On 24.02.2015 17:43, Michel Dänzer wrote:
In the meantime, I've noticed that those symptoms are due to the headphone jack being incorrectly detected as connected. And indeed, on a different laptop I get all the same symptoms while headphones are plugged in.
So, it occurred to me to try 'the other OS' on this laptop, and the behaviour there is weird as well: No sound from the speakers even while nothing's plugged into the headphone jack. When I plug in headphones, there's a notification: "Something was just unplugged from your headphone jack" (!), then sound works as expected through the headphones. When I unplug them again, there's a notification: "Something was just plugged into your headphone jack".
Since this was happening in the pre-installed Windows as well, I finally convinced myself that this couldn't be (purely) a software issue and contacted HP support. Thankfully I bought extended warranty including on-site support, so today a technician came, and after he exchanged the audio board, everything's working as expected out of the box in both OSs. Thanks to everyone who made that possible in Linux, and especially to you Takashi-san for trying to help me with this problem, which turned out to be unsolvable in software.