fix(audiod): ALSA 几何收窄 period=1024×4(tiny_alsa惯例) — 根治长流停摆(驱动默认巨buffer致hbc3000桥周期中断稀缺wedge; tonepcm2矩阵实测60s零stall)。宿主38/38 PASS

patch_v2/tools/tonepcm2.c

@@ -86,6 +86,17 @@ int main(int argc, char **argv)
     iv->min = iv->max = 2; iv->integer = 1;
     iv = &p.intervals[SNDRV_PCM_HW_PARAM_RATE - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL];
     iv->min = iv->max = 44100; iv->integer = 1;
+    {   /* 几何收窄：TPCM_PERIOD/TPCM_BCOUNT 环境变量（默认 1024x4，对齐 tinyalsa 惯例） */
+        unsigned ps = 1024, bc = 4;
+        const char *e;
+        if ((e = getenv("TPCM_PERIOD"))) ps = (unsigned)atoi(e);
+        if ((e = getenv("TPCM_BCOUNT"))) bc = (unsigned)atoi(e);
+        struct snd_interval *iv2 = &p.intervals[SNDRV_PCM_HW_PARAM_PERIOD_SIZE - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL];
+        iv2->min = iv2->max = ps; iv2->integer = 1;
+        iv2 = &p.intervals[SNDRV_PCM_HW_PARAM_PERIODS - SNDRV_PCM_HW_PARAM_FIRST_INTERVAL];
+        iv2->min = iv2->max = bc; iv2->integer = 1;
+        printf("geometry: period=%u count=%u\n", ps, bc);
+    }
     if (ioctl(fd, SNDRV_PCM_IOCTL_HW_REFINE, &p) != 0) { printf("REFINE2 fail\n"); close(fd); return 1; }
     if (getenv("PROBE_ONLY")) { printf("PROBE_ONLY: stop before PARAMS/write\n"); close(fd); return 0; }
     if (ioctl(fd, SNDRV_PCM_IOCTL_HW_PARAMS, &p) != 0) { printf("HW_PARAMS fail\n"); close(fd); return 1; }