Hi all,
On Wed, 4 Sep 2019 13:42:50 +0100 Mark Brown broonie@kernel.org wrote: [...]
with Arm laptops coming on the market it's becoming more of an issue so let's do something about it.
For the record: I try to run a stock distribution kernel (lots of modules) on an Olimex Teres-I. The PMIC driver is of course a module.
In the absence of any better idea just defer the powering off for 30s after late_initcall(), this is obviously a hack but it should mask the issue for now and it's no more arbitrary than late_initcall() itself. Ideally we'd have some heuristics to detect if we're on an affected system and tune or skip the delay appropriately, and there may be some need for a command line option to be added.
Am I the only one having problems with this change? I get
[ 11.917136] anx6345 0-0038: 0-0038 supply dvdd12-supply not found, using dummy regulator [ 11.917174] axp20x-rsb sunxi-rsb-3a3: AXP20x variant AXP803 found
Despite being loaded as a very early module, PMIC init ^^^ only starts now.
[ 11.928664] hub 1-0:1.0: 1 port detected [ 11.943230] anx6345 0-0038: 0-0038 supply dvdd25-supply not found, using dummy regulator
So far, so bad, but lucky me has an U-Boot which already enabled the display along with the relevant voltages in the proper sequence.
[ 11.981316] [drm] Found ANX6345 (ver. 170) eDP Transmitter
But much later on
[ 38.248573] dcdc4: disabling [ 38.268493] vcc-pd: disabling [ 38.288446] vdd-edp: disabling
screen goes dark and stays dark. Use count of the regulators is 0. I guess this is because the driver code had been returned the dummy instead?
It's a mobile device so in principle there is nothing wrong with powering down unused circuitry, and always-on is not an option. Am I correct to perceive this solution as not 100% mature yet? The anx6345 driver in particular needs to do a little "voltage dance" with specific timing on the real regulators should the device come up really unpowered, so IMHO it's probably neccessary to return EPROBE_DEFER at least in this particular case and prepare the driver for it? Or what would be the real solution in this case?
Torsten