Hi,
On Jun 27 2017 19:29, Takashi Iwai wrote:
Hi,
this is a revised patchset that is applied on top of the current
for-next branch, in order to optimize the appl_ptr sync on x86-64,
adapting the alsa-lib side change by Sakamoto-san's patchset.
Basically it adds a new ioctl for receiving the supported PCM protocol
version from user-space side, and change the mmap code to allow only
disabling the PCM status record depending on the supported protocol
version. The former patch is identical with the previous version,
only the latter one differs.
The corresponding alsa-lib patch will follow.
thanks,
Takashi
===
Takashi Iwai (2):
ALSA: pcm: Add an ioctl to specify the supported protocol version
ALSA: pcm: Disable only control mmap for explicit appl_ptr sync
include/sound/pcm.h | 1 +
include/uapi/sound/asound.h | 3 ++-
sound/core/pcm_compat.c | 1 +
sound/core/pcm_native.c | 29 ++++++++++++++++++++++++-----
4 files changed, 28 insertions(+), 6 deletions(-)
Reviewed-by: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
I note that the idea of USER_PVERSION ioctl is itself worth for the
other interfaces/protocols such as control. In the interfaces/protocols,
many structures have reserved members. As Iwai-san described in the
first patch, when changing them to utilize these reserved members, this
idea is a solution to balance compatibility and extensibility.
Thanks
Takashi Sakamoto
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