Isent it the drivers job to make sure that applications do not have to
bother about potentional hardwahere issues,
The ossxmix has the same issues, althought because it happens less
because the updates is a little slower for somereason (havent checked
the code).
But either the driver should protect from to frequent writes, or the
docs should state very clearly that it does not do that and the user of
the library have to rule that in and not write to frequent.
And it's not realy a stupid thing of the application to do, I found
this issue by just making a slider to adjust the volume, and with a
responsive toolkit like Qt this slider will update it's values very fast
when moving the slider knobb.
And that causes alot of writes, and the doc's said nothing about this
being an issue at all so took quite a while before I figured out what
caused the strange behavior.
On Mon, 29 Nov 2010 16:46:45 +0200, Hannu Savolainen
<ha...@opensound.com> wrote:
> Hi,
>
> The logic for preventing too frequent writes belongs to the
> application.
> It is not responsibility of the driver to prevent applications from
> doing stupid things. Sometimes it's necessay and easy but not in this
> case.
>
> Best regards,
>
> Hannu
> ---
> 29.11.2010 16.37, o...@lilltiger.se wrote:
>> It should be realy easy to test on any other card, jusr run a loop
>> that
>> reads the value of an volume mixer and then write this value back
>> to it
>> right away.
>>
>> like:
>> oss_mixer_value vr;
>> vr.dev=extinfo.dev;
>> vr.ctrl=extinfo.ctrl;
>> vr.timestamp=extinfo.timestamp;
>> vr.value=value;
>>
>> while(true)
>> {
>> if( ioctl(device_, SNDCTL_MIX_READ, &vr) == -1 )
>> {
>> }
>> if( ioctl(device_, SNDCTL_MIX_WRITE, &vr) == -1 )
>> {
>> }
>> }
>>
>> If the values dosent go ballistic then it's for sure and hardware
>> issue.
>>
>>
>> But either way, should the backend realy allow for this fast writes
>> of
>> the values as it makes no sense, eats extra io/cpu for no gain at
>> all.
>> In my opinion it should be better if the write function checks if
>> it's
>> the same controler writing, if so keep an storage of that value and
>> allow that value to change for 100ms then write it to the hardware.
>> If another controler writes, then write the stored value, and the
>> value
>> from the new controler. (this is what I did in my GUI to make it
>> work as
>> it should).
>>
>> On Mon, 29 Nov 2010 16:10:26 +0200, Hannu Savolainen
>> <ha...@opensound.com> wrote:
>>> Hi,
>>>
>>> I have never seen this. It's probably a hardware level bug in the
>>> AD1988B codec.
>>>
>>> Best regards,
>>>
>>> Hannu
>>> ----
>>> 29.11.2010 6.54, o...@lilltiger.se wrote:
>>>>
>>>> When calling:
>>>>
>>>> ioctl(device_, SNDCTL_MIX_WRITE, &vr);
>>>>
>>>> to fast the device will act up but not reporting any errors,
>>>> atleast
>>>> when changing the volume.
>>>> The result is that the values written becomes random (often 0,
>>>> but
>>>> seen
>>>> other values as well).
>>>>
>>>> This is realy bad for GUI apps using slider to change the values
>>>> as
>>>> they will spam writes extreamly fast and this will mess upp the
>>>> values.
>>>>
>>>>
>>>> ossinfo:
>>>>
>>>> Version info: OSS 4.2 (b 2002/200911201634) (0x00040100) OSS_HG
>>>> Hg revision: changeset: 874:3c6677155802, tag: tip, date: Sat Nov
>>>> 07
>>>> 10:17:46 2009 +0200, summary: Changed build ID to v4.2-build2002
>>>> Platform: Linux/x86_64 2.6.35-gentoo-r1 #1 SMP Thu Aug 26
>>>> 04:04:44
>>>> CEST
>>>> 2010 (orion)
>>>>
>>>> Number of audio devices: 12
>>>> Number of audio engines: 17
>>>> Number of MIDI devices: 0
>>>> Number of mixer devices: 2
>>>>
>>>>
>>>> Device objects
>>>> 0: osscore0 OSS core services
>>>> 1: oss_hdaudio0 Intel HD Audio interrupts=1132412466
>>>> (1132412466)
>>>> HD Audio controller Intel HD Audio
>>>> Vendor ID 0x8086293e
>>>> Subvendor ID 0x10438277
>>>> Codec 0: AD1988B (0x11d4198b/0x1043829c)
>>>> 2: oss_usb0 USB audio core services
>>>> 3: usb046d08ad-0 USB sound device
>>>> 4: usb046d08ad-1 USB sound device
>>>>
>>>> MIDI devices (/dev/midi*)
>>>>
>>>> Mixer devices
>>>> 0: High Definition Audio AD1988B (Mixer 0 of device object 1)
>>>> 1: USB sound device (Mixer 0 of device object 3)
>>>>
>>>> Audio devices
>>>> HD Audio play front /dev/oss/oss_hdaudio0/pcm0
>>>> (device
>>>> index 0)
>>>> HD Audio play center/LFE /dev/oss/oss_hdaudio0/pcm1
>>>> (device
>>>> index 1)
>>>> HD Audio play rear /dev/oss/oss_hdaudio0/pcm2
>>>> (device
>>>> index 2)
>>>> HD Audio play side /dev/oss/oss_hdaudio0/pcm3
>>>> (device
>>>> index 3)
>>>> HD Audio play headphone /dev/oss/oss_hdaudio0/pcm4
>>>> (device
>>>> index 4)
>>>> HD Audio play spdifout-mix /dev/oss/oss_hdaudio0/spdout0
>>>> (device index 5)
>>>> HD Audio rec rec1-src /dev/oss/oss_hdaudio0/pcmin0
>>>> (device
>>>> index 6)
>>>> HD Audio rec rec2-src /dev/oss/oss_hdaudio0/pcmin1
>>>> (device
>>>> index 7)
>>>> HD Audio rec rec3-src /dev/oss/oss_hdaudio0/pcmin2
>>>> (device
>>>> index 8)
>>>> HD Audio rec spdif-in /dev/oss/oss_hdaudio0/spdin0
>>>> (device
>>>> index 9)
>>>> HD Audio play front (vmix) loopback record
>>>> /dev/oss/oss_hdaudio0/loop0
>>>> (device index 10)
>>>> USB sound device rec /dev/oss/usb046d08ad-1/pcmin0
>>>> (device index 11)
>>>>
>>>> Nodes
>>>> /dev/dsp -> /dev/oss/oss_hdaudio0/pcm0
>>>> /dev/dsp_in -> /dev/oss/oss_hdaudio0/pcm0
>>>> /dev/dsp_out -> /dev/oss/oss_hdaudio0/pcm0
>>>> /dev/dsp_ac3 -> /dev/oss/oss_hdaudio0/spdout0
>>>> /dev/dsp_mmap -> /dev/oss/oss_hdaudio0/pcm0
>>>> /dev/dsp_multich -> /dev/oss/oss_hdaudio0/pcm0
>>>>
>>>> _______________________________________________
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>>>
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>>
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