Re: [PATCH 2/2] ARM: dts: NSP: avoid unnecessary probe deferrals
From: Florian Fainelli <f.fainelli@gmail.com>
Date: 2019-10-25 17:26:16
Also in:
linux-devicetree, linux-gpio, lkml
On 10/24/19 9:00 PM, Chris Packham wrote:
The pinctrl node is used by the gpioa node. Which may have more descendants at a board level. If the pinctrl node isn't probed first the gpio is deferred and anything that needs a gpio pin on that chip is also deferred.
If what you care is to optimize your boot flow such that no re-probing occurs, maybe another solution to look at is to re-order the order in which subsystems are initialized or built (_initcall changes or drivers/Makefile changes), because changing Device Tree certainly does not scale over platforms and I recall Rob indicating that he wanted to introduce randomized platform_device creation from of_platform_bus_populate() at one point or another.
Normally we and nodes in the device tree to be listed in their natural memory mapped address order but putting the pinctrl node first avoids the deferral of numerous devices so make an exception in this case.
That is a workaround more than a real solution, though I understand why you would to do that. One downside is that the entries are no longer in incrementing register address order and that is visually disturbing and who knows, maybe a drive by contributor whose pet project will be to order the Device Tree entries by incrementing addresses will change that in the future...
quoted hunk ↗ jump to hunk
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz> --- arch/arm/boot/dts/bcm-nsp.dtsi | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)diff --git a/arch/arm/boot/dts/bcm-nsp.dtsi b/arch/arm/boot/dts/bcm-nsp.dtsi index da6d70f09ef1..dd7a65743c08 100644 --- a/arch/arm/boot/dts/bcm-nsp.dtsi +++ b/arch/arm/boot/dts/bcm-nsp.dtsi@@ -172,6 +172,13 @@ #address-cells = <1>; #size-cells = <1>; + pinctrl: pinctrl@3f1c0 { + compatible = "brcm,nsp-pinmux"; + reg = <0x3f1c0 0x04>, + <0x30028 0x04>, + <0x3f408 0x04>; + }; + gpioa: gpio@20 { compatible = "brcm,nsp-gpio-a"; reg = <0x0020 0x70>,@@ -458,13 +465,6 @@ "sata2"; }; - pinctrl: pinctrl@3f1c0 { - compatible = "brcm,nsp-pinmux"; - reg = <0x3f1c0 0x04>, - <0x30028 0x04>, - <0x3f408 0x04>; - }; - thermal: thermal@3f2c0 { compatible = "brcm,ns-thermal"; reg = <0x3f2c0 0x10>;
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