Re: [linux-sunxi] Re: [PATCH 52/54] arm64: dts: allwinner: Remove regulator-ramp-delay
From: Chen-Yu Tsai <hidden>
Date: 2021-08-06 12:06:12
Also in:
linux-devicetree
On Fri, Aug 6, 2021 at 7:49 PM Icenowy Zheng [off-list ref] wrote:
在 2021-07-22星期四的 10:16 +0200，Maxime Ripard写道：quoted
On Thu, Jul 22, 2021 at 12:55:53AM -0500, Samuel Holland wrote:quoted
On 7/21/21 9:04 AM, Maxime Ripard wrote:quoted
The regulator-ramp-delay property isn't documented in the binding for the AXP806, and it's ignored by the driver. Remove those properties.This is a generic regulator property, parsed by of_get_regulation_constraints, which is called by regulator_of_get_init_data in the regulator core. And it appears in bindings/regulator/regulator.yaml. I believe the binding needs to be fixed, not the device trees.It's indeed parsed by the regulator framework, but then it calls into the driver if that property is set using set_ramp_delay if it's set.Not only is it used for set_ramp_delay, but it's also used to calculate a post-change delay, see the following position (it can be overrided by a custom set_voltage_time in the driver): https://elixir.bootlin.com/linux/latest/source/drivers/regulator/core.c#L3339
Having just dug through the regulator core code at work, I agree. Furthermore, the commit log for this addition specifically mentions the reason for adding this property is to provide a (guessed) ramp rate for the core to do a proper delay for the regulator to ramp up, not to set the actual ramp rate in hardware. ChenYu [1] https://git.kernel.org/torvalds/c/fe79ea577be81e1e71642826ab00e676dc59c194
quoted
https://elixir.bootlin.com/linux/latest/source/drivers/regulator/core.c#L1378 We don't set that hook for the AXP806 DCDC-A and DCDC-E regulators (that use AXP_DESC_RANGES) at all: https://elixir.bootlin.com/linux/latest/source/drivers/regulator/axp20x-regulator.c#L343 And the only implementation we have (set for AXP_DESC and AXP_DESC_IO) works only for the AXP209: https://elixir.bootlin.com/linux/latest/source/drivers/regulator/axp20x-regulator.c#L368 So, it just looks like those properties have never been tested since they were just ignored. Maxime-- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscribe@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/linux-sunxi/68e4820ead3107aa4e80dcaf9243bd11de5fce98.camel%40aosc.io.
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