| joerg | there's a quite tricky part in BT regarding audio iirc | 06:49 |
|---|---|---|
| joerg | grr | 06:53 |
| joerg | basically analog audio gets fed to BT chip instead of headphone amp? | 06:53 |
| joerg | my memory seems foggy | 06:53 |
| sicelo | FM audio? That seems to go to the audio codec, so i guess that part's easy enough | 10:26 |
| sicelo | It's just that for some reason, the fm part doesn't operate when the bt side is off. However, the product brief says it does. | 10:27 |
| sicelo | So either we suffer because ours is Nokia custom, or it's the way the chip is connected/controlled | 10:28 |
| joerg | or the kernel drivers(?) are "stupid"? I know they share one interface for the chip, maybe layering / dependency conflicts? | 19:48 |
| joerg | the chip isn't Nokia custom afaik | 19:49 |
| joerg | I'd suspect "killswitch" for BT TX is simply too brute force, shutting down the whole chip as much as possible | 19:50 |
| sicelo | I hope it's not the drivers :-) | 20:42 |
| sicelo | I guess you're right about it not being custom. I found that the bcm2048 is used on a couple of nokia feature phones, one or two lg phones as well as a portable media player | 20:43 |
| sicelo | Maybe I will make time to go through the driver code, and see what happens if we skip the Bluetooth check (it's in the driver) | 20:44 |
| sicelo | Pity there's zero documentation for it ... I'd try manual i2c | 20:46 |
| sicelo | joerg: but i remember on tmo, the dev who made the first working radio application for n900 (Martin Grimme, I think) specifically mentioned that there was no way for it to work without bt on | 20:55 |
| joerg | https://www.broadcom.com/site-search?q=bcm2048 | 21:12 |
| joerg | sicelo: sorry, it was FMTX that's connected to headphones lines https://i.imgur.com/zGcDxwv.png | 21:24 |
| joerg | BTFM chip (bcm2048) has FM_AUDIO_PR FM_AUDIO_PL that go straight to audio codec, unrelated to BT audio PCM interface | 21:27 |
| sicelo | Yes | 21:29 |
| sicelo | It's the activation of the fm function that's bound to bt | 21:29 |
| sicelo | The product brief says, "fm control through either bsc compatible interface or bluetooth hci" | 21:34 |
| joerg | there been a http://www.broadcom.com/products/Bluetooth/Bluetooth-RF-Silicon-and-Software-Solutions/BCM2048 but it's gone | 21:35 |
| joerg | maybe archive.com? | 21:35 |
| sicelo | Isn't that the 2-page product brief? Seems Broadcom only publishes briefs :-) | 21:37 |
| sicelo | https://web.archive.org/web/20100107153109/http://www.broadcom.com/products/Bluetooth/Bluetooth-RF-Silicon-and-Software-Solutions/BCM2048 | 21:40 |
| joerg | no idea since I can't check anymore, since... it's gone | 21:53 |
| joerg | I had a bookmark for this, no other bookmarks related to BCM2048 - I guess whan I didn't find anything back when, it's futile to get locked in to a search session like I just did | 21:54 |
| joerg | excuse me, what was the *question*? | 21:54 |
| joerg | found https://www.nokiarepairchicago.us/n85/bluetooth-and-fm-rds-radio-module.html and https://html.datasheetq.com/pdf-html/306820/Broadcom/1page/BCM2048.html?lang=en | 21:56 |
| joerg | https://www.embedded.com/fm-radio-joins-with-bluetooth-on-same-silicon/ | 21:56 |
| joerg | http://www.mjdic.com/proclass-read-id-1075910.html | 21:59 |
| joerg | and of course https://elinux.org/N900 | 22:02 |
| joerg | https://elixir.bootlin.com/linux/v4.8/source/drivers/staging/media/bcm2048/radio-bcm2048.c | 22:04 |
| joerg | aaaaand I'm out | 22:04 |
| joerg | sorry | 22:04 |
| joerg | the weirdest thing is Broadcom outright denies now that chip ever existed | 22:12 |
| joerg | a "nice" example why eventually you have to bin all your dsigns and start anew from scratch since building the old design simply became impossible due to sourcing problems | 22:14 |
| sicelo | Fun :-) | 22:16 |
| sicelo | i guess this is what you were referring to earlier - "There is no direct bypass from the FMRX hardware to the sound system (or more precisely, there is, but it cannot be used since it does not seem to filter high frequency sounds that may damage the speakers) so the sound has to be processed by the CPU." good to know this actually | 22:25 |
| joerg | how to fix the /topic to deal with infobot no more? | 23:51 |
| joerg | *sigh* btdt err dtat, particularly I asked http://reisenweber.net/irclogs/libera/_maemo/_maemo.2022-01-01.log.html#t2022-01-01T18:43:13 | 23:54 |
| joerg | http://reisenweber.net/irclogs/libera/_maemo/_maemo.2021-01-16.log.html#t2021-01-16T18:08:09 ff has a few of them | 23:58 |
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