Hi,
On Dec 13 2016 06:36, Takashi Iwai wrote:
On Sun, 11 Dec 2016 12:31:38 +0100, Takashi Sakamoto wrote:
In a design of ALSA PCM interface, for PCM frame transmission to/from kernel space, applications can select from two options; direct memory access or ioctl(2). Available options are decided depending on device capacity and machine architecture. Applications can get available options by the first entry of 'struct snd_pcm_hw_params.masks'.
When the mask includes 'SNDRV_PCM_ACCESS_MMAP_xxx', applications can use direct memory access. For this use case, userspace library has two types of PCM API. One is to expose a pointer over the memory to start reading/writing PCM frames. Another is to copy PCM frames between the memory and a given buffer.
Current documentation includes wrong references to these APIs to describe their advantages/disadvantages. This confuses application developers because the references indicate PCM APIs to execute ioctl(2) operation to read/write PCM frames.
This commit fixes the bug.
Signed-off-by: Takashi Sakamoto o-takashi@sakamocchi.jp
Applied, thanks.
Thanks.
Additionally, I'm pleased if you apply below patches to fix some compiler warnings which topology features recently got. I guess Intel developers are under their holidays.
[alsa-devel] [PATCH][alsa-lib] topology: fix sign-compare warning introduced to set_link_hw_config() and tplg_add_link_object() http://mailman.alsa-project.org/pipermail/alsa-devel/2016-November/115245.ht...
[alsa-devel] [PATCH][alsa-lib] topology: fix unused-variable warnings introduced to build_link() http://mailman.alsa-project.org/pipermail/alsa-devel/2016-November/115246.ht...
[alsa-devel] [PATCH][alsa-lib] topology: fix unused-const-variable warning http://mailman.alsa-project.org/pipermail/alsa-devel/2016-November/115247.ht...
Regards
Takashi Sakamoto