Hi On Wed, Aug 13, 2014 at 10:40 AM, Grant Likely <grant.likely@xxxxxxxxxxxx> wrote: > On Wed, Aug 13, 2014 at 8:17 AM, Luc Verhaegen <libv@xxxxxxxxx> wrote: >> The next commit will handle clocks correctly, so that these do not get >> automatically disabled on certain SoC simplefb implementations. As a >> result, the removal of this simplefb driver, and the release of the >> clocks, is rather final, and only a full display driver can work after >> this. So, it makes sense to also flag the dt node as disabled, even >> though it has no real value today. >> >> Signed-off-by: Luc Verhaegen <libv@xxxxxxxxx> > > Please, no. > > Drivers should not be modifying the device tree without and > exceptionally good reason for doing so. Drivers are to treat the DT as > immutable. > > * the exception is an overlay driver which add new devices to the > kernel. Definitely not the case here. Why? I think we have exactly that case: * DT describes the real hw properly and those parts are immutable * Additionally, bootloaders create firmware-framebuffers and create simple-framebuffer devices for them. Those are valid as long as no driver reconfigured the real hw. * Once a real hw-driver loads, it might destroy the existing framebuffers, thus, it should also destroy the platform device. * If the real hw-driver is unloaded, it might re-create the FB and thus create a new (or enable the old) platform device. Or, in a nutshell: A "simple-framebuffer" device is basically a platform-device for framebuffers. Framebuffers can be created and destroyed during runtime. The reason we create platform-devices for them, is to allow dummy drivers to be probed. Real hw-drivers obviously bind to the parent bus device. Other ideas are obviously welcome, but so far all of the other ideas sounded like big hacks (like remove_conflicting_framebuffers() so far..). Thanks David -- To unsubscribe from this list: send the line "unsubscribe linux-fbdev" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
