1 files changed, 74 insertions, 18 deletions

diff --git a/sound/usb/format.c b/sound/usb/format.c
index 8eccf17a4ac6..30364aba79cc 100644
--- a/sound/usb/format.c
+++ b/sound/usb/format.c
@@ -206,6 +206,60 @@ static int parse_audio_format_rates_v1(struct snd_usb_audio *chip, struct audiof
 }
 
 /*
+ * Helper function to walk the array of sample rate triplets reported by
+ * the device. The problem is that we need to parse whole array first to
+ * get to know how many sample rates we have to expect.
+ * Then fp->rate_table can be allocated and filled.
+ */
+static int parse_uac2_sample_rate_range(struct audioformat *fp, int nr_triplets,
+                                        const unsigned char *data)
+{
+        int i, nr_rates = 0;
+
+        fp->rates = fp->rate_min = fp->rate_max = 0;
+
+        for (i = 0; i < nr_triplets; i++) {
+                int min = combine_quad(&data[2 + 12 * i]);
+                int max = combine_quad(&data[6 + 12 * i]);
+                int res = combine_quad(&data[10 + 12 * i]);
+                int rate;
+
+                if ((max < 0) || (min < 0) || (res < 0) || (max < min))
+                        continue;
+
+                /*
+                 * for ranges with res == 1, we announce a continuous sample
+                 * rate range, and this function should return 0 for no further
+                 * parsing.
+                 */
+                if (res == 1) {
+                        fp->rate_min = min;
+                        fp->rate_max = max;
+                        fp->rates = SNDRV_PCM_RATE_CONTINUOUS;
+                        return 0;
+                }
+
+                for (rate = min; rate <= max; rate += res) {
+                        if (fp->rate_table)
+                                fp->rate_table[nr_rates] = rate;
+                        if (!fp->rate_min || rate < fp->rate_min)
+                                fp->rate_min = rate;
+                        if (!fp->rate_max || rate > fp->rate_max)
+                                fp->rate_max = rate;
+                        fp->rates |= snd_pcm_rate_to_rate_bit(rate);
+
+                        nr_rates++;
+
+                        /* avoid endless loop */
+                        if (res == 0)
+                                break;
+                }
+        }
+
+        return nr_rates;
+}
+
+/*
  * parse the format descriptor and stores the possible sample rates
  * on the audioformat table (audio class v2).
  */
@@ -215,7 +269,7 @@ static int parse_audio_format_rates_v2(struct snd_usb_audio *chip,
 {
         struct usb_device *dev = chip->dev;
         unsigned char tmp[2], *data;
-        int i, nr_rates, data_size, ret = 0;
+        int nr_triplets, data_size, ret = 0;
         int clock = snd_usb_clock_find_source(chip, chip->ctrl_intf, fp->clock);
 
         if (clock < 0) {
@@ -237,8 +291,8 @@ static int parse_audio_format_rates_v2(struct snd_usb_audio *chip,
                 goto err;
         }
 
-        nr_rates = (tmp[1] << 8) | tmp[0];
-        data_size = 2 + 12 * nr_rates;
+        nr_triplets = (tmp[1] << 8) | tmp[0];
+        data_size = 2 + 12 * nr_triplets;
         data = kzalloc(data_size, GFP_KERNEL);
         if (!data) {
                 ret = -ENOMEM;
@@ -259,26 +313,28 @@ static int parse_audio_format_rates_v2(struct snd_usb_audio *chip,
                 goto err_free;
         }
 
-        fp->rate_table = kmalloc(sizeof(int) * nr_rates, GFP_KERNEL);
+        /* Call the triplet parser, and make sure fp->rate_table is NULL.
+         * We just use the return value to know how many sample rates we
+         * will have to deal with. */
+        kfree(fp->rate_table);
+        fp->rate_table = NULL;
+        fp->nr_rates = parse_uac2_sample_rate_range(fp, nr_triplets, data);
+
+        if (fp->nr_rates == 0) {
+                /* SNDRV_PCM_RATE_CONTINUOUS */
+                ret = 0;
+                goto err_free;
+        }
+
+        fp->rate_table = kmalloc(sizeof(int) * fp->nr_rates, GFP_KERNEL);
         if (!fp->rate_table) {
                 ret = -ENOMEM;
                 goto err_free;
         }
 
-        fp->nr_rates = 0;
-        fp->rate_min = fp->rate_max = 0;
-
-        for (i = 0; i < nr_rates; i++) {
-                int rate = combine_quad(&data[2 + 12 * i]);
-
-                fp->rate_table[fp->nr_rates] = rate;
-                if (!fp->rate_min || rate < fp->rate_min)
-                        fp->rate_min = rate;
-                if (!fp->rate_max || rate > fp->rate_max)
-                        fp->rate_max = rate;
-                fp->rates |= snd_pcm_rate_to_rate_bit(rate);
-                fp->nr_rates++;
-        }
+        /* Call the triplet parser again, but this time, fp->rate_table is
+         * allocated, so the rates will be stored */
+        parse_uac2_sample_rate_range(fp, nr_triplets, data);
 
 err_free:
         kfree(data);