On 13-12-17, 10:42, Greg Kroah-Hartman wrote: > On Sun, Oct 29, 2017 at 07:18:51PM +0530, Viresh Kumar wrote: > > Some devices are powered ON by the bootloader before the bootloader > > handovers control to Linux. It maybe important for those devices to keep > > working until the time a Linux device driver probes the device and > > reconfigure its resources. > > > > A typical example of that can be the LCD controller, which is used by > > the bootloaders to show image(s) while the platform is booting into > > Linux. The LCD controller can be using some resources, like clk, > > regulators, PM domain, etc, that are shared between several devices. > > These shared resources should be configured to satisfy need of all the > > users. If another device's (X) driver gets probed before the LCD > > controller driver in this case, then it may end up reconfiguring these > > resources to ranges satisfying the current users (only device X) and > > that can make the LCD screen unstable. > > > > This patch introduces the concept of boot-constraints, which will be set > > by the bootloaders and the kernel will satisfy them until the time > > driver for such a device is probed (successfully or unsuccessfully). > > > > The list of boot constraint types is empty for now, and will be > > incrementally updated by later patches. > > > > Only two routines are exposed by the boot constraints core for now: > > I think we need some documentation somewhere on how to use this, right?
Will add that in next version. -- viresh
