Hello,

I use Atom board that use drm/i915 driver to handle framebuffer.

I would like to use a function into this driver to turn off backlight but I nor sure how to make it.

For example, inside of intel_lvds.c, in drivers/gpu/drm/i915/ folder, there is a function to handle backlight:

static void intel_lvds_set_power(struct drm_device *dev, bool on)
static void intel_lvds_dpms(struct drm_encoder *encoder, int mode)

Could somebody help how to do it?

Best regards.

Ok, I change the question.

Could I write a kernel driver to disable backlight on drm/i915 ?

Best regards

It's probably not necessary to write a driver. There is likely an interface to the backlight created under your /sys or /proc folders. The name may vary somewhat depending on your kernel and module versions. For instance, on my system, I can change backlight brightness by writing to /sys/class/backlight/acpi_video0/brightness.

You can also enter a parameter, (for brightness often to one of the ACPI modules), at boot to set a particular value. The details of doing so will vary with your distribution. In debian based systems, module options can be set using a file in /etc/modprobe.d

Have you tried setpci?

setpci -s 00:02.1 F4.B=0

works on my drm/i915 video computer.