[Buildroot] ALSA don't work

Mon Oct 8 13:49:04 UTC 2012

8.10.2012 14:44, Martin Peevski kirjoitti:
>
>> My bad. I forgot that in buildroot that hidden linux .config file  is
>> located  under the
>> buildroot/output/build/linux/-linux_version///directory
>
> Oh, sorry.
> Yes, I see now the .config file and have the following configuration
> the things you show me above:
>
> #CONFIG_SND_ATMEL_AC97C is not used
> CONFIG_BUS_AC97C=y         is entirely missing but it's missing  and
> for the system which works with another rootfs
> CONFIG_SND_AT91_SOC_SAM9G20_WM8731=y
> CONFIG_SND_SOC_WM8731=y
>
> How you think, is it possible Buildroot to change my custom Kernel for
> which I'm supplied custom defconfig file?
>

So you did not give buildroot the default config file (at91sam9g45) but
used your own ?
(see at91sam9g45_linux_default_config.png)

The default at91sam9g45_defconfig file that is shipped with Linux kernel
and which buildroot uses if no custom file provided does not
by default seem to contain the needed drivers. (see
at91sam9g45_linux_default_config2.png)

Only CONFIG_SND_ATMEL_AC97C=y is defined.

>>
>> Please see the attached linux_config.png file.
>> That also shows how to check if you have the right drivers compiled.
>>
>> If you want to know how to check your drivers from actual /running/
>> rootfs then
>> please check attached file checking_linux_config_from_running_system.png
>>
>> Also, I have a very rudimentary linux config file for your board
>> (at91sam9g45_config file)
>>
>> To use it just do the following:
>> 1 ) Go to your buildroot directory
>>
>>  cd
>> /home/martin/Desktop/pm9g45-test/Development/rootFS/buildRoot/buildRoot/buildroot
>>
>> 2 ) Clean everything
>> make clean
>>
>> 3) Make a minimal buildroot config, just uClibc, busybox  and kernel
>> make menuconfig
>>
>> From the buildroot Kernel section check the following (see
>> buildroot_config.png):
>> - Kernel configuration (Using a custom config file)
>> -
>> /your_directory_where_you_saved_my_custom_linux_config/at91sam945_config
>>
>> Keep the device management still static, /dev/management (Static
>> using device table) under
>> System configuration section. No need to use mdev (or udev) yet
>> unless this won't work.
>>
>> 4) Double-check that kernel options are good before starting building
>> (check especially the Sound section under Device Drivers):
>>
>> make linux-menuconfig
>>
>> 5 ) If buildroot config and linux kernel config looks good then build
>> and pray
>>
>> make
>>
>>
>> If that rootfs still does not have sound working then maybe it's time
>> to try mdev (or udev).
>>
>>
>>
>>>> Still no sound for me. Can't run alsamixer. The attached file is
>>>> with the edited device_table.txt which include and the audio nodes
>>>> in /dev.
>>>> I want to ask you some more questions:
>>>>
>>>> 1. Shall I do make clean when I made some addition to the System
>>>> configuration or just make is fine?
>>>>
>>>> 2. Someone told me that he's doing such a task - making ALSA works
>>>> with Dynamic /dev population and udev, using built-in drivers not
>>>> modules for the Kernel. I try it out in Buildroot but was
>>>> impossible to bild the system because error. However, please tell
>>>> me, will such a System configuration makes my sound works? During
>>>> that time i will configure the system in that way and will send you
>>>> later the error message from Buildroot.
>>>>
>> mdev (or udev) will just handle the device population automatically
>> under /dev.
>> If your kernel does not have the right settings and drivers compiled
>> either directly into to the kernel or alternatively
>> as runtime loadable modules then mdev won't help either.
>>
>> In another words: *If the **drivers are not there *then using static
>> device tables, mdev, or udev will be useless.
>>
>> Also, if you have not used your own custom kernel config file for
>> your board, but the default config file, then it's
>> a very high change that it does not have the needed drivers built-in.
>>
>>>> Thanks for the help! Martin.
>>>>
>>>>
>>>>
>>>>
>>> Sorry, hit the Send button too early! :) Only to notice that at the
>>> moment I haven't  server to supply my custom Kernel version and now
>>> I'm building only the rootfs without the Kernel. However, I build
>>> the system with the same toolchain which was used for the Kernel
>>> building begore. I hope that this isn't problem, is that true?
>>>
>>>
>> No, it's not a problem to use the same toolchain but I still suspect
>> that your kernel is missing something and that is a problem.
>> (Can't check that because I didn't get your dmesg output or your
>> linux config file.)
>>
>>> Sorry once again and hava a nice day!
>>> Martin
>>
>> No prob.
>> Stefan
>
>
> Thanks for the great help, Stefan, but I try it with mdev because I
> have no time to spent on that problem. Afer some cofiguration of the
> target roots manually, and rebuild, it works! :) Now is possible to
> start alsactl init, alsamixer , a play, asound. But:
>
>    1. Configure the ALSA with the fololwing commands:
>
> # alsactl init
> Found hardware: "WM8731" "" "" "" ""
> Hardware is initialized using a generic method
> #
> # aplay -l
> **** List of PLAYBACK Hardware Devices ****
> card 0: AT91SAMG20EK [AT91SAMG20-EK], device 0: WM8731 PCM WM8731-0 []
>   Subdevices: 1/1
>   Subdevice #0: subdevice #0
> #
>
> Attached are the configurations for the Playback and Capture devices
> made with alsamixer program.
>
>
>    2. start arecord  with the command:
>        arecord -d 10 -t wav test68.wav       
>        but when I try to hear the created file with aplay nothing was
> heared. Next copy the test68.wav to my PC and try there aplay also
> nothing. Note that when I start aplay with another wav file on my
> target, aplay not release the console and nothing is heared again.
> Then I use ctrl + c to release it.
>

There is also a simpler way to test wav play.

Give command:

speaker-test -t wav -c2

It will play a loop of "Front Left, Front Right" untill you exit with Ctrl-C

>
> Can you, please check the result from the commands and the attachments
> and help me turn at least aplay with ready wav files in the rootfs?
>

Your alsactl init output is missing some information.

Compare to mine:

alsactl init
Found hardware: "ICH" "Sigmatel STAC9700,83,84" "AC97a:83847600"
"0x8086" "0x0000"

(see also my_alsa_detection.png)

So your alsactl init gives just your sound chip name and nothing else.

Also, your alsamixer outputs seemed very weird and I noticed that in
both screenshots
there is no Chipset found.

(see my version  my_alsa_mixer_settings.png)

This is a dump question but:

Are you *absolutely sure* that you are using the right kernel sources
and the right custom
kernel .config file for your kernel ?
And also are you sure that CONFIG_SND_ATMEL_AC97C=y is not needed in
your kernel ?

I still suggest you do the live running kernel config capture from your
working system like
I showed you in checking_linux_config_from_running_system.png from my
previous post
and compare it's settings to buildroot one.

Other than that, Im out of ideas.

Best regards
Stefan

> Thanks again, Martin!
>
>
>  
>
>
>
>
>

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