I've a Dell XPS 13 (9350) running Debian Stretch.  I have not yet replaced the Broadcom wireless until, or upgraded to a 4.4 kernel with support for it, but expect to do so in the future. After I enter the encrypted LVM password, the screen turns black and the system becomes unresponsive indefinitely.  Virtual consoles do not work.  If I then sleep and wake the machine, then suddenly X runs normally.  I can sleep and wake the machine either by closing and reopening the screen, or by pressing the power button, waiting and then pressing it again. If I disable aspects of the i915 support, like say by the kernel option nomodeset or i915.modeset=0, then the system remains on a text virtual console and spends about a minute with a flickering screen and flaky keyboard, but afterwards runs okay in text mode.  In this second scenario, there are errors related to both the bluetooth on the broadcom chip and the i915 sound support.  There are many errors in dmesg but importantly bluetooth appears to initialize successfully on the initial bootup, when the screen and keyboard do not work, but does not initialize after restart.  I therefore suspect the broadcom drivers are screwing up the i915 drivers.  Does this sound realistic?  Am I likely to fix the problem simply by dumping the Broadcom chip?  Or fixing it by using a 4.4 kernel?I've tried blacklisting btbcm in /etc/modprobe.d/blacklist.conf but apparently the kernel still loads it.  Also, adding i915 to /etc/initramfs-tools/modules makes it impossible to enter the LVM password, but I noticed some braodcom drivers get added, so maybe I must pull those out somehow.
Screen locks up until after resume
linux;suspend;broadcom;i915