In ALSA control interface, each element set can have threshold level
information. This information is transferred between drivers/applications,
in a shape of tlv packet. The layout of this packet is defined in
'uapi/sound/asound.h' (struct snd_ctl_tlv):
struct snd_ctl_tlv {
unsigned int numid;
unsigned int length;
unsigned int tlv[0];
};
Data in the payload (struct snd_ctl_tlv.tlv) is expected to be filled
according to our own protocol. This protocol is described in
'include/sound/tlv.h'. A layout of the payload is expected as:
struct snd_ctl_tlv.tlv[0]: one of SNDRV_CTL_TLVT_XXX
struct snd_ctl_tlv.tlv[1]: Length of data
struct snd_ctl_tlv.tlv[2...]: data
Unfortunately, the macro is not exported to user land yet, thus
applications cannot get to know the protocol.
Additionally, ALSA control core has a feature called as 'user-defined'
element set. This allows applications to add/remove arbitrary element sets
with elements to control devices. Elements in the element set can be
operated by the same way as the ones added by in-kernel implementation.
For threshold level information of 'user-defined' element set, applications
need to register the information to an element set. However, as described
above, layout of the payload is closed in kernel land. This is quite
inconvenient, too.
This commit moves the protocol to UAPI header for TLV.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Make sure userspace can define TLV controls for topology using the correct
type numbers and channel mappings.
Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Userspace is not meant to have to handle all strange dB ranges,
so add a specification comment.
Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This patch implements the basic data types for the standard channel
mapping API handling.
- The definitions of the channel positions and the new TLV types are
added in sound/asound.h and sound/tlv.h, so that they can be
referred from user-space.
- Introduced a new helper function snd_pcm_add_chmap_ctls() to create
control elements representing the channel maps for each PCM
(sub)stream.
- Some standard pre-defined channel maps are provided for
convenience.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Add a DECLARE_TLV_DB_RANGE() macro so that dB range information
can be specified without having to count the items manually for
TLV_DB_RANGE_HEAD().
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Add the DECLARE_TLV_CONTAINER() macro to allow having static
TLVs containing more than one item.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Add helper macros with a little bit of preprocessor magic to
automatically compute the length of a TLV item. This lets us avoid
having to compute this by hand, and will allow to use items that do
not use a fixed length.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Add new types for TLV dB scale specified with min/max values instead
of min/step since the resolution can't match always with the one
a device provides. For example, usb audio devices give 1/256 dB
resolution while ALSA TLV is based on 1/100 dB resolution.
The new min/max types have less problems because the possible
rounding error happens only at min/max.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Added the definition of TLV dB range compound. It contains one or
more dB-range or linear-volume TLV entries with min/max ranges.
Used for volume controls with non-linear curves.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>
Added the definition of linear volume TLV type.
Some DSP chips and codecs (e.g. AK codec) use linear volume control.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>
This patch implements a TLV mechanism to transfer an additional information
like dB scale to the user space. The types might be extended in future.
Acked-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>
