Hello, I have a problem with the panel on my Tegra Chromebook taking longer than expected to be ready during boot (Stéphane Marchesin reported what is basically the same issue in [0]), and have looked into ordered probing as a better way of solving this than moving nodes around in the DT or playing with initcall levels. While reading the thread [1] 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 registering devices as they are referenced by other devices. This basically reuses the information that is already implicit in the probe() implementations, saving us from refactoring existing drivers or adding information to DTBs. Something I'm not completely happy with is that I have had to move the call to of_platform_populate 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. For machs that don't move of_platform_populate() to a later point, these patches shouldn't cause any problems but it's not guaranteed that we'll avoid all the deferred probes as some drivers may not be registered yet. I have tested this on boards with Tegra, iMX.6 and Exynos SoCs, and these patches were enough to eliminate all the deferred probes. With this series I get the kernel to output to the panel in 0.5s, instead of 2.8s. Regards, Tomeu [0] http://lists.freedesktop.org/archives/dri-devel/2014-August/066527.html [1] https://lkml.org/lkml/2014/5/12/452 Tomeu Vizoso (21): regulator: core: Reduce critical area in _regulator_get ARM: tegra: Add gpio-ranges property ARM: tegra: Register drivers before devices ARM: EXYNOS: Register drivers before devices ARM i.MX6q: Register drivers before devices of/platform: Add of_platform_device_ensure() of/platform: Ensure device registration on lookup 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 clk: Probe clk providers on demand pinctrl: Probe pinctrl devices on demand phy: core: Probe phy providers on demand dma: of: Probe DMA controllers on demand power-supply: Probe power supplies on demand arch/arm/boot/dts/tegra124.dtsi | 1 + arch/arm/mach-exynos/exynos.c | 4 +-- arch/arm/mach-imx/mach-imx6q.c | 12 ++++----- arch/arm/mach-tegra/tegra.c | 21 ++++++--------- drivers/clk/clk.c | 3 +++ drivers/dma/of-dma.c | 3 +++ 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 | 53 +++++++++++++++++++++++++++++++++++++ drivers/phy/phy-core.c | 3 +++ drivers/pinctrl/devicetree.c | 2 ++ drivers/power/power_supply_core.c | 3 +++ drivers/pwm/core.c | 3 +++ drivers/regulator/core.c | 45 +++++++++++++++---------------- drivers/usb/phy/phy.c | 3 +++ drivers/video/backlight/backlight.c | 3 +++ include/linux/of_platform.h | 2 ++ 19 files changed, 130 insertions(+), 45 deletions(-) -- 2.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
