[ALSA] pcm-oss - Add bugg-yptr option

Documentation,ALSA<-OSS emulation
Added 'buggy-ptr' proc option to switch the behavior of GETOPTR ioctl.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

3 files changed, 11 insertions, 2 deletions

diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index a7fc75f53bbe..57e82a5fae71 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -1592,6 +1592,8 @@ Proc interfaces (/proc/asound)
           - whole-frag  write only whole fragments (optimization affecting
                         playback only)
           - no-silence  do not fill silence ahead to avoid clicks
+          - buggy-ptr   Returns the whitespace blocks in GETOPTR ioctl
+                        instead of filled blocks
 
   Example: echo "x11amp 128 16384" > /proc/asound/card0/pcm0p/oss
            echo "squake 0 0 disable" > /proc/asound/card0/pcm0c/oss
diff --git a/include/sound/pcm_oss.h b/include/sound/pcm_oss.h
index 518728536bc6..0b67c9d105af 100644
--- a/include/sound/pcm_oss.h
+++ b/include/sound/pcm_oss.h
@@ -32,7 +32,8 @@ struct _snd_pcm_oss_setup {
                      block:1,
                      nonblock:1,
                      partialfrag:1,
-                     nosilence:1;
+                     nosilence:1,
+                     buggyptr:1;
         unsigned int periods;
         unsigned int period_size;
         snd_pcm_oss_setup_t *next;
diff --git a/sound/core/oss/pcm_oss.c b/sound/core/oss/pcm_oss.c
index 1e606399d74a..a038fd8a53f3 100644
--- a/sound/core/oss/pcm_oss.c
+++ b/sound/core/oss/pcm_oss.c
@@ -1543,7 +1543,11 @@ static int snd_pcm_oss_get_ptr(snd_pcm_oss_file_t *pcm_oss_file, int stream, str
         } else {
                 delay = snd_pcm_oss_bytes(substream, delay);
                 if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
-                        info.blocks = (runtime->oss.buffer_bytes - delay - fixup) / runtime->oss.period_bytes;
+                        snd_pcm_oss_setup_t *setup = substream->oss.setup;
+                        if (setup && setup->buggyptr)
+                                info.blocks = (runtime->oss.buffer_bytes - delay - fixup) / runtime->oss.period_bytes;
+                        else
+                                info.blocks = (delay + fixup) / runtime->oss.period_bytes;
                         info.bytes = (runtime->oss.bytes - delay) & INT_MAX;
                 } else {
                         delay += fixup;
@@ -2350,6 +2354,8 @@ static void snd_pcm_oss_proc_write(snd_info_entry_t *entry,
                                 template.partialfrag = 1;
                         } else if (!strcmp(str, "no-silence")) {
                                 template.nosilence = 1;
+                        } else if (!strcmp(str, "buggy-ptr")) {
+                                template.buggyptr = 1;
                         }
                 } while (*str);
                 if (setup == NULL) {