Kernel 5.4.1 audio broken on Aspire1 laptop

So frustrating! Booting easy Pyro with 5.4.1 kernel on my Aspire1 laptop, the kernel reports that there are no audio devices. Different sound configuration, different firmware? ...no, can't find any cause. The kernel just cannot find the audio device, even though it is a Intel audio chip. The laptop has the Apollo Lake series CPU.

There is another problem on that laptop. The mouse is a wired-USB type, plugged into a USB2 socket, and every now and again the mouse freezes, fixed by replugging the mouse.

The thing is, this mouse-freezing problem was not there before, with older kernels. Easy Pyro used to have 4.14.x kernels, then upgraded to 5.1.x, 5.2.x -- don't know when the freezing problem came in.

I am going to try an experiment. Have compiled the latest in the 4.14.x series, 4.14.157, and will try that.

EDIT:
I am now running Easy Pyro with 4.14.157 kernel, and audio works. However, the mouse still freezes. I get about half an hour of usage before the freeze. using it now, about another half hour, it hasn't frozen again.

In earlier tests, with later kernels (5.2.21 and 5.4.1) in most cases it is OK after the first freeze, but sometimes got the freezing happening more than once.

So it looks like a backport that has been applied to one of the 4.14.x series is the cause, but I am not going to try and find out which one. I have been down that road before, it is a very time-consuming process, to try and narrow it down to the commit that caused the problem. 

Tags: easy