[RK3288][Android6.0] Audio中的HW Params设置流程

来源：互联网发布：js移除onclick 编辑：程序博客网时间：2024/06/06 16:39

Platform: Rockchip
OS: Android 6.0
Kernel: 3.10.92

这部分内容比较繁琐,,先从初始化开始了解里面参数意义,以period size

这个参数为线索来追终代码流程.

pcm_native.c
snd_pcm_hw_constraints_init():

int snd_pcm_hw_constraints_init(struct snd_pcm_substream *substream){    struct snd_pcm_runtime *runtime = substream->runtime;    //ASOC对应hw params有参数大小限制,一定要在它的范围内,否则设置无效.    //相关信息都保存在hw_constraints中.    struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;    int k, err;......    //每个hw参数规则都会被添加进去来作追踪.    err = snd_pcm_hw_rule_add(runtime, 0, SNDRV_PCM_HW_PARAM_PERIOD_SIZE,                  snd_pcm_hw_rule_mulkdiv, (void*) 8,                  SNDRV_PCM_HW_PARAM_PERIOD_BYTES, SNDRV_PCM_HW_PARAM_FRAME_BITS, -1);......}

struct snd_pcm_hw_constraints {    //mask用来表示后面的intervals是否能访问,没有设置是不行的.    struct snd_mask masks[SNDRV_PCM_HW_PARAM_LAST_MASK -             SNDRV_PCM_HW_PARAM_FIRST_MASK + 1];    //保存所有hw param值.    struct snd_interval intervals[SNDRV_PCM_HW_PARAM_LAST_INTERVAL -                 SNDRV_PCM_HW_PARAM_FIRST_INTERVAL + 1];    //目前已有规则总数    unsigned int rules_num;    //存规则势必要分配空间,当rules_num达到rules_all的时候,    //会每次分配16个存储空间,而不是一次分配一个,这样可以提高效率,    //因此rules_all总是>=rules_num.    unsigned int rules_all;    //所有规则用此结构表示.    struct snd_pcm_hw_rule *rules;};

snd_pcm_hw_rule_add():

int snd_pcm_hw_rule_add(struct snd_pcm_runtime *runtime, unsigned int cond,            int var,            snd_pcm_hw_rule_func_t func, void *private,            int dep, ...){    struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;    struct snd_pcm_hw_rule *c;......    //每添加一个interval,constrs->rules_num就会随着增加,    //当超过constrs->rules_all,就需要分配新空间用于存储interval.    if (constrs->rules_num >= constrs->rules_all) {        struct snd_pcm_hw_rule *new;        //基于效率,每次直接分配16个.        unsigned int new_rules = constrs->rules_all + 16;        //分配的结构是struct snd_pcm_hw_rule        new = kcalloc(new_rules, sizeof(*c), GFP_KERNEL);......    }    //填充rules,下面的值会以snd_pcm_hw_constraints_init()调用中的实际值为例.    c = &constrs->rules[constrs->rules_num];    //为0    c->cond = cond;    //后面会回调snd_pcm_hw_rule_mulkdiv()来计算period size.    c->func = func;    //SNDRV_PCM_HW_PARAM_PERIOD_SIZE    c->var = var;    //为8,后面计算period size会当系数用.    c->private = private;    k = 0;    while (1) {......    //SNDRV_PCM_HW_PARAM_PERIOD_BYTES和SNDRV_PCM_HW_PARAM_FRAME_BITS    //存到deps数组中,后面通过这两个来重计算period size.        c->deps[k++] = dep;.....    constrs->rules_num++;......}

有些参数如period count, channel等,一开始它的值会根据硬件限制定好大范围了,如rk_pcm.c

static const struct snd_pcm_hardware rockchip_pcm_hardware = {    .info            = SNDRV_PCM_INFO_INTERLEAVED |                    SNDRV_PCM_INFO_BLOCK_TRANSFER |                    SNDRV_PCM_INFO_MMAP |                    SNDRV_PCM_INFO_MMAP_VALID |                    SNDRV_PCM_INFO_PAUSE |                    SNDRV_PCM_INFO_RESUME,    .formats        =   SNDRV_PCM_FMTBIT_S24_LE |                    SNDRV_PCM_FMTBIT_S20_3LE |                    SNDRV_PCM_FMTBIT_S16_LE,    //最少双通道,最大八通道.    .channels_min        = 2,    .channels_max        = 8,    .buffer_bytes_max    = 2*1024*1024,/*128*1024,*/    .period_bytes_min    = 64,    .period_bytes_max    = 512*1024,/*32*1024,//2048*4,///PAGE_SIZE*2,*/    .periods_min        = 3,    .periods_max        = 128,    .fifo_size        = 16,};

然后会被保存到hw interval中:

int snd_pcm_hw_constraints_complete(struct snd_pcm_substream *substream){......    err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_RATE,                       hw->rate_min, hw->rate_max);......}

int snd_pcm_hw_constraint_minmax(struct snd_pcm_runtime *runtime, snd_pcm_hw_param_t var,                 unsigned int min, unsigned int max){    struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;    struct snd_interval t;    t.min = min;    t.max = max;    t.openmin = t.openmax = 0;    t.integer = 0;    //新的配置更新到旧的interval中.    return snd_interval_refine(constrs_interval(constrs, var), &t);}

这样默认就有个范围值了,这样,当用户空间设置时,就不能超过这个硬件设置范围,否则就会出错了!

用户空间对period size的配置:

struct pcm_config pcm_config_in = {    .channels = 2,    .rate = 44100,    .period_size = 16,    .period_count = 32,    .format = PCM_FORMAT_S16_LE,};

然后会被传到pcm_open()中

struct pcm *pcm_open(unsigned int card, unsigned int device,                     unsigned int flags, struct pcm_config *config){......    //config->period_size被传到了这里.    //函数用来设置period size的最小值    //然后会通过下面的ioctl传给kernel看是否超出范围了.    param_set_min(¶ms, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, config->period_size);......    if (ioctl(pcm->fd, SNDRV_PCM_IOCTL_HW_PARAMS, ¶ms)) {        oops(pcm, errno, "cannot set hw params");        goto fail_close;    }    //返回设置可以设置的值.    config->period_size = param_get_int(¶ms, SNDRV_PCM_HW_PARAM_PERIOD_SIZE);......}

param_set_min():

static void param_set_int(struct snd_pcm_hw_params *p, int n, unsigned int val){    //判断当前SNDRV_PCM_HW_PARAM_PERIOD_SIZE是否在interval列表范围内,肯定成立.    if (param_is_interval(n)) {        //取出对应的interval        struct snd_interval *i = param_to_interval(p, n);        //赋值最大最小都是config->period_size        i->min = val;        i->max = val;        i->integer = 1;    }}

看ioctl进入kernel
ioctl ->
   snd_pcm_common_ioctl1 ->
       snd_pcm_hw_params_user ->
           snd_pcm_hw_params ->
               snd_pcm_hw_refine   //参数处理都在这里完成
snd_pcm_hw_refine():

int snd_pcm_hw_refine(struct snd_pcm_substream *substream,              struct snd_pcm_hw_params *params){    unsigned int k;    struct snd_pcm_hardware *hw;    struct snd_interval *i = NULL;    struct snd_mask *m = NULL;    struct snd_pcm_hw_constraints *constrs = &substream->runtime->hw_constraints;    unsigned int rstamps[constrs->rules_num];    unsigned int vstamps[SNDRV_PCM_HW_PARAM_LAST_INTERVAL + 1];......    //先对mask做处理,这里不太明白mask和后面提到的interval有什么联系?    for (k = SNDRV_PCM_HW_PARAM_FIRST_MASK; k <= SNDRV_PCM_HW_PARAM_LAST_MASK; k++) {        //取出对应的mask        m = hw_param_mask(params, k);        //每个mask使用了两个字节总共64位        //如果一个都没设置,那就不处理参数了,当前正常流程不会发生.        if (snd_mask_empty(m))            return -EINVAL;        //rmask用于存每个interval对应的位,如果没设置就不能往下走.        if (!(params->rmask & (1 << k)))            continue;        //调试信息.#ifdef RULES_DEBUG        printk(KERN_DEBUG "%s = ", snd_pcm_hw_param_names[k]);        printk("%04x%04x%04x%04x -> ", m->bits[3], m->bits[2], m->bits[1], m->bits[0]);#endif        //更新旧的mask信息        changed = snd_mask_refine(m, constrs_mask(constrs, k));#ifdef RULES_DEBUG        printk("%04x%04x%04x%04x\n", m->bits[3], m->bits[2], m->bits[1], m->bits[0]);#endif        //如果前后有变化,则标记.        if (changed)            params->cmask |= 1 << k;        if (changed < 0)            return changed;    }    //依次处理每个interval    for (k = SNDRV_PCM_HW_PARAM_FIRST_INTERVAL; k <= SNDRV_PCM_HW_PARAM_LAST_INTERVAL; k++) {        //取出        i = hw_param_interval(params, k);......        //替换旧的interval        changed = snd_interval_refine(i, constrs_interval(constrs, k));......    }......    do {        again = 0;        for (k = 0; k < constrs->rules_num; k++) {            struct snd_pcm_hw_rule *r = &constrs->rules[k];......            //执行之前注册的回调函数,这里是snd_pcm_hw_rule_mulkdiv            changed = r->func(params, r);......        }    } while (again);......}

snd_pcm_hw_rule_mulkdiv():

static int snd_pcm_hw_rule_mulkdiv(struct snd_pcm_hw_params *params,                   struct snd_pcm_hw_rule *rule){    struct snd_interval t;    //参数一对应SNDRV_PCM_HW_PARAM_PERIOD_BYTES的配置    //参数二的是值是8    //参数三对应SNDRV_PCM_HW_PARAM_FRAME_BITS的配置    snd_interval_mulkdiv(hw_param_interval_c(params, rule->deps[0]),             (unsigned long) rule->private,             hw_param_interval_c(params, rule->deps[1]), &t);    //更新配置    return snd_interval_refine(hw_param_interval(params, rule->var), &t);}SNDRV_PCM_HW_PARAM_FRAME_BITS()的设置在snd_pcm_hw_constraints_init()中snd_pcm_hw_constraints_init() {......    snd_interval_setinteger(constrs_interval(constrs, SNDRV_PCM_HW_PARAM_FRAME_BITS));......}

而具体的值是在HAL层设置的:

struct pcm *pcm_open(unsigned int card, unsigned int device,                     unsigned int flags, struct pcm_config *config){......    //对应pcm_config_in的配置,为16*2 = 32.    param_set_int(¶ms, SNDRV_PCM_HW_PARAM_FRAME_BITS,                  pcm_format_to_bits(config->format) * config->channels);......}

而SNDRV_PCM_HW_PARAM_PERIOD_BYTES的值是在

int snd_pcm_hw_constraints_complete(struct snd_pcm_substream *substream){......    //也就是rockchip_pcm_hardware变量中的值.    err = snd_pcm_hw_constraint_minmax(runtime, SNDRV_PCM_HW_PARAM_PERIOD_BYTES,                       hw->period_bytes_min, hw->period_bytes_max);......}

snd_interval_mulkdiv():

void snd_interval_mulkdiv(const struct snd_interval *a, unsigned int k,              const struct snd_interval *b, struct snd_interval *c){......        //c->min = a->min * k / b->max;    c->min = muldiv32(a->min, k, b->max, &r);    c->openmin = (r || a->openmin || b->openmax);    if (b->min > 0) {        c->max = muldiv32(a->max, k, b->min, &r);        if (r) {            c->max++;            c->openmax = 1;        } else            c->openmax = (a->openmax || b->openmin);    } else {        c->max = UINT_MAX;        c->openmax = 0;    }    c->integer = 0;}

参考:
http://blog.csdn.net/u012769691/article/details/46727543
http://blog.chinaunix.net/uid-20564848-id-74213.html
http://blog.csdn.net/crycheng/article/details/7095899

1 0