;

    val = snd_hda_codec_read(codec, nid, 0,
                    AC_VERB_GET_HDMI_ELDD, byte_index);
#ifdef BE_PARANOID
    printk(KERN_INFO "HDMI: ELD data byte %d: 0x%x\n", byte_index, val);
#endif
    return val;
}

#define GRAB_BITS(buf, byte, lowbit, bits)      \
({                          \
    BUILD_BUG_ON(lowbit > 7);           \
    BUILD_BUG_ON(bits > 8);             \
    BUILD_BUG_ON(bits <= 0);            \
                            \
    (buf[byte] >> (lowbit)) & ((1 << (bits)) - 1);  \
})

static void hdmi_update_short_audio_desc(struct cea_sad *a,
                     const unsigned char *buf)
{
    int i;
    int val;

    val = GRAB_BITS(buf, 1, 0, 7);
    a->rates = 0;
    for (i = 0; i < 7; i++)
        if (val & (1 << i))
            a->rates |= cea_sampling_frequencies[i + 1];

    a->channels = GRAB_BITS(buf, 0, 0, 3);
    a->channels++;

    a->sample_bits = 0;
    a->max_bitrate = 0;

    a->format = GRAB_BITS(buf, 0, 3, 4);
    switch (a->format) {
    case AUDIO_CODING_TYPE_REF_STREAM_HEADER:
        snd_printd(KERN_INFO
                "HDMI: audio coding type 0 not expected\n");
        break;

    case AUDIO_CODING_TYPE_LPCM:
        val = GRAB_BITS(buf, 2, 0, 3);
        for (i = 0; i < 3; i++)
            if (val & (1 << i))
                a->sample_bits |= cea_sample_sizes[i + 1];
        break;

    case AUDIO_CODING_TYPE_AC3:
    case AUDIO_CODING_TYPE_MPEG1:
    case AUDIO_CODING_TYPE_MP3:
    case AUDIO_CODING_TYPE_MPEG2:
    case AUDIO_CODING_TYPE_AACLC:
    case AUDIO_CODING_TYPE_DTS:
    case AUDIO_CODING_TYPE_ATRAC:
        a->max_bitrate = GRAB_BITS(buf, 2, 0, 8);
        a->max_bitrate *= 8000;
        break;

    case AUDIO_CODING_TYPE_SACD:
        break;

    case AUDIO_CODING_TYPE_EAC3:
        break;

    case AUDIO_CODING_TYPE_DTS_HD:
        break;

    case AUDIO_CODING_TYPE_MLP:
        break;

    case AUDIO_CODING_TYPE_DST:
        break;

    case AUDIO_CODING_TYPE_WMAPRO:
        a->profile = GRAB_BITS(buf, 2, 0, 3);
        break;

    case AUDIO_CODING_TYPE_REF_CXT:
        a->format = GRAB_BITS(buf, 2, 3, 5);
        if (a->format == AUDIO_CODING_XTYPE_HE_REF_CT ||
            a->format >= AUDIO_CODING_XTYPE_FIRST_RESERVED) {
            snd_printd(KERN_INFO
                "HDMI: audio coding xtype %d not expected\n",
                a->format);
            a->format = 0;
        } else
            a->format += AUDIO_CODING_TYPE_HE_AAC -
                     AUDIO_CODING_XTYPE_HE_AAC;
        break;
    }
}

/*
 * Be careful, ELD buf could be totally rubbish!
 */
static int hdmi_update_eld(struct hdmi_eld *e,
               const unsigned char *buf, int size)
{
    int mnl;
    int i;

    e->eld_ver = GRAB_BITS(buf, 0, 3, 5);
    if (e->eld_ver != ELD_VER_CEA_861D &&
        e->eld_ver != ELD_VER_PARTIAL) {
        snd_printd(KERN_INFO "HDMI: Unknown ELD version %d\n",
                                e->eld_ver);
        goto out_fail;
    }

    e->eld_size = size;
    e->baseline_len = GRAB_BITS(buf, 2, 0, 8);
    mnl     = GRAB_BITS(buf, 4, 0, 5);
    e->cea_edid_ver = GRAB_BITS(buf, 4, 5, 3);

    e->support_hdcp = GRAB_BITS(buf, 5, 0, 1);
    e->support_ai   = GRAB_BITS(buf, 5, 1, 1);
    e->conn_type    = GRAB_BITS(buf, 5, 2, 2);
    e->sad_count    = GRAB_BITS(buf, 5, 4, 4);

    e->aud_synch_delay = GRAB_BITS(buf, 6, 0, 8) * 2;
    e->spk_alloc    = GRAB_BITS(buf, 7, 0, 7);

    e->port_id    = get_unaligned_le64(buf + 8);

    /* not specified, but the spec's tendency is little endian */
    e->manufacture_id = get_unaligned_le16(buf + 16);
    e->product_id     = get_unaligned_le16(buf + 18);

    if (mnl > ELD_MAX_MNL) {
        snd_printd(KERN_INFO "HDMI: MNL is reserved value %d\n", mnl);
        goto out_fail;
    } else if (ELD_FIXED_BYTES + mnl > size) {
        snd_printd(KERN_INFO "HDMI: out of range MNL %d\n", mnl);
        goto out_fail;
    } else
        strlcpy(e->monitor_name, buf + ELD_FIXED_BYTES, mnl + 1);

    for (i = 0; i < e->sad_count; i++) {
        if (ELD_FIXED_BYTES + mnl + 3 * (i + 1) > size) {
            snd_printd(KERN_INFO "HDMI: out of range SAD %d\n", i);
            goto out_fail;
        }
        hdmi_update_short_audio_desc(e->sad + i,
                    buf + ELD_FIXED_BYTES + mnl + 3 * i);
    }

    /*
     * HDMI sink's ELD info cannot always be retrieved for now, e.g.
     * in console or for audio devices. Assume the highest speakers
     * configuration, to _not_ prohibit multi-channel audio playback.
     */
    if (!e->spk_alloc)
        e->spk_alloc = 0xffff;

    e->eld_valid = true;
    return 0;

out_fail:
    return -EINVAL;
}

int snd_hdmi_get_eld_size(struct hda_codec *codec, hda_nid_t nid)
{
    return snd_hda_codec_read(codec, nid, 0, AC_VERB_GET_HDMI_DIP_SIZE,
                         AC_DIPSIZE_ELD_BUF);
}

int snd_hdmi_get_eld(struct hdmi_eld *eld,
             struct hda_codec *codec, hda_nid_t nid)
{
    int i;
    int ret;
    int size;
    unsigned char *buf;

    /*
     * ELD size is initialized to zero in caller function. If no errors and
     * ELD is valid, actual eld_size is assigned in hdmi_update_eld()
     */

    size = snd_hdmi_get_eld_size(codec, nid);
    if (size == 0) {
        /* wfg: workaround for ASUS P5E-VM HDMI board */
        snd_printd(KERN_INFO "HDMI: ELD buf size is 0, force 128\n");
        size = 128;
    }
    if (size < ELD_FIXED_BYTES || size > ELD_MAX_SIZE) {
        snd_printd(KERN_INFO "HDMI: invalid ELD buf size %d\n", size);
        return -ERANGE;
    }

    /* set ELD buffer */
    buf = eld->eld_buffer;

    for (i = 0; i < size; i++) {
        unsigned int val = hdmi_get_eld_data(codec, nid, i);
        /*
         * Graphics driver might be writing to ELD buffer right now.
         * Just abort. The caller will repoll after a while.
         */
        if (!(val & AC_ELDD_ELD_VALID)) {
            snd_printd(KERN_INFO
                  "HDMI: invalid ELD data byte %d\n", i);
            ret = -EINVAL;
            goto error;
        }
        val &= AC_ELDD_ELD_DATA;
        /*
         * The first byte cannot be zero. This can happen on some DVI
         * connections. Some Intel chips may also need some 250ms delay
         * to return non-zero ELD data, even when the graphics driver
         * correctly writes ELD content before setting ELD_valid bit.
         */
        if (!val && !i) {
            snd_printdd(KERN_INFO "HDMI: 0 ELD data\n");
            ret = -EINVAL;
            goto error;
        }
        buf[i] = val;
    }

    ret = hdmi_update_eld(eld, buf, size);

error:
    return ret;
}

static void hdmi_print_pcm_rates(int pcm, char *buf, int buflen)
{
    static unsigned int alsa_rates[] = {
        5512, 8000, 11025, 16000, 22050, 32000, 44100, 48000, 64000,
        88200, 96000, 176400, 192000, 384000
    };
    int i, j;

    for (i = 0, j = 0; i < ARRAY_SIZE(alsa_rates); i++)
        if (pcm & (1 << i))
            j += snprintf(buf + j, buflen - j,  " %d",
                alsa_rates[i]);

    buf[j] = '\0'; /* necessary when j == 0 */
}

#define SND_PRINT_RATES_ADVISED_BUFSIZE 80

static void hdmi_show_short_audio_desc(struct cea_sad *a)
{
    char buf[SND_PRINT_RATES_ADVISED_BUFSIZE];
    char buf2[8 + SND_PRINT_BITS_ADVISED_BUFSIZE] = ", bits =";

    if (!a->format)
        return;

    hdmi_print_pcm_rates(a->rates, buf, sizeof(buf));

    if (a->format == AUDIO_CODING_TYPE_LPCM)
        snd_print_pcm_bits(a->sample_bits, buf2 + 8, sizeof(buf2) - 8);
    else if (a->max_bitrate)
        snprintf(buf2, sizeof(buf2),
                ", max bitrate = %d", a->max_bitrate);
    else
        buf2[0] = '\0';

    _snd_printd(SND_PR_VERBOSE, "HDMI: supports coding type %s:"
            " channels = %d, rates =%s%s\n",
            cea_audio_coding_type_names[a->format],
            a->channels,
            buf,
            buf2);
}

void snd_print_channel_allocation(int spk_alloc, char *buf, int buflen)
{
    int i, j;

    for (i = 0, j = 0; i < ARRAY_SIZE(cea_speaker_allocation_names); i++) {
        if (spk_alloc & (1 << i))
            j += snprintf(buf + j, buflen - j,  " %s",
                    cea_speaker_allocation_names[i]);
    }
    buf[j] = '\0';  /* necessary when j == 0 */
}

void snd_hdmi_show_eld(struct hdmi_eld *e)
{
    int i;

    _snd_printd(SND_PR_VERBOSE, "HDMI: detected monitor %s at connection type %s\n",
            e->monitor_name,
            eld_connection_type_names[e->conn_type]);

    if (e->spk_alloc) {
        char buf[SND_PRINT_CHANNEL_ALLOCATION_ADVISED_BUFSIZE];
        snd_print_channel_allocation(e->spk_alloc, buf, sizeof(buf));
        _snd_printd(SND_PR_VERBOSE, "HDMI: available speakers:%s\n", buf);
    }

    for (i = 0; i < e->sad_count; i++)
        hdmi_show_short_audio_desc(e->sad + i);
}

#ifdef CONFIG_PROC_FS

static void hdmi_print_sad_info(int i, struct cea_sad *a,
                struct snd_info_buffer *buffer)
{
    char buf[SND_PRINT_RATES_ADVISED_BUFSIZE];

    snd_iprintf(buffer, "sad%d_coding_type\t[0x%x] %s\n",
            i, a->format, cea_audio_coding_type_names[a->format]);
    snd_iprintf(buffer, "sad%d_channels\t\t%d\n", i, a->channels);

    hdmi_print_pcm_rates(a->rates, buf, sizeof(buf));
    snd_iprintf(buffer, "sad%d_rates\t\t[0x%x]%s\n", i, a->rates, buf);

    if (a->format == AUDIO_CODING_TYPE_LPCM) {
        snd_print_pcm_bits(a->sample_bits, buf, sizeof(buf));
        snd_iprintf(buffer, "sad%d_bits\t\t[0x%x]%s\n",
                            i, a->sample_bits, buf);
    }

    if (a->max_bitrate)
        snd_iprintf(buffer, "sad%d_max_bitrate\t%d\n",
                            i, a->max_bitrate);

    if (a->profile)
        snd_iprintf(buffer, "sad%d_profile\t\t%d\n", i, a->profile);
}

static void hdmi_print_eld_info(struct snd_info_entry *entry,
                struct snd_info_buffer *buffer)
{
    struct hdmi_eld *e = entry->private_data;
    char buf[SND_PRINT_CHANNEL_ALLOCATION_ADVISED_BUFSIZE];
    int i;
    static char *eld_versoin_names[32] = {
        "reserved",
        "reserved",
        "CEA-861D or below",
        [3 ... 30] = "reserved",
        [31] = "partial"
    };
    static char *cea_edid_version_names[8] = {
        "no CEA EDID Timing Extension block present",
        "CEA-861",
        "CEA-861-A",
        "CEA-861-B, C or D",
        [4 ... 7] = "reserved"
    };

    snd_iprintf(buffer, "monitor_present\t\t%d\n", e->monitor_present);
    snd_iprintf(buffer, "eld_valid\t\t%d\n", e->eld_valid);
    if (!e->eld_valid)
        return;
    snd_iprintf(buffer, "monitor_name\t\t%s\n", e->monitor_name);
    snd_iprintf(buffer, "connection_type\t\t%s\n",
                eld_connection_type_names[e->conn_type]);
    snd_iprintf(buffer, "eld_version\t\t[0x%x] %s\n", e->eld_ver,
                    eld_versoin_names[e->eld_ver]);
    snd_iprintf(buffer, "edid_version\t\t[0x%x] %s\n", e->cea_edid_ver,
                cea_edid_version_names[e->cea_edid_ver]);
    snd_iprintf(buffer, "manufacture_id\t\t0x%x\n", e->manufacture_id);
    snd_iprintf(buffer, "product_id\t\t0x%x\n", e->product_id);
    snd_iprintf(buffer, "port_id\t\t\t0x%llx\n", (long long)e->port_id);
    snd_iprintf(buffer, "support_hdcp\t\t%d\n", e->support_hdcp);
    snd_iprintf(buffer, "support_ai\t\t%d\n", e->support_ai);
    snd_iprintf(buffer, "audio_sync_delay\t%d\n", e->aud_synch_delay);

    snd_print_channel_allocation(e->spk_alloc, buf, sizeof(buf));
    snd_iprintf(buffer, "speakers\t\t[0x%x]%s\n", e->spk_alloc, buf);

    snd_iprintf(buffer, "sad_count\t\t%d\n", e->sad_count);

    for (i = 0; i < e->sad_count; i++)
        hdmi_print_sad_info(i, e->sad + i, buffer);
}

static void hdmi_write_eld_info(struct snd_info_entry *entry,
                struct snd_info_buffer *buffer)
{
    struct hdmi_eld *e = entry->private_data;
    char line[64];
    char name[64];
    char *sname;
    long long val;
    unsigned int n;

    while (!snd_info_get_line(buffer, line, sizeof(line))) {
        if (sscanf(line, "%s %llx", name, &val) != 2)
            continue;
        /*
         * We don't allow modification to these fields:
         *  monitor_name manufacture_id product_id
         *  eld_version edid_version
         */
        if (!strcmp(name, "monitor_present"))
            e->monitor_present = val;
        else if (!strcmp(name, "eld_valid"))
            e->eld_valid = val;
        else if (!strcmp(name, "connection_type"))
            e->conn_type = val;
        else if (!strcmp(name, "port_id"))
            e->port_id = val;
        else if (!strcmp(name, "support_hdcp"))
            e->support_hdcp = val;
        else if (!strcmp(name, "support_ai"))
            e->support_ai = val;
        else if (!strcmp(name, "audio_sync_delay"))
            e->aud_synch_delay = val;
        else if (!strcmp(name, "speakers"))
            e->spk_alloc = val;
        else if (!strcmp(name, "sad_count"))
            e->sad_count = val;
        else if (!strncmp(name, "sad", 3)) {
            sname = name + 4;
            n = name[3] - '0';
            if (name[4] >= '0' && name[4] <= '9') {
                sname++;
                n = 10 * n + name[4] - '0';
            }
            if (n >= ELD_MAX_SAD)
                continue;
            if (!strcmp(sname, "_coding_type"))
                e->sad[n].format = val;
            else if (!strcmp(sname, "_channels"))
                e->sad[n].channels = val;
            else if (!strcmp(sname, "_rates"))
                e->sad[n].rates = val;
            else if (!strcmp(sname, "_bits"))
                e->sad[n].sample_bits = val;
            else if (!strcmp(sname, "_max_bitrate"))
                e->sad[n].max_bitrate = val;
            else if (!strcmp(sname, "_profile"))
                e->sad[n].profile = val;
            if (n >= e->sad_count)
                e->sad_count = n + 1;
        }
    }
}


int snd_hda_eld_proc_new(struct hda_codec *codec, struct hdmi_eld *eld,
             int index)
{
    char name[32];
    struct snd_info_entry *entry;
    int err;

    snprintf(name, sizeof(name), "eld#%d.%d", codec->addr, index);
    err = snd_card_proc_new(codec->bus->card, name, &entry);
    if (err < 0)
        return err;

    snd_info_set_text_ops(entry, eld, hdmi_print_eld_info);
    entry->c.text.write = hdmi_write_eld_info;
    entry->mode |= S_IWUSR;
    eld->proc_entry = entry;

    return 0;
}

void snd_hda_eld_proc_free(struct hda_codec *codec, struct hdmi_eld *eld)
{
    if (!codec->bus->shutdown && eld->proc_entry) {
        snd_device_free(codec->bus->card, eld->proc_entry);
        eld->proc_entry = NULL;
    }
}

#endif /* CONFIG_PROC_FS */

/* update PCM info based on ELD */
void snd_hdmi_eld_update_pcm_info(struct hdmi_eld *eld,
                  struct hda_pcm_stream *hinfo)
{
    u32 rates;
    u64 formats;
    unsigned int maxbps;
    unsigned int channels_max;
    int i;

    /* assume basic audio support (the basic audio flag is not in ELD;
     * however, all audio capable sinks are required to support basic
     * audio) */
    rates = SNDRV_PCM_RATE_32000 | SNDRV_PCM_RATE_44100 |
        SNDRV_PCM_RATE_48000;
    formats = SNDRV_PCM_FMTBIT_S16_LE;
    maxbps = 16;
    channels_max = 2;
    for (i = 0; i < eld->sad_count; i++) {
        struct cea_sad *a = &eld->sad[i];
        rates |= a->rates;
        if (a->channels > channels_max)
            channels_max = a->channels;
        if (a->format == AUDIO_CODING_TYPE_LPCM) {
            if (a->sample_bits & AC_SUPPCM_BITS_20) {
                formats |= SNDRV_PCM_FMTBIT_S32_LE;
                if (maxbps < 20)
                    maxbps = 20;
            }
            if (a->sample_bits & AC_SUPPCM_BITS_24) {
                formats |= SNDRV_PCM_FMTBIT_S32_LE;
                if (maxbps < 24)
                    maxbps = 24;
            }
        }
    }

    /* restrict the parameters by the values the codec provides */
    hinfo->rates &= rates;
    hinfo->formats &= formats;
    hinfo->maxbps = min(hinfo->maxbps, maxbps);
    hinfo->channels_max = min(hinfo->channels_max, channels_max);
}