a3u: more reliable brightness control pwm

systems/atom_x86_with_32bit_uefi/extra-files/etc/initramfs-tools/modules

@@ -0,0 +1,21 @@
+# List of modules that you want to include in your initramfs.
+# They will be loaded at boot time in the order below.
+#
+# Syntax:  module_name [args ...]
+#
+# You must run update-initramfs(8) to effect this change.
+#
+# Examples:
+#
+# raid1
+# sd_mod
+
+# those lines together with the grub kernel cmdline options:
+#   rd.driver.blacklist=i915 rd.driver.blacklist=drm rd.driver.blacklist=drm_kms_helper
+# make sure that the backlight pwmgets loaded before the drm
+# stuff - this should avoid errors like:
+#   [drm] *ERROR* Failed to get the SoC PWM chip
+# resulting in the backlight brightness not being controllable
+i2c-designware-pci
+pwm_lpss
+pwm_lpss_platform

systems/atom_x86_with_32bit_uefi/grubconfig.sh

@@ -1,4 +1,4 @@
 #!/bin/bash
 
 # add some extra options to the kernel cmdline
-sed -i 's,GRUB_CMDLINE_LINUX="",GRUB_CMDLINE_LINUX="rootwait fsck.repair=yes net.ifnames=0 ipv6.disable=1 systemd.gpt_auto=0 i915.enable_rc6=1 i915.enable_fbc=1 fbcon=rotate:1 intel_idle.max_cstate=2",g' /etc/default/grub
+sed -i 's,GRUB_CMDLINE_LINUX="",GRUB_CMDLINE_LINUX="rootwait fsck.repair=yes net.ifnames=0 ipv6.disable=1 systemd.gpt_auto=0 i915.enable_rc6=1 i915.enable_fbc=1 fbcon=rotate:1 intel_idle.max_cstate=2 rd.driver.blacklist=i915 rd.driver.blacklist=drm rd.driver.blacklist=drm_kms_helper",g' /etc/default/grub