Douglas Anderson 691c1fcda5 regulator: core: Shorten off-on-delay-us for always-on/boot-on by time since booted ... This is very close to a straight revert of commit 218320fec2 ("regulator: core: Fix off-on-delay-us for always-on/boot-on regulators"). We've identified that patch as causing a boot speed regression on sc7180-trogdor boards. While boot speed certainly isn't more important than making sure that power sequencing is correct, looking closely at the original change it doesn't seem to have been fully justified. It mentions "cycling issues" without describing exactly what the issues were. That means it's possible that the cycling issues were really a problem that should be fixed in a different way. Let's take a careful look at how we should handle regulators that have an off-on-delay and that are boot-on or always-on. Linux currently doesn't have any way to identify whether a GPIO regulator was already on when the kernel booted. That means that when the kernel boots we probe a regulator, see that it wants boot-on / always-on we, and then turn the regulator on. We could be in one of two cases when we do this: a) The regulator might have been left on by the bootloader and we're ensuring that it stays on. b) The regulator might have been left off by the bootloader and we're just now turning it on. For case a) we definitely don't need any sort of delay. For case b) we _might_ need some delay in case the bootloader turned the regulator off _right_ before booting the kernel. To get the proper delay for case b) then we can just assume a `last_off` of 0, which is what it gets initialized to by default. As per above, we can't tell whether we're in case a) or case b) so we'll assume the longer delay (case b). This basically puts the code to how it was before commit 218320fec2 ("regulator: core: Fix off-on-delay-us for always-on/boot-on regulators"). However, we add one important change: we make sure that the delay is actually honored if `last_off` is 0. Though the original "cycling issues" cited were vague, I'm hopeful that this important extra change will be enough to fix the issues that the initial commit mentioned. With this fix, I've confined that on a sc7180-trogdor board the delay at boot goes down from 500 ms to ~250 ms. That's not as good as the 0 ms that we had prior to commit 218320fec2 ("regulator: core: Fix off-on-delay-us for always-on/boot-on regulators"), but it's probably safer because we don't know if the bootloader turned the regulator off right before booting. One note is that it's possible that we could be in a state that's not a) or b) if there are other issues in the kernel. The only one I can think of is related to pinctrl. If the pinctrl driver being used on a board isn't careful about avoiding glitches when setting up a pin then it's possible that setting up a pin could cause the regulator to "turn off" briefly immediately before the regulator probes. If this is indeed causing problems then the pinctrl driver should be fixed, perhaps in a similar way to what was done in commit d21f4b7ffc ("pinctrl: qcom: Avoid glitching lines when we first mux to output") Fixes: 218320fec2 ("regulator: core: Fix off-on-delay-us for always-on/boot-on regulators") Cc: Christian Kohlschütter <christian@kohlschutter.com> Signed-off-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20230313111806.1.I2eaad872be0932a805c239a7c7a102233fb0b03b@changeid Signed-off-by: Mark Brown <broonie@kernel.org>		2023-03-14 13:30:50 +00:00
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accel
accessibility
acpi
amba
android
ata
atm
auxdisplay
base
bcma
block
bluetooth
bus
cdrom
char	tpm: disable hwrng for fTPM on some AMD designs	2023-03-12 23:28:10 +02:00
clk
clocksource
comedi
connector
counter
cpufreq
cpuidle
crypto	This push fixes a regression in the caam driver.	2023-03-05 11:32:30 -08:00
cxl
dax
dca
devfreq
dio
dma
dma-buf
edac
eisa
extcon
firewire
firmware
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fsi
gnss
gpio
gpu	Merge tag 'amd-drm-fixes-6.3-2023-03-09' of https://gitlab.freedesktop.org/agd5f/linux into drm-fixes	2023-03-10 14:17:35 +10:00
greybus
hid	for-linus-2023030901	2023-03-09 10:17:23 -08:00
hsi
hte
hv
hwmon
hwspinlock
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i2c	i2c: dev: Fix bus callback return values	2023-03-09 22:07:52 +01:00
i3c
idle
iio
infiniband
input
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iommu
ipack
irqchip
isdn
leds
macintosh
mailbox
mcb
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media	media: i2c: ov2685: convert to i2c's .probe_new()	2023-03-09 21:59:04 +01:00
memory
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message
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misc	misc: ad525x_dpot-i2c: Convert to i2c's .probe_new()	2023-03-09 21:58:45 +01:00
mmc
most
mtd	* regression fix for the notifier handling of the I2C core	2023-03-11 09:24:05 -08:00
mux
net	Networking fixes for 6.3-rc2, including fixes from netfilter, bpf	2023-03-09 10:56:58 -08:00
nfc
ntb
nubus
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nvme
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of
opp
parisc
parport
pci
pcmcia
peci
perf
phy
pinctrl
platform	platform: mellanox: mlx-platform: Initialize shift variable to 0	2023-03-07 12:08:30 +01:00
pnp
power
powercap
pps
ps3
ptp
pwm
rapidio
ras
regulator	regulator: core: Shorten off-on-delay-us for always-on/boot-on by time since booted	2023-03-14 13:30:50 +00:00
remoteproc
reset
rpmsg
rtc
s390
sbus
scsi	SCSI fixes on 20230310	2023-03-10 20:45:53 -08:00
sh
siox
slimbus
soc
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spi
spmi
ssb
staging	staging: r8188eu: delete driver	2023-03-09 10:06:28 +01:00
target	scsi: target: iscsi: Fix an error message in iscsi_check_key()	2023-03-06 16:50:42 -05:00
tc
tee
thermal
thunderbolt
tty	serial: sc16is7xx: Convert to i2c's .probe_new()	2023-03-09 21:58:53 +01:00
ufs	scsi: ufs: mcq: qcom: Clean the return path of ufs_qcom_mcq_config_resource()	2023-03-06 18:33:12 -05:00
uio
usb
vdpa
vfio
vhost
video
virt
virtio
vlynq
w1	w1: ds2482: Convert to i2c's .probe_new()	2023-03-09 21:58:57 +01:00
watchdog
xen
zorro
Kconfig
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