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(This was originally posted on the Arch Linux forums, but since I'm looking for some help ASAP I've decided to get it on a few other message boards as well. ...
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  1. #1
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    Jumpy/laggy touchpad and suspend idiosyncrasies.


    (This was originally posted on the Arch Linux forums, but since I'm looking for some help ASAP I've decided to get it on a few other message boards as well. Excuse what might seem Arch-biased langauge.)

    I just got a hold of an older laptop, a Dell Latitude C640, and to my dismay setting up Linux on it hasn't been the walk in the park I'd hoped it'd be. I read a bunch of articles about Linux on this machine before I got it and most seemed to have a pretty easy time of everything. Of course this might be because the laptop is quite a few years old and older Linux kernels acted different ways, but I guess I assumed that things would be even easier using a modern distro.

    The Touchpad
    It worked fine on the install of Windows XP that came installed on it, with no problems at all. Before installing any flavor of Linux I ran Knoppix on it just kind of to make sure things would go OK. It was a little dated, being Knoppix 5.10, but I figured it'd do for my purposes.

    The first time I booted it seemed to work OK, with the mouse cursor behaving mostly as it should, with a little lag. I've used this same Knoppix disk on another laptop and it did much the same thing. After another boot, however, I saw that things weren't going to be so easy. The cursor immediately drifted off into one of the screen's corners (it didn't seem to care much which one it was in, as long as it was in one) and would refuse to come out. I could move the cursor a little ways off of the edge of the screen, but not far enough to click anything, and it would immediately go back as soon as I released my finger. So I tried a few other disks. First I tried a CD I have for Crunchbang Linux (just a minimalist, Openbox-based Ubuntu flavor), and then Knoppix 4. Both gave very similar results. Crunchbang let me have a little bit more control over the cursor for a little while after booting, maybe for about a minute, and then the same behavior cropped up. I only booted with Knoppix 4 once, but it was pretty much the same deal.

    I started reading up on what might be going on and came across a thread on the Linux Mint forums that seemed to be describing an issue very close to mine (though mine is completely unrelated to the AC adapter and persists whether it's plugged in or not). Someone in the thread suggested it was a kernel issue, since it's definitely not a hardware issue, so I then booted into a copy of DSL I had lying around, which uses the 2.4 kernel. Sure enough everything worked without problems. This caused me to believe, going by some of the conclusions from the Lnux Mint thread and apparently mistakenly, that the issue may have been with the 2.6 Debian kernels, so I figured I'd just get Arch installed and see how things went.

    After getting X set up and working properly I saw that the issue was going to be much the same. To get around the cursor being dragged into the corner against my will I found out that if I ran without HAL or that if I disabled hot-plugging I could use the touchpad, although not flawlessly. Here's xorg.conf:

    Code:
    Section "ServerLayout"
    	Identifier	"Xorg"
    	Screen		0 "Default" 0 0
    	InputDevice	"Touchpad"	"CorePointer"
    #	InputDevice	"USB Mouse"	"SendCoreEvents"
    EndSection
    
    Section "ServerFlags"
    	Option		"AllowMouseOpenFail"	"true"
    	Option		"AutoAddDevices"	"false"
    EndSection
    
    Section "Module"
    	Load		"glx"
    	Load		"dri"
    	Load		"drm"
    	Load 		"synaptics"
    EndSection
    
    Section "InputDevice"
    	Identifier	"Touchpad"
    	Driver		"synaptics"
    	Option		"SHMConfig"	"true"
    	Option		"AlwaysCore"	"true"
    	Option		"MinSpeed"	"0.05"
    	Option		"MaxSpeed"	"0.40"
    	Option		"TapButton1"	"1"
    	Option		"TapButton2"	"2"
    	Option		"FastTaps"	"1"
    	Option		"VertEdgeScroll"	"true"
    	Option		"HorizEdgeScroll"	"true"
    	Option		"Emulate3Buttons"	"true"
    EndSection
    
    #Section "InputDevice"
    #	Identifier	"USB Mouse"
    #	Driver		"evdev"
    #	Option		"SendCoreEvents"	"true"
    #EndSection
    
    Section "Monitor"
    	Identifier	"LCD"
    EndSection
    
    Section "Device"
    	Identifier	"Radeon Mobility 7500"
    	Driver		"radeon"
    EndSection
    
    Section "Screen"
    	Identifier	"Default"
    	Device		"Radeon Mobility 7500"
    	Monitor		"LCD"
    	DefaultColorDepth 24
    	SubSection "Display"
    		Depth 24
    		Modes "1024x768" "800x600" "640x480"
    	EndSubSection
    EndSection
    
    Section "DRI"
    	Group		"video"
    	Mode		0666
    EndSection
    The "AutoAddDevice" option is the only thing that seems to make any difference in usability at all; without it I can't use the touchpad at all, and with it I can, but to varying degrees. I've found that right after I boot up everything seems to work exactly how it's supposed to, but shortly after, sometimes 15 seconds, sometimes many minutes, things seem to get kind of unresponsive. The cursor will go where I want it to go, but it jumps around and does it very slowly. The mouse buttons also get very unresponsive. Right click is especially bad, and I often have to hold down the button just to get it to do what I want, but left click is very bad too, requiring me to push the button down for almost a full second, sometimes several times. Taps on the pad, after things go wrong, also stop being recognized, forcing me to use the buttons (which I'm OK with). It's usable, but the behavior is not ideal whatsoever—it's rather annoying.

    The most aggravating thing, I think, is that I can't seem to find anyone else using this same model that has this issue. The latest I've seen is from January, a comment on the Linlap page for the C640, an Ubuntu (8.10) user reporting no issues and saying he/she is very pleased.

    Suspend (both to disk and RAM)
    I actually did install the latest Crunchbang (9.04.01, the 32-bit "Lite" edition) first to see if anything would clear up by installing it rather than running the live CD, but I only had it installed for a few hours. I didn't really get into messing with xorg.conf that much yet, only really touching "FingerLow" and "FingerHigh" settings, so the touchpad issue was still nagging me. I did play around a bit though and found out that suspend to RAM and suspend to disk worked pretty much from the go, only requiring that I installed uswsusp. Issuing a simple "sudo pm-suspend" or "sudo pm-hiberate" put the computer to sleep and it woke back up without any issue at all.

    But suspend on Arch is proving to be a pain in the neck. Suspend to RAM simply will not work; the computer shuts down but will not resume, leaving me only a blank screen with an unresponsive keyboard. Suspend to disk works (using hibernate-script as pm-hibernate doesn't seem to do anything at all), but it works very poorly; both suspending and resuming take a very, very long time—so long, in fact, that I'm just better off shutting down and restarting normally, since the boot time is better. I don't know what accounts for the drastic difference in distros, and this isn't the first experience I've had with suspension working on Ubuntu but not on Arch. What is different in the Ubuntu implementation of pm-utils than the Arch way? Is it the Ubuntu kernel? Is there any way to implement the Ubuntu way with Arch (because, after all, I'd prefer to use Arch)?

    I'm considering installing Crunchbang once again if I can't get things to work the way I want them to in the next few days on Arch. And, if I can't make the touchpad work in a satisfactory manner on Cruchbang, I might just have to reinstall Windows. I don't want to do that. :/

  2. #2
    Linux Guru reed9's Avatar
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    But suspend on Arch is proving to be a pain in the neck. Suspend to RAM simply will not work; the computer shuts down but will not resume, leaving me only a blank screen with an unresponsive keyboard. Suspend to disk works (using hibernate-script as pm-hibernate doesn't seem to do anything at all), but it works very poorly; both suspending and resuming take a very, very long time—so long, in fact, that I'm just better off shutting down and restarting normally, since the boot time is better.
    I never use hibernate or suspend, but I suspect the difference between Arch and Ubuntu is that Ubuntu has it all preconfigured for you. Have you read the wiki?
    Pm-utils - ArchWiki
    Suspend to Disk - ArchWiki

    As for the touchpad, have you tried messing with the hal policies with input hotplugging enabled?

    Make sure Circular Scrolling is turned off.

    Also, gpointing-device-settings might be useful.
    It does require SHMConfig to be true. (Which with input hotplugging needs to be enabled in a hal policy.)

    You might want to run
    Code:
    synclient -m 100
    to check what the touchpad is registering.

    Touchpad Synaptics - ArchWiki

  3. #3
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    Quote Originally Posted by reed9 View Post
    I never use hibernate or suspend, but I suspect the difference between Arch and Ubuntu is that Ubuntu has it all preconfigured for you. Have you read the wiki?
    Can you elaborate what you mean about Ubuntu preconfiguring? If you mean it automatically sets up most things for me, a window manager, etc., then I don't think that's where the issue lies; if anything it'd be with the Ubuntu kernel, pm-utils, acpi, or something related. If you mean that pm-utils is preconfigured, well, then you could be right. If this is what you mean, do you think you could point me in the right direction? There has to be a difference somewhere, I just don't know where to find it.

    I'm also thoroughly familiar with both wiki entries, but neither seem to suggest anything particularly useful to my problem—the Arch wiki is usually my first stop with any issues I have anyway. I'm most curious about why pm-utils worked without any fiddling on Crunchbang.

    As for the touchpad, have you tried messing with the hal policies with input hotplugging enabled?
    Yes. As I've stated in my original post, with hotplugging enabled at all, no matter if I have a hal policy file or not, the cursor drifts into a corner and stays there.

    I've tried both the program you suggested and gsynaptics and neither do much of anything. Monitoring with synclient works fine, but doesn't show anything out of the ordinary. With hotplugging enabled the finger pressure remains at zero while the cursor moves across the screen (by itself), and with it disabled (after things act up), everything looks ordinary.

    For the last few days the cursor has moved around fine for sometimes five minutes or more, and a few times I've thought it wasn't going to act up at all, and then, inevitably, it would. I have no idea what is triggering it, but it's very annoying.

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  5. #4
    Linux Guru reed9's Avatar
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    Arch packages are for the most part as released from upstream, without custom patches or configuration. Many distros, aside from pre-configuring settings, apply their own patches to code before compiling and packaging. Beyond that, I really don't know where to look for help with suspend/hibernate. My computer boots in 15-20 seconds, so it always seemed useless. How much RAM do you have and what kind of swap space do you have and do you set it up differently in different distros? Suspend to disk needs enough swap to hold whatever is in RAM, I believe.

    For the touchpad...I'm at a loss. There is this bit in the Wiki
    Cursor Jump

    Some users have cursor to jump there and here in the screen. AT NOW doesn't exist any patch, it WILL BE FIX in future driver version.
    You could try the git package from the AUR.

  6. #5
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    If I knew where to look or what I was looking at in the pm-utils package/whatever else might be different, I'd do it. I don't though.

    Anyway, the suspend issue is really secondary to the touchpad issues. I only have 384MB ram, but ~900MB swap. I have no idea why suspend to disk takes so long on arch.

    I've also been using the synaptics-git package for a few days now with no effect. Too bad.

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