====== Mini PC Intel Pentium J3710 ======

===== Video card problem with kernel 6.12 =====

Using **Debian 13 Trixie** with **kernel 6.12.69**, the screen goes blank (no HDMI signal) as soon as it switches to frame buffer. With **dmesg** you can read the following errors:

<code>
[    6.587061] i915 0000:00:02.0: [drm] timed out waiting for [ENCODER:98:HDMI B] port ready: got 0xf, expected 0x0
[   16.775053] i915 0000:00:02.0: [drm] *ERROR* [CRTC:53:pipe A] flip_done timed out
[   27.015096] i915 0000:00:02.0: [drm] *ERROR* flip_done timed out
[   27.015122] i915 0000:00:02.0: [drm] *ERROR* [CRTC:53:pipe A] commit wait timed out
[   37.255074] i915 0000:00:02.0: [drm] *ERROR* flip_done timed out
[   37.255097] i915 0000:00:02.0: [drm] *ERROR* [CONNECTOR:99:HDMI-A-1] commit wait timed out
[   47.495072] i915 0000:00:02.0: [drm] *ERROR* flip_done timed out
[   47.495095] i915 0000:00:02.0: [drm] *ERROR* [PLANE:32:primary A] commit wait timed out
[   57.735072] i915 0000:00:02.0: [drm] *ERROR* [CRTC:53:pipe A] flip_done timed out
[   57.932964] i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device
</code>

The only way to boot Debian 13 with kernel 6.12 is to pass the **nomodeset** kernel parameter.

===== Kernel 6.1 =====

It is possible to install **kernel 6.1.0** from **Debian 12 Bookworm**, so that frame buffer works:

<code>
[    5.399065] fbcon: i915drmfb (fb0) is primary device
[    5.438998] Console: switching to colour frame buffer device 128x37
[    5.458533] i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device
</code>

Despite the HDMI monitor is connected, the status pseudfile reports that it is **disconnected**:

<code>
cat /sys/class/drm/card0-HDMI-A-1/status
disconnected
</code>

Writing the **on** string to the file changes the status to connected:

<code>
echo on > /sys/class/drm/card0-HDMI-A-1/status
cat /sys/class/drm/card0-HDMI-A-1/status
connected
</code>

but it causes a kernel trace:

<code>
[   69.315446] i915 0000:00:02.0: timed out waiting for [ENCODER:94:HDMI B] port ready: got 0xf, expected 0x0
</code>

When the **i915** kernel module is loaded, you can find five **DRM** (Direct Rendering Manager) devices managed by **card0**:

<code>
ls -1 /sys/class/drm/
card0
card0-DP-1
card0-DP-2
card0-HDMI-A-1
card0-HDMI-A-2
card0-HDMI-A-3
renderD128
version
</code>

It is possibile to do a **complete hardware reset** of the cards using the following command:

<code>
echo "0000:00:02.0" > /sys/bus/pci/drivers/i915/unbind
sleep 1
echo "0000:00:02.0" > /sys/bus/pci/drivers/i915/bind
</code>

After the //unbind// you can verify that the directory **/sys/class/drm/** is empty, it will be populated again after the //bind//.

===== Blanking the Virtual Terminal =====

When the host is started in frame buffer text console, the **setterm** command can be used to force the screen to go blank:

<code>
setterm --blank force
setterm --powerdown 0
</code>

The monitor turns off due no signal and remains blank even keys are pressed on the keyboard.

To revive the screen:

<code>
setterm --blank poke
setterm --powerdown 0
</code>

If the screen is blanked the following command returns **1**:

<code>
setterm --blank
1
</code>

===== Pygame =====

We verified what driver uses the Pygame app:

<code python>
import pygame
pygame.init()
print(pygame.display.get_driver())
</code>

It says **KMSDRM**.

Using that driver the SDL **Simple DirectMedia Layer** library owns the DRM master, external tools (modetest, sysfs) do not work for blanking the screen. The correct solution is to control this from inside SDL.