[alsa-devel] [PATCH] alsa-lib: update linked hw_ptr and appl_ptr

[sutar.mounesh at gmail.com]

From: Andreas Pape <apape at de.adit-jv.com>

Plugin file provides no private hw_ptr and appl_ptr but instead links them to the slave pcm.
If the slave pcm itself changes its hw_ptr or app_prt this needs to be done in file plugin, too.
Plugin 'plug' is such a candidate changing the hw_ptr and app_ptr in hw_params call dependent on the automatically inserted plugins.
ALSA unfortunately has no support for automatically updating chained pointers.
A notification on pointer change seems to be prepared inside the snd_pcm_set_ptr() routine via
rbptr->changed(), but it is not (yet) implemented so that we need to care for it manually.

Signed-off-by: Andreas Pape <apape at de.adit-jv.com>
---
 src/pcm/pcm_file.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/pcm/pcm_file.c b/src/pcm/pcm_file.c
index fec76eb..1e3d35b 100644
--- a/src/pcm/pcm_file.c
+++ b/src/pcm/pcm_file.c
@@ -634,6 +634,14 @@ static int snd_pcm_file_hw_params(snd_pcm_t *pcm, snd_pcm_hw_params_t * params)
 			return err;
 		}
 	}
+
+	/* pointer may have changed - e.g if plug is used. */
+	snd_pcm_unlink_hw_ptr(pcm, file->gen.slave);
+	snd_pcm_unlink_appl_ptr(pcm, file->gen.slave);
+
+	snd_pcm_link_hw_ptr(pcm, file->gen.slave);
+	snd_pcm_link_appl_ptr(pcm, file->gen.slave);
+
 	return 0;
 }
 
-- 
1.7.9.5