Re: [PATCH v2] arm64: dts: rockchip: add attiny_rst_gate to Ringneck

From: Quentin Schulz
Date: Fri Sep 27 2024 - 05:51:03 EST


Hi Heiko,

On 9/27/24 11:39 AM, Heiko Stuebner wrote:
Am Donnerstag, 26. September 2024, 15:24:03 CEST schrieb Quentin Schulz:
Hi Jakob,

On 9/26/24 3:20 PM, Jakob Unterwurzacher wrote:
Ringneck v1.4 can contain (placement option) an on-board ATtiny
microcontroller instead of an STM32. In normal operation, this
is transparent to the software, as both microcontrollers emulate
the same ICs (amc6821 and isl1208).

For flashing the ATtiny, the SWITCH_REG1 regulator of the board's PMIC is
used to enable the ATtiny UPDI debug interface. If the STM32 is placed, or if
we are running on an older Ringneck revision, SWITCH_REG1 is not connected
and has no effect.

Add attiny-updi-gate-regulator so userspace can control it via sysfs
(needs CONFIG_REGULATOR_USERSPACE_CONSUMER):

echo enabled > /sys/devices/platform/attiny-updi-gate-regulator/state

Signed-off-by: Jakob Unterwurzacher <jakob.unterwurzacher@xxxxxxxxx>
Tested-by: Quentin Schulz <quentin.schulz@xxxxxxxxx>

Reviewed-by: Quentin Schulz <quentin.schulz@xxxxxxxxx>

This is a candidate for backporting to stable branches as well I assume,
@Heiko?

That is more on the darker side of gray here.

Looking at the stable-kernel-rules [0] the criteria is
"It must either fix a real bug that bothers people or just add a device ID"

This change instead is adding a new feature to allow said flashing from a
running system.


This does mean that the new version of the device won't work as well with an older kernel though.

I thought the rules for DT backporting were a bit more permissive than for drivers. Maybe because most of the DT patches I posted were actual fixes :)

Up to you!

Cheers,
Quentin