Joachim: Thanks for your information. I will try it sooner. The test program is A Minimal Playback Program from website: http://equalarea.com/paul/alsa-audio.html
PS:Besides that test program i also used aplay to test codec ,the result is no different. qin lin Joachim Förster wrote: > > Hi qin lin, > > On Sat, 2007-07-28 at 17:04 +0800, qin lin wrote: >> I have add the driver to kernel as a module in ml403.When i insmod >> the module ,there are warnings followed here: >> [ 250.795594] snd-ml403_ac97cr: write access to codec register 0x26 >> with bad value 0x800f / 32783! >> [ 250.911545] snd-ml403_ac97cr: write access to codec register 0x26 >> with bad value 0xf / 15! >> [ 251.015576] snd-ml403_ac97cr: write access to codec register 0x2a >> with bad value 0x2801 / 10241! >> [ 251.127524] snd-ml403_ac97cr: write access to codec register 0x2a >> with bad value 0x3801 / 14337! >> >> And i check the warring find the warnings should be from function >> snd_ml403_ac97cr_codec_write() ，i have check the lm4550 codec >> datasheet to make sure the mask is what you have written. > > These warnings are ok. Codec register 0x26 is the "PowerDown > Status/Control" register and the ALSA AC97 layer tries to write ones to > the lower 4 bits (which are AFAIK read only bits). LM4550 register 0x2a > has only one valid bit (lowest), but ALSA tries to write to a not > existing bit. So my driver masks out these bits. > The warnings show the invalid numbers ALSA wants to write to these > registers. > >> What confused me is that where call the fuction >> snd_ml403_ac97cr_codec_write in the module_init program, would you >> mind if you point it for me? > > Well, the function alsa_card_ml403_ac97cr_init() is registered as the > module_init function. It registers the driver and the device to the > kernel via platform_driver/device_register(). As a consequence the > kernel will call the registered probe() function called > snd_ml403_ac97cr_probe(). Among other things, the function called > snd_ml403_ac97cr_mixer() is invoked. Finally this function registers a > mixer device and the codec_read() and codec_write() functions with the > ALSA AC97 layer. While registering the ALSA AC97 layer calls the read > and write functions several times - a kind of initialization sequence. > That's the usual structure of an ALSA driver - not that simple - I > know :-) . > >> There is another problem trouble me .I find a simple test program to >> check the codec playback work .But all it said that it cannot find >> the pcm file.Would you mind if you suggest something or paste what you >> have do to mknod the device? > > Oh, I forgot to mention that in the README file. I used the "snddevices" > script found in ALSA's alsa-driver package (form version 1.0.13, but > version shouldn't matter). > >> # ./test_sound.out /dev/snd/pcmC0D0 >> ALSA lib pcm.c:2090:(snd_pcm_open_noupdate) Unknown >> PCM /dev/snd/pcmC0D0 >> cannot open audio device /dev/snd/pcmC0D0 (No such file or directory) > > Hmmm, try to create the device files with the script from above and see > if that happens again ... > BTW: (After having created the device files) you can also use aplay > (alsa-utils package) for testing. Where did you find "test_sound"? > > Joachim > > > _______________________________________________ > Linuxppc-embedded mailing list > [email protected] > https://ozlabs.org/mailman/listinfo/linuxppc-embedded > -- View this message in context: http://www.nabble.com/Re%3A-ml403-ac97-driver-tf4164866.html#a11851202 Sent from the linuxppc-embedded mailing list archive at Nabble.com. _______________________________________________ Linuxppc-embedded mailing list [email protected] https://ozlabs.org/mailman/listinfo/linuxppc-embedded
