At Sat, 22 Nov 2008 21:00:18 +0200, Maxim Levitsky wrote: > > Maxim Levitsky wrote: > > Andreas Mohr wrote: > >> Hi, > >> > >> On Wed, Nov 12, 2008 at 07:07:04PM +0200, Maxim Levitsky wrote: > >>> I pretty much studied the datasheet and driver, and this is what I > >>> found: > >>> btw, my acer 5720 and aspire one share same ALC268. > >>> Some stuff is trivially fixable, some seems to be unfixable at all: > >> > >> Wow, what an extremely in-depth analysis! > >> I just intended to dive into getting mic routing corrected myself, > >> thus you saved me a lot of time! > >> > >>> model=acer is used on my regular laptop. > >>> model-acer-aspire is used on aspire one laptop, and it needs to be > >>> renamed, as both are aspire. > >> > >> +1 (your analysis of both being rather different - as already pondered - > >> confirms this necessity) > >> > >>> And now for unfixable problems: > >>> > >>> 1) There is strong DC offset on all inputs. > >>> it is even different on left/right and depends on capture volume. > >>> I tried to change the VREF only param that could help, but it doesn't. > >>> I feel that this is hardware flaw. > >>> (It is possible that voltage on inputs is created by circuit made by > >>> acer, and then ALC268 amplifies it.) > >> > >> Sounds like really bad circuit design then. > >> One would think that the Intel HDA architecture might have builtin > >> measures to compensate for this if needed? DC offset issues on > >> soundcards aren't exactly a new phenomenon after all... > >> > >>> Lastly I noticed that datasheet mentions so called 'coefficients': > >>> the codecs exposes lots of internal and undocumented registers using > >>> set address/ get/set value scheme. > >>> maybe some of above bugs are fixable there, but ether realtek has to > >>> provide data for that or reverse engineering of > >>> windows driver is required. > >> > >> I've actually had a peek at the .inf files since I thought that it would > >> already contain register values in those registry keys that it creates on > >> install, but yeah, that's all in-driver it seems. > >> Probably time to ask Acer about specifics, especially since I didn't spot > >> any hda-intel changes in their linux-2.6.23.9lw source. > >> > >> Thank you very much, > >> > >> Andreas Mohr > > > > Small update: > > > > 1) The dc offset isn't present on aspire one, really is a circuit design > > bug I guess 2) Internal mic works perfectly on aspire one, can reproduce > > the strange behaver at all, > > Probably this was mixer bug. > Finally, I found how to reproduce that bug, > I mean to get normal volume on internal mic, I have to increase volume > only on left or right channel. > > So, this happens always, and _only_ when recording _mono_ sound from internal > mic. > > Since hardware doesn't support hardware mono input, tested with -D hw:0 > I suspect this to be alsa-lib bug, any ideas? > Happens with arecord -D plughw:0 -c1 . What does show with -v option? Takashi -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
