2018-04-24 19:57 GMT+02:00 Rich Felker <dalias@xxxxxxxx>: > On Tue, Apr 24, 2018 at 07:30:40PM +0200, Bartosz Golaszewski wrote: >> From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx> >> >> Device tree based systems often use OF_DECLARE() macros for devices >> that need to be initialized early in the boot process such as clocks, >> timers etc. However platform devices are more desirable. >> >> This series aims at introducing support for early platform drivers for >> OF-based systems. >> >> The idea is to have a special compatible fallback string: "earlydev" >> that similarily to "syscon" would be added to device nodes that need >> early probing. We then need to call of_early_platform_populate() early >> in the boot process to actually probe the registered devices. > > This makes no sense to me. It's not the device tree that should > contain the knowledge that these need to be registered/probed early in > the boot. That need is a property of the operating system/device > drivers, and so the *drivers* should be the ones that contain the > knowledge. > >> I am aware that this new compatible does not strictly correspond with >> the "hardware description only" rule of DT, but we already have many >> functionalities that break this rule: syscon, gpio hogs etc. >> >> The first user of this new functionality will be the DaVinci platform >> for which we want to probe the pll, psc and timer drivers early in the >> boot sequence but keep them implemented as platform drivers. >> >> In the future, if this series gets accepted, this could become and >> alternative to TIMER_OF_DECLARE, CLK_OF_DECLARE etc. and could lead >> to deprecating of those macros in favor of early platform drivers. > > This seems completely unacceptable, in that it would render new > kernels unable to boot on existing device trees (which may be > hard-coded in rom on existing devices). > Just ot make it clear: by deprecating I meant not accepting any new users, not blindly replacing the current ones. Thanks, Bart -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
