From: Simon Glass sjg@chromium.org Date: Sat, 22 Jan 2022 10:17:10 -0700
Hi Simon,
Hi Mark,
On Sat, 22 Jan 2022 at 07:12, Mark Kettenis mark.kettenis@xs4all.nl wrote:
From: Simon Glass sjg@chromium.org Date: Fri, 21 Jan 2022 18:40:23 -0700
Hi Mark,
On Fri, 14 Jan 2022 at 04:05, Mark Kettenis kettenis@openbsd.org wrote:
The power management controller found on Apple SoCs als provides a way to reset all devices within a power domain. This is needed to cleanly shutdown the NVMe controller before we hand over control to the OS.
Signed-off-by: Mark Kettenis kettenis@openbsd.org
arch/arm/Kconfig | 1 + drivers/power/domain/apple-pmgr.c | 73 ++++++++++++++++++++++++++++++- 2 files changed, 73 insertions(+), 1 deletion(-)
This should use devicetree instead of device_bind() and be a reset driver in drivers/reset
Not sure what you mean with "this should use devicetree". The reset and power domain functionality is integrated in the same hardware register and there is a single node that decsribes the device.
The Linux driver implements the power domain and reset functionality in a single driver as well. I suppose I could move the reset code into a file of its own in drivers/reset, but I don't think it would make the code easier to understand. And I'd still need to bind the reset driver explicitly in apple_pmgr_probe() as it isn't possible to automatically bind two drivers to a single device tree node as far as I can tell.
It seems odd that Linux does this sort of thing. The normal U-Boot approach would be to create a parent MFD driver with children for each uclass. Does linux do that these days?
It seems to be common for pinctrl/gpio and clk/reset drivers to be combined in Linux. Not sure if there was a pd/reset combo before the M1 support was accepted, but it is there.
MFD is typically used for higher-level functions, i.e. PMIC IC's that include both voltage regulators and an RTC for example.
Driver model cannot create two drivers from one device tree node, although you can create one manually later as you have done.
It seems OK to follow along with Linux, if it makes it easier to maintain. Otherwise, drivers/reset would be better for the reset driver.
Either way:
Reviewed-by: Simon Glass sjg@chromium.org Tested on: Macbook Air M1 Tested-by: Simon Glass sjg@chromium.org
I'll keep it as-is then.
Thanks,
Mark