Poulsbo (Italiano)

La serie Intel GMA 500, conosciuta anche con il nome in codice Poulsbo oppure Intel System Controller Hub US15W, è una famiglia di adattatori video integrati basati sul processore grafico the PowerVR SGX 535. È tipicamente montato sulla serie di processori Atom Z. Le caratteristiche includono capacità di decodifica hardware dei contenuti video fino a 720-1080 dpi in vari standard di codec, ad esempio l'H.264.

Il processore grafico PowerVR SGX 535 è stato sviluppato dall' Imagination Technologies e concesso in licenza da Intel, i driver standard opensourceIntel non funzionano con questa periferica.

In questa pagina si trovano informazioni su come ottenere il meglio dal vostro hardware Poulsbo con Arch Linux.

Modulo del kernel gma500_gfx

Con il kernel 2.6.39 Alan Cox sviluppò il modulo psb_gfx per supportare la periferica Poulsbo. A partire dal kernel 3.3.rc1 il driver è stato stabilizzato e rinominato come gma500_gfx. ([1])

Vantaggi

• Risoluzione nativa (1366x768) con i primi KMS (testato su Asus Eee 1101HA)
• Kernel e server Xorg aggiornati
• Accelerazione 2D
• Funziona out-of-the-box

Svantaggi

• Alcuni non sono in grado di ottenere la risoluzione nativa (e.g 1366x768)
• Nessuna accelerazione 3D
• Scarsa performance multimediale (l'uso di mplayer con x11 or sdl rende l'utilizzo a schermo intero un po' lento)

Per verificare se i driver sono stati caricati correttamente l'output di lsmod | grep gma dovrebbe essere il seguente:

gma500_gfx            131893  2 
i2c_algo_bit            4615  1 gma500_gfx
drm_kms_helper         29203  1 gma500_gfx
drm                   170883  2 drm_kms_helper,gma500_gfx
i2c_core               16653  5 drm,drm_kms_helper,i2c_algo_bit,gma500_gfx,videodev

Nel caso non si riuscissero a caricare i driver verificare dare il seguente comando e verificare che il campo MODULES contenga la stringa gma500_gfx.

# nano /etc/mkinitcpio.conf

 [...]

 MODULES="gma500_gfx"

 [...]

Verificare inoltre che i driver vesa siano disinstallati con il comando:

# pacman -Qs xf86-video-vesa

Se ricevete un output provvedete a disintallare i driver con il comando:

# pacman -R xf86-video-vesa

Riavviate e dovreste avere i vostri driver abilitati e funzionanti

Modesetting driver e procedura per l'uso di un monitor esterno

Puoi impostare una risoluzione diversa a un monitor esterno usando xrandr scaricando xf86-video-modesetting dai repository ufficiali. Se scegli di usare il pacchetto git (xf86-video-modesetting-git^AUR), ricordati di ricompilarlo dopo ogni aggiornamento di Xorg]. Dopo l'installazione, un file di Xorg deve essere modificato per usare il driver. Modifica quindi il file /etc/X11/xorg.conf.d/20-gpudriver.conf aggiungendo:

Section "Device"
   Identifier "gma500_gfx"
   Driver     "modesetting"
   Option     "SWCursor"       "ON" 
EndSection

Note: Questo file di configurazione rimpiazzerà i driver xf86-video-fbdev. Se non vuoi che questo accada basta occorre rimpiazzare modesetting con fbdev.

Risoluzione di problemi

Poor video performance

If you have problems playing 720p and 1080i videos, yes, that's normal while there are not accelerated XV drivers. But you can improve it up to the point of going well and smoothly for most videos (even HD ones) with these tricks:

1. add pm-powersave false to /etc/rc.local. man pm-powersave for more info.
2. use xf86-video-modesetting-git^AUR as indicated above.
3. always use mplayer or any variant/gui. VLC and others are usually much more slower.
4. substitute the normal mplayer with mplayer-minimal-svn^AUR, and compile with aggressive optimizations: -march=native -fomit-frame-pointer -O3 -ffast-math'. (About makepkg)
5. use linux-lqx^AUR as it is a very good performance kernel. Edit PKGBUILD so you can do menuconfig and make sure you select your processor and remove generic optimizations for other processors. (About kernels)

Fix suspend

Old fbdev driver (default)

If suspend does not work, there are various quirk options you can try. First, make sure that you have pm-utils and pm-quirks installed. See the manpage for pm-suspend for a list of them all. One that has been reported to help is quirk-vbemode-restore, which saves and restores the current VESA mode.

To test it, open a terminal and use the following command

# pm-suspend --quirk-vbemode-restore 

That should suspend your system. If you are able to resume, you'll want to use this option every time you suspend.

# echo "ADD_PARAMETERS='--quirk-vbemode-restore'" > /etc/pm/config.d/gma500 

If you are not able to resume and you get a black screen instead, try the above quirk command with only one dash

# pm-suspend -quirk-vbemode-restore 

Tip: If you stuck with a black screen after resume, be aware that besides the black screen, your system works fine. Instead of hard rebooting, you could try to blindly reboot your system, since the last thing you used before suspend was the terminal. Alternatively, if you have ssh enabled on your machine you could do it remotely.

modesetting xorg driver

On some machines, when using modesetting driver the screen gets messed up with random data. Although the computer still works, you must go to a console and kill X or reboot "blindly". This is not optimal, so here is a solution:

First, see your available screens and modes running xrandr:

 # xrandr
 Screen 0: minimum 320 x 200, current 1280 x 720, maximum 2048 x 2048
 LVDS-0 connected 1280x720+0+0 222mm x 125mm
   1280x720       60.0*+
 HDMI-0 connected 1280x720+0+0 531mm x 298mm
   1920x1080      60.0 +
   1680x1050      59.9  
   1680x945       60.0  
   1400x1050      74.9     59.9  
   1600x900       60.0  
   1280x1024      75.0     60.0  
   1440x900       75.0     59.9  
   1280x960       60.0  
   1366x768       60.0  
   1360x768       60.0  
   1280x800       74.9     59.9  
   1152x864       75.0  
   1280x768       74.9     60.0  
   1280x720       60.0* 
   1024x768       75.1     70.1     60.0  
   1024x576       60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   848x480        60.0  
   640x480        72.8     75.0     60.0  
   720x400        70.1

Edit or create (giving executive permissions) /etc/pm/sleep.d/99xrandr, writing the correct names and modes for your solution:

 #!/bin/sh
 #
 # turn off and on the screens so we force to clean video data
 case "$1" in
 hibernate|||suspend)
 xrandr --output LVDS-0 --off
 xrandr --output HDMI-0 --off
 ;;
 thaw|||resume)
 xrandr --output LVDS-0 --off
 xrandr --output HDMI-0 --off
 xrandr --output LVDS-0 --mode 1280x720
 /usr/local/bin/brillo-
 ;;
 *) exit $NA
 ;;
 esac

In my case, I turn off both screens, and turn on only the main screen upon awakening. Feel free to customize to your needs. On some machines, the screen turns on by default even when the system was put to sleep with the screen turned off, so you need to turn it off twice.

Note: This only works if you call pm-suspend or pm-hibernate inside X. If it is called from a daemon or a tty, it won't work.

Set backlight brightness

All that is needed to set the brightness is sending a number (0-100) to /sys/class/backlight/psblvds/brightness. This obviously requires sysfs to be enabled in the kernel, as it is in the Arch Linux kernel. To set display to minimal brightness, issue this command as root:

# echo 0 > /sys/class/backlight/psb-bl/brightness

Or, for full luminosity:

# echo 100 > /sys/class/backlight/psb-bl/brightness

A very short script is available to do this with less typing written by mulenmar.

#! /bin/sh
sudo sh -c "echo $1 > /sys/class/backlight/psb-bl/brightness"

Simply save it as brightness.sh, and give it executable permissions. Then you can use it like so:

Set brightness to minimum:

./brightness.sh 0

Set brightness to half:

./brightness.sh 50

Sudo may obviously ask for your password, so you have to be in the sudoers file. A variation of this script can be found here.

Note: If changing /sys/class/backlight/psblvds/brightness does not work, you may need to add acpi_osi=Linux acpi_backlight=vendor to your kernel parameters. After rebooting, a new folder will appear under /sys/class/backlight/; making changes to the brightness file in that folder should work. For example, in some Asus netbooks the backlight can be controlled by writing a value (0-10) to /sys/class/backlight/eeepc-wmi/brightness.

Memory allocation optimization

You can often improve performance by limiting the amount of RAM used by the system so that there will be more available for the videocard. If you have 1GB RAM use mem=896mb or if you have 2GB RAM use mem=1920mb. Add the following parameters to your bootloader's configuration file.

• Grub-legacy

Edit /boot/grub/menu.lst

...
kernel /vmlinuz-linux root=/dev/sda2 ro mem=896mb 
...

• Grub

Edit /etc/default/grub

...
GRUB_CMDLINE_LINUX="mem=896mb"
...

• Syslinux

Edit /boot/syslinux/syslinux.cfg

...
APPEND root=/dev/sda2 ro mem=896mb 
...

See also

• An experience about configuring Poulsbo (Spanish)
• Ubuntu Wiki
• Ubuntu Forums
• Ubuntu 12.04 gma500 (poulsbo) boot options (blog post)