Commit f6161f37 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: docs: Update document about the default PCM ioctl ops 

Mention that it's completely optional now.

Link: https://lore.kernel.org/r/20191117085308.23915-5-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent fc033cbf

Documentation/sound/kernel-api/writing-an-alsa-driver.rst

+4 −4
Original line number Diff line number Diff line
@@ -1341,7 +1341,6 @@ shows only the skeleton, how to build up the PCM interfaces. 
      static struct snd_pcm_ops snd_mychip_playback_ops = {

              .open =        snd_mychip_playback_open,

              .close =       snd_mychip_playback_close,

              .ioctl =       snd_pcm_lib_ioctl,

              .hw_params =   snd_mychip_pcm_hw_params,

              .hw_free =     snd_mychip_pcm_hw_free,

              .prepare =     snd_mychip_pcm_prepare,
@@ -1353,7 +1352,6 @@ shows only the skeleton, how to build up the PCM interfaces. 
      static struct snd_pcm_ops snd_mychip_capture_ops = {

              .open =        snd_mychip_capture_open,

              .close =       snd_mychip_capture_close,

              .ioctl =       snd_pcm_lib_ioctl,

              .hw_params =   snd_mychip_pcm_hw_params,

              .hw_free =     snd_mychip_pcm_hw_free,

              .prepare =     snd_mychip_pcm_prepare,
@@ -1456,7 +1454,6 @@ The operators are defined typically like this: 
  static struct snd_pcm_ops snd_mychip_playback_ops = {

          .open =        snd_mychip_pcm_open,

          .close =       snd_mychip_pcm_close,

          .ioctl =       snd_pcm_lib_ioctl,

          .hw_params =   snd_mychip_pcm_hw_params,

          .hw_free =     snd_mychip_pcm_hw_free,

          .prepare =     snd_mychip_pcm_prepare,
@@ -1913,7 +1910,10 @@ ioctl callback 
~~~~~~~~~~~~~~



This is used for any special call to pcm ioctls. But usually you can

pass a generic ioctl callback, :c:func:`snd_pcm_lib_ioctl()`.

leave it as NULL, then PCM core calls the generic ioctl callback

function :c:func:`snd_pcm_lib_ioctl()`.  If you need to deal with the

unique setup of channel info or reset procedure, you can pass your own

callback function here.



hw_params callback

~~~~~~~~~~~~~~~~~~~