Re: Is it possible to install Debian in such a case.
On Thu 27 Jun 2019 at 17:20:16 (-0400), Gene Heskett wrote:
> On Thursday 27 June 2019 14:13:22 David Wright wrote:
> > On Thu 27 Jun 2019 at 18:44:59 (+0300), Reco wrote:
> > > On Thu, Jun 27, 2019 at 10:24:51AM -0500, David Wright wrote:
> > > > That has led to finding these lines in systemd's journal:
> > >
> > > ...
> > >
> > > > Jun 27 09:47:06 west systemd-backlight[615]: [0;1;31mFailed to
> > > > write system 'brightness' attribute: Input/output error[0m
> > >
> > > ...
> > >
> > > > which suggests there's something wrong with the backlight.
> > >
> > > Hardly. More likely there's something wrong with the appropriate
> > > kernel facility.
> >
> > I'm afraid that's unlikely, based on the evidence that you snipped:
> > > On Fri 10 May 2019 at 13:20:39 -0500, David Wright wrote:
> > > > My interest in this stems from a Laptop on which you are blind
> > > > until the kernel loads (ie text pours down the screen). No
> > > > boot selection menu, no CMOS screens, no Grub screens.
> >
> > ↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑
> >
> > When the laptop is being powered up regularly, the display works for
> > about as long as the progress bar on the DELL screen takes to cross
> > from side to side: I would estimate it's about one second. The problem
> > came on gradually in Jan 2017. During use, the screen would flicker
> > a little, then die.
> >
> > So my strategy was (1) set the CMOS to boot USB/optical/hard drive in
> > that order. I did that a year ago, after it had been powered off for
> > a week. (2) Leave a stretch installation USB stick by it, ready for
> > whenever I got a chance to use it. (3) Go on holiday. When I got
> > back, I had a long enough period with a display showing to get to:
> > […]
> > at which point I'm home and dry.
> >
> > > Basically what this systemd unit tries to do is to write a saved
> > > value to /sys/class/backlight/intel_backlight/brightness.
> > > Kernel responds to this with EIO, which is unusual for the laptop
> > > (to be expected for the desktop as there's no backlight there).
> > >
> > > It may be possible to workaround this with certain knobs of i915
> > > kernel module (enable_dpcd_backlight or invert_brightness), I'd try
> > > the latter first.
> > > I.e. try adding "i915.invert_brightness=1" or
> > > "i915.enable_dpcd_backlight=1" to the kernel's commandline.
> >
> > Yes, I've also looked at the values from /sys/…/*backlight/… and they
> > all behave sensibly. But the screen flickers a little, then goes out.
> > That's why I think it might be something like a capacitor charging up.
> > Over a period of weeks, it could discharge back to behaving normally.
> >
> > But I'm not looking for a fix to the problem, just workarounds to make
> > it possible to do things like install, that require the early screens
> > which the external monitor won't display.
>
> That sounds an awful lot like the filter caps have failed. If handy with
> a small screwdriver, open that lappy and check all the aluminum cans
> for bulging where the scratches are across the tops. And if possible
> since the psu bricks are well sealed, try a fresh psu. If the cans have
> bulged tops, that's a sure sign the electrical characteristic called ESR
> has gone above and ohm or so. Unless you are handy with a workstation
> type soldering kit, its probably less trouble to just replace the lappy
> with a new one. There was a period a decade back where the capacitors
> were legendarily bad. Your unit may have some of them in it.
I thought you might pop by! I agree, but I don't think I'll be opening
it up. It went through a bad patch about 8 years ago when it would
just turn itself off (as if you'd held the power button) at random
times, but usually when adjusting the screen angle. Then I had a
failing battery (the large one), during which it was the sole PC I had
access to. Later, the spare smaller battery became worn out, so now it
runs permanently connected to a monitor and the mains PSU. I only run
it because it's fast (2 cores at 1.2GHz) though it does run hot.
AFAICT the PSU is ok as I have a spare that makes no difference. But
it's not worth spending any money on.
Cheers,
David.
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