console.c unblank_screen problem

console.c unblank_screen problem

[Benjamin Herrenschmidt]

There is a problem with the power management code for console.c

The current code calls do_blank_screen(0); on PM_SUSPEND, and
unblank_screen() on PM_RESUME.

The problem happens when X is the current display while putting the
machine to sleep. The do_blank_screen(0) code will do nothing as
the console is not in KD_TEXT mode.
However, unblank_screen has no such protection. That means that
on wakeup, the cursor timer & console blank timers will be re-enabled
while X is frontmost, causing the blinking cursor to be displayed on
top of X, and other possible issues.

I hacked the following pacth to work around this. It appear to work
fine, but since the console code is pretty complex, I'm not sure about
possible side effects and I'd like some comments before submiting it
to Linus:

(Don't worry about the {} I added, I just noticed them and will remove
them before submitting ;)

--- 1.2/drivers/char/console.c	Sat Feb 10 18:54:15 2001
+++ edited/drivers/char/console.c	Sun Mar 25 17:57:46 2001
@@ -2595,8 +2595,9 @@
 	int currcons = fg_console;
 	int i;
 
-	if (console_blanked)
+	if (console_blanked) {
 		return;
+	}
 
 	/* entering graphics mode? */
 	if (entering_gfx) {
@@ -2660,12 +2661,16 @@
 		printk("unblank_screen: tty %d not allocated ??\n", fg_console+1);
 		return;
 	}
+	currcons = fg_console;
+	if (vcmode != KD_TEXT) {
+		console_blanked = 0;
+		return;
+	}
 	console_timer.function = blank_screen;
 	if (blankinterval) {
 		mod_timer(&console_timer, jiffies + blankinterval);
 	}
 
-	currcons = fg_console;
 	console_blanked = 0;
 	if (console_blank_hook)
 		console_blank_hook(0);

Recent problems with APM and XFree86-4.0.1

[Jamie Lokier]

Benjamin Herrenschmidt wrote:
> There is a problem with the power management code for console.c
> 
> The current code calls do_blank_screen(0); on PM_SUSPEND, and
> unblank_screen() on PM_RESUME.
> 
> The problem happens when X is the current display while putting the
> machine to sleep. The do_blank_screen(0) code will do nothing as
> the console is not in KD_TEXT mode.
> However, unblank_screen has no such protection. That means that
> on wakeup, the cursor timer & console blank timers will be re-enabled
> while X is frontmost, causing the blinking cursor to be displayed on
> top of X, and other possible issues.

On that theme of power management with X problems, I have been having
trouble with my laptop crashing when the lid is closed, instead of
suspending as it used to.  The laptop is a Toshiba Satellite 4070CDT.

The problem appeared around the time I updated the XFree86-4 package to
Red Hat 7's latest update, but I also updated to kernel 2.4.2 around
the same time so I'm not sure of the cause.

Until recently, closing the lid caused the machine to beep three times,
sync data to disk and suspend, then opening the lid resumed.  This
worked with or without X displaying.

Now if I switch to a text console and then suspend, it is fine.

If I have X displaying, closing the lid causes the machine to
beep... and beep and beep.  About half the time it does suspend after
many more beeps than usual (e.g. 10 seconds pass before deciding to sync
to disk), and in that case it usually resumes ok but sometimes it
resumes and the machine is not responding to keyboard input.  When this
happens, a hard reboot is required.  (SysRq doesn't work).

The other half of the time it just beeps repeatedly forever.  Mouse
input doesn't work, nor does keyboard.  Curiously, SysRq-S-U-B still
syncs and reboots the machine with a clean disk from this state.

These effects might have something to do with APM in current kernels
and/or XFree86-4.0.1-1 from Red Hat 7 updates.  Has anyone observed
similar recent problems?

-- Jamie

Re: Recent problems with APM and XFree86-4.0.1

[Stephen Rothwell]

Hi Jamie,

Jamie Lokier <lk@tantalophile.demon.co.uk> writes:
> 
> On that theme of power management with X problems, I have been having
> trouble with my laptop crashing when the lid is closed, instead of
> suspending as it used to.  The laptop is a Toshiba Satellite 4070CDT.

Can you please try adding
	Option	"NoPM"
to the device section of XF86Config or (XF86Config) and then try suspending
and resuming.

This made suspend/resume much more reliable on the Thinkpad 600E with
XFree86 4.  Also you could try XFree86 4.0.2, as I know that it actually
does interact with APM (4.0.1 may have as well - I am not sure).

Cheers,
Stephen Rothwell		sfr@canb.auug.org.au

Re: Recent problems with APM and XFree86-4.0.1

[Jamie Lokier]

Stephen Rothwell wrote:
> > On that theme of power management with X problems, I have been having
> > trouble with my laptop crashing when the lid is closed, instead of
> > suspending as it used to.  The laptop is a Toshiba Satellite 4070CDT.
> 
> Can you please try adding
> 	Option	"NoPM"
> to the device section of XF86Config or (XF86Config) and then try suspending
> and resuming.
> 
> This made suspend/resume much more reliable on the Thinkpad 600E with
> XFree86 4.  Also you could try XFree86 4.0.2, as I know that it actually
> does interact with APM (4.0.1 may have as well - I am not sure).

I'll try Option "NoPM", and XFree86 4.0.2 if I can find a conveniently
RH7 compatible RPM.

I should point out that I've been using _some_ version of XFree86 4
since before version 4.0 was released.  (XFree86 3 doesn't support this
laptop's video adapter).  Suspend/resume worked fine and reliably until
recently.

Another problem is that occasionally when X starts now, it will freeze
the system.  So I suspect a bug was introduced in XFree86 4.0.1.

-- Jamie

Re: Recent problems with APM and XFree86-4.0.1

[Jamie Lokier]

Jamie Lokier wrote:
> > > On that theme of power management with X problems, I have been having
> > > trouble with my laptop crashing when the lid is closed, instead of
> > > suspending as it used to.  The laptop is a Toshiba Satellite 4070CDT.
> > 
> > Can you please try adding
> > 	Option	"NoPM"
> > to the device section of XF86Config or (XF86Config) and then try suspending
> > and resuming.
> > 
> > This made suspend/resume much more reliable on the Thinkpad 600E with
> > XFree86 4.  Also you could try XFree86 4.0.2, as I know that it actually
> > does interact with APM (4.0.1 may have as well - I am not sure).
> 
> I'll try Option "NoPM", and XFree86 4.0.2 if I can find a conveniently
> RH7 compatible RPM.

I tried Option "NoRPM" with XFree86 4.0.1 and it seems to have fixed the
problem!  Yay!  Closing lid: suspend happens after a few beeps.  Open
lid, computer resumes and is working normally.  I guess the new code in
XFree86 was problematic.  Perhaps it's fixed in 4.0.2, but I haven't
tried that.

I've noticed other changes in suspend/resume.  I'm running Gnome now,
and it insists on running xscreensaver whenever I close the lid.
Somehow it is noticing the APM event, because this is very consistent.
Does anyone know how to disable this?  The setting "No screensaver"
under the list of screensavers didn't help -- it just runs a blank
screensaver which is even more confusing, because the computer appears
not to have resumed (when it's just a black screensaver).

cheers,
-- Jamie



> 
> I should point out that I've been using _some_ version of XFree86 4
> since before version 4.0 was released.  (XFree86 3 doesn't support this
> laptop's video adapter).  Suspend/resume worked fine and reliably until
> recently.
> 
> Another problem is that occasionally when X starts now, it will freeze
> the system.  So I suspect a bug was introduced in XFree86 4.0.1.
> 
> -- Jamie
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Re: Recent problems with APM and XFree86-4.0.1

[Rafael E. Herrera]

Jamie Lokier wrote:
> 
> I've noticed other changes in suspend/resume.  I'm running Gnome now,
> and it insists on running xscreensaver whenever I close the lid.
> Somehow it is noticing the APM event, because this is very consistent.
> Does anyone know how to disable this?  The setting "No screensaver"
> under the list of screensavers didn't help -- it just runs a blank
> screensaver which is even more confusing, because the computer appears
> not to have resumed (when it's just a black screensaver).

Look at the s option in the man pages for xset, that may help.

-- 
     Rafael

Re: Recent problems with APM and XFree86-4.0.1

[Jamie Lokier]

Rafael E. Herrera wrote:
> > I've noticed other changes in suspend/resume.  I'm running Gnome now,
> > and it insists on running xscreensaver whenever I close the lid.
> > Somehow it is noticing the APM event, because this is very consistent.
> > Does anyone know how to disable this?  The setting "No screensaver"
> > under the list of screensavers didn't help -- it just runs a blank
> > screensaver which is even more confusing, because the computer appears
> > not to have resumed (when it's just a black screensaver).
> 
> Look at the s option in the man pages for xset, that may help.

That is about when to blank/power down the display isn't it?

I know that xscreensaver watches for that (according to the man page),
and doesn't draw anything while the monitor's powered down.

But how do I stop xscreensaver from being started in the first place?

-- Jamie

Re: Recent problems with APM and XFree86-4.0.1

[Alain E.]

Hello Stephen,

I've just switched from 2.2.18 to 2.4.3 (on a Dell Inpiron 8000, r128 M4
adapter) and I am experimenting some problems with Xfree 4.02 (debian woody)
and (probably) APM. When I resume after a suspend, the X server
hangs. Connecting through ethernet, using strace -p `pid-of-Xfree` wake up
the Xserver. Everything is OK if I use kernel 2.2.18.  I've tryed the NoPM
option, but it is ignored by the Xserver:
(WW) R128(0): Option "NoPM" is not used

Any Idea ?


Stephen Rothwell <sfr@canb.auug.org.au> writes:

> Hi Jamie,
> 
> Jamie Lokier <lk@tantalophile.demon.co.uk> writes:
> > 
> > On that theme of power management with X problems, I have been having
> > trouble with my laptop crashing when the lid is closed, instead of
> > suspending as it used to.  The laptop is a Toshiba Satellite 4070CDT.
> 
> Can you please try adding
>       Option  "NoPM"
> to the device section of XF86Config or (XF86Config) and then try suspending
> and resuming.
> 
> This made suspend/resume much more reliable on the Thinkpad 600E with
> XFree86 4.  Also you could try XFree86 4.0.2, as I know that it actually
> does interact with APM (4.0.1 may have as well - I am not sure).
> 
> Cheers,
> Stephen Rothwell              sfr@canb.auug.org.au

-- 
Alain