Date:   Thu, 09 Jun 2022 11:41:43 +0200
From:   Martin Kepplinger <martin.kepplinger@...i.sm>
To:     Lucas Stach <l.stach@...gutronix.de>,
        Adam Ford <aford173@...il.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>, peng.fan@....com,
        festevam@...il.com, lgirdwood@...il.com
Cc:     linux-media <linux-media@...r.kernel.org>,
        NXP Linux Team <linux-imx@....com>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        kernel@...i.sm
Subject: soc: imx: gpcv2: regulator issue with system suspend on imx8mq

hi Lucas and all interested in suspend to ram on imx8mq,

This is slighly repeating my previous observations that still apply,
but summarizing the situation:

s2idle should work on mainline when looking at the implementations of
platform drivers. With the missing bits
https://source.codeaurora.org/external/imx/linux-imx/commit/?h=imx_5.10.35_2.0.0_imx8ulp_er&id=ab850d655c22df562c27c9d6775a26b6df6865b5
and
https://lore.kernel.org/linux-arm-kernel/1631554694-9599-7-git-send-email-abel.vesa@nxp.com/
suspend to ram should work too,
and it does for me, except when a power domain is using a board-
regulator as power-supply that is not always-on, but controlled by a
driver. (when I describe these as "always-on", things are fine (except
for unrelated edgecases)) here's the example I'm running where I don't
describe "buck3" as always-on, but etnaviv runtime pm is controlling
it:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi#n1161
When starting to resume, the following happens:

[  139.985440] Enabling non-boot CPUs ...
[  139.990363] Detected VIPT I-cache on CPU1
[  139.990413] GICv3: CPU1: found redistributor 1 region
0:0x00000000388a0000
[  139.990487] CPU1: Booted secondary processor 0x0000000001
[0x410fd034]
[  139.991445] CPU1 is up
[  140.011836] Detected VIPT I-cache on CPU2
[  140.011852] GICv3: CPU2: found redistributor 2 region
0:0x00000000388c0000
[  140.011876] CPU2: Booted secondary processor 0x0000000002
[0x410fd034]
[  140.012284] CPU2 is up
[  140.032739] Detected VIPT I-cache on CPU3
[  140.032756] GICv3: CPU3: found redistributor 3 region
0:0x00000000388e0000
[  140.032780] CPU3: Booted secondary processor 0x0000000003
[0x410fd034]
[  140.033310] CPU3 is up
[  140.158791] imx-pgc imx-pgc-domain.5: failed to enable regulator: -
110

trying runtime-resume in system-suspend for i2c busses didn't help me
here for example. What's your idea for solving this? (regulator always-
on is not an acceptable workaround :) I'm always happy to test concrete
ideas and would like to know from anyone who uses system suspend on
imx8mq.

history
-------
last time this came to my attention via the mainling lists was the VPU
addition:
https://lore.kernel.org/linux-arm-kernel/8ed3a28d59b442b531e68e95d83b187bb3392940.camel@puri.sm/
but for the above logs and all current tests, I ignore the VPU (set the
power-supply always-on) simply because the the driver is in staging and
seems to create a different problem when suspending, and the GPU power-
supply example is very well suited to highlight the problem.

but before that, "gpcv2: support systemd suspend/resume"
( https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=da4112230f86
) didn't work for me, see:
https://lore.kernel.org/all/a20ecd639f8e8b7fa4a9bed7a8e9590225262784.camel@puri.sm/

thanks a lot,

                               martin

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