On Tue, Jul 15, 2014 at 04:36:21PM +0200, Takashi Iwai wrote:
At Tue, 15 Jul 2014 12:17:45 +0530, Vinod Koul wrote:
From: Omair Mohammed Abdullah omair.m.abdullah@intel.com
ALSA supports arbitrary length TLVs for each kcontrol that can be used to pass metadata about the control (e.g. volumes, enum information). The same transport mechanism is now used for arbitrary length data by defining a new helper.
Signed-off-by: Omair Mohammed Abdullah omair.m.abdullah@intel.com Signed-off-by: Vinod Koul vinod.koul@intel.com
As discussed in [1] we are adding a new approach to solve the byte control extensions by using existing TLVs and combining them with byte controls. The usermode on seeing byte control + TLV can treat it differently as it does for control + TLV combination today. This way we don't change kernel API and existing users will be happy, while providing embedded folks facility to pass large bytes data to kcontrols [1]: http://mailman.alsa-project.org/pipermail/alsa-devel/2013-November/069483.ht...
Yeah, this would bypass the limitation nicely.
Yes thats what I realized when Omair pointed this out!
+int snd_soc_bytes_tlv_callback(struct snd_kcontrol *kcontrol, int op_flag,
unsigned int size, unsigned int __user *tlv)+{
- struct soc_bytes_ext *params = (void *)kcontrol->private_value;
- unsigned int count = size < params->max ? size : params->max;
- switch (op_flag) {
- case 0:
if (params->get)params->get(tlv, count);break;- case 1:
if (params->put)params->put(tlv, count);break;No error propagation from the callback? Also, if a driver doesn't provide get or put, it gets no error?
Will fix that
BTW, about the value of op_flag: I have a patch to define the constants (attached below), which I forgot until now. Now I put it into topic/tlv-opflag branch of sound git tree. If you'd like to use the new constants, merge (or base on) this branch.
yes rebased now..