Hi, while reading the thread [0] that Alexander Holler started with his series to make probing order deterministic, it occurred to me that it should be possible to achieve the same by probing devices as they are referenced by other devices.
This basically reuses the information that is already embedded in the probe() implementations, saving us from refactoring existing drivers or adding information to DTBs. The main issue I see is that the registration code path in some subsystems may not be reentrant, so some refactoring of the locking will be needed. In my testing I have found this problem with regulators, as the supply of a regulator might end up being registered during the registration of the first one. Something I'm not completely happy with is that I have had to move the population of the device tree after all platform drivers have been registered. Otherwise I don't see how I could register drivers on demand as we don't have yet each driver's compatible strings. I have done my testing on a Tegra124-based Chromebook, and these patches were enough to eliminate all the deferred probes. Regards, Tomeu [0] https://lkml.org/lkml/2014/5/12/452 Tomeu Vizoso (12): ARM: tegra: Register drivers before devices ARM: tegra: Add gpio-ranges property of/platform: add of_platform_device_ensure() gpio: Probe GPIO drivers on demand gpio: Probe pinctrl devices on demand regulator: core: Probe regulators on demand drm: Probe panels on demand drm/tegra: Probe dpaux devices on demand i2c: core: Probe i2c master devices on demand pwm: Probe PWM chip devices on demand backlight: Probe backlight devices on demand usb: phy: Probe phy devices on demand arch/arm/boot/dts/tegra124.dtsi | 1 + arch/arm/mach-tegra/tegra.c | 21 ++++++++------------- drivers/gpio/gpiolib-of.c | 5 +++++ drivers/gpu/drm/drm_panel.c | 3 +++ drivers/gpu/drm/tegra/dpaux.c | 3 +++ drivers/i2c/i2c-core.c | 3 +++ drivers/of/platform.c | 28 ++++++++++++++++++++++++++++ drivers/pwm/core.c | 3 +++ drivers/regulator/core.c | 2 ++ drivers/usb/phy/phy.c | 3 +++ drivers/video/backlight/backlight.c | 3 +++ include/linux/of_platform.h | 2 ++ 12 files changed, 64 insertions(+), 13 deletions(-) -- 2.3.6 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
