CONFIG_X86_INTEL_LPSS prevents xorg intel drivers initialization
by Tio Pepe from LinuxQuestions.org on (#548XY)
I am working on an Intel(R) Atom(TM) x5-Z8350 based hardware running a yocto embedded distrbution on it.
My first problem was that I was unable to access mmcblk devices in it. Following comments on https://github.com/coreos/bugs/issues/209 I was able to solve it by compiling a kernel with CONFIG_X86_INTEL_LPSS set.
But, when I run a kernel with CONFIG_X86_INTEL_LPSS flag set, xorg fails to install intel modesetting drivers (/usr/lib/xorg/modules/drivers/modesetting_drv.so) because it is unable to find drm device (/dev/dri/card0). As Intel specific drivers fail to load, xorg falls back to standard VESA drivers, losing hardware acceleration and RandR support.
I have tried linux 4.9.X, 5.0.X and 5.2.X on yocto warrior and yocto zeus distributions and I always get the same result: If CONFIG_X86_INTEL_LPSS flag is present, mmcblk devices appear, drm devices are absent and xorg is unable to start Intel drivers although i915 kernel video driver is loaded. If CONFIG_X86_INTEL_LPSS is not, set, mmcblk devices disappear, drm devices are recovered and xorg initializes successfully but no mmcblk devices are available.
Does anyone know about a relation between this two features? And, what is more important, does anyone know how to circumvent this and have both devices working at the same time?
My first problem was that I was unable to access mmcblk devices in it. Following comments on https://github.com/coreos/bugs/issues/209 I was able to solve it by compiling a kernel with CONFIG_X86_INTEL_LPSS set.
But, when I run a kernel with CONFIG_X86_INTEL_LPSS flag set, xorg fails to install intel modesetting drivers (/usr/lib/xorg/modules/drivers/modesetting_drv.so) because it is unable to find drm device (/dev/dri/card0). As Intel specific drivers fail to load, xorg falls back to standard VESA drivers, losing hardware acceleration and RandR support.
I have tried linux 4.9.X, 5.0.X and 5.2.X on yocto warrior and yocto zeus distributions and I always get the same result: If CONFIG_X86_INTEL_LPSS flag is present, mmcblk devices appear, drm devices are absent and xorg is unable to start Intel drivers although i915 kernel video driver is loaded. If CONFIG_X86_INTEL_LPSS is not, set, mmcblk devices disappear, drm devices are recovered and xorg initializes successfully but no mmcblk devices are available.
Does anyone know about a relation between this two features? And, what is more important, does anyone know how to circumvent this and have both devices working at the same time?