imx8mp: pci enumeration fails with current HEAD

[Heiko Schocher]

Hi Miquel,

I have here an imx8mp based board for which I just prepare mainlining.

pci enumeration works fine with U-Boot 2025.04

u-boot=> pci enum
PCIE-0: Link up (Gen1-x1, Bus0)
u-boot=>

and tftp through the ethernet interface works fine.

Using current HEAD

* 5b4ae0f3f04 - (origin/master, origin/HEAD) mailmap: update my name and email (vor 2 Tagen) <Casey 
Connolly>

It breaks with:

u-boot=> pci enum
nxp_imx8_pcie_phy pcie-phy at 32f00000: PHY: Failed to power on pcie-phy at 32f00000: -110.
pcie_dw_imx pcie at 33800000: failed to power on PHY
u-boot=>

git bisect dropped your patch:

197376fbf300e92afa0a1583815d9c9eb52d613a is the first bad commit
commit 197376fbf300e92afa0a1583815d9c9eb52d613a
Author: Miquel Raynal <miquel.raynal at bootlin.com>
Date:   Thu Apr 3 09:39:05 2025 +0200

     power-domain: Add refcounting

     It is very surprising that such an uclass, specifically designed to
     handle resources that may be shared by different devices, is not keeping
     the count of the number of times a power domain has been
     enabled/disabled to avoid shutting it down unexpectedly or disabling it
     several times.

     Doing this causes troubles on eg. i.MX8MP because disabling power
     domains can be done in recursive loops were the same power domain
     disabled up to 4 times in a row. PGCs seem to have tight FSM internal
     timings to respect and it is easy to produce a race condition that puts
     the power domains in an unstable state, leading to ADB400 errors and
     later crashes in Linux.

     CI tests using power domains are slightly updated to make sure the count
     of on/off calls is even and the results match what we *now* expect.

     As we do not want to break existing users while stile getting
     interesting error codes, the implementation is split between:
     - a low-level helper reporting error codes if the requested transition
       could not be operated,
     - a higher-level helper ignoring the "non error" codes, like EALREADY and
       EBUSY.

     Signed-off-by: Miquel Raynal <miquel.raynal at bootlin.com>


reverting this patch, and it works again fine for me!

Do you have a imx8mp based hardware with pci?

Can you (or anyone else with an imx8mp based hardware with pci) approve
this on a similiar HW?

I try to dig into it, but may you have a fast idea!

Okay, thought about it ... it tries to power on "blk-ctrl at 32f10000"
driver:/drivers/power/domain/imx8mp-hsiomix.c

imx8mp.dtsi:
                         hsio_blk_ctrl: blk-ctrl at 32f10000 {
                                 compatible = "fsl,imx8mp-hsio-blk-ctrl", "syscon";

which has several different power domains ... and your patch prevents to
enable more than one of them ... adding some debugs shows:

u-boot=> pci enum
[...]
power_domain_on_lowlevel(power_domain=00000000fe5942f8) blk-ctrl at 32f10000 priv->on_count: 0
power_domain_on_lowlevel(power_domain=00000000fe5942f8) blk-ctrl at 32f10000 power_domain->id: 4

Here pwoer domain id

#define IMX8MP_HSIOBLK_PD_PCIE_PHY                      4

gets enabled and on_count increases...

imx8mp_hsiomix_set: ------------ power_domain->id: 4 IMX8MP_HSIOBLK_PD_PCIE: 3 4
power_domain_on_lowlevel(power_domain=00000000fe5d2408) power-domain at 17 priv->on_count: 0
power_domain_on_lowlevel(power_domain=00000000fe5d2408) power-domain at 17 power_domain->id: 0
power_domain_on_lowlevel: ret: 0
power_domain_on_lowlevel(power_domain=00000000fe5d2480) power-domain at 1 priv->on_count: 0
power_domain_on_lowlevel(power_domain=00000000fe5d2480) power-domain at 1 power_domain->id: 0
power_domain_on_lowlevel: ret: 0
imx8mp_hsiomix_set: ------------ power_domain->id: 4 IMX8MP_HSIOBLK_PD_PCIE: 3 4 END OKAY
power_domain_on_lowlevel: ret: 0
power_domain_get_by_index(dev=00000000fe5b2410, power_domain=00000000fe594458)
power_domain_on_lowlevel(power_domain=00000000fe594458) blk-ctrl at 32f10000 priv->on_count: 1
power_domain_on_lowlevel(power_domain=00000000fe594458) blk-ctrl at 32f10000 power_domain->id: 3

Now power domain

#define IMX8MP_HSIOBLK_PD_PCIE                          3

should be enabled, but since your patch this gets prevented as "priv->on_count: 1"

imx8_pcie_phy_power_on: ------------ pad_mode: 1
imx8_pcie_phy_power_on: ------------ pad_mode: 1 ret: -110
nxp_imx8_pcie_phy pcie-phy at 32f00000: PHY: Failed to power on pcie-phy at 32f00000: -110.
pcie_dw_imx pcie at 33800000: failed to power on PHY
u-boot=>

I have not a fast solution, may you have an idea? I try to look
after the easter holidays into it. May we need for each power_domain-> id such
an on counter...

Thanks!

bye,
Heiko
-- 
DENX Software Engineering GmbH,      Managing Director: Erika Unter
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-52   Fax: +49-8142-66989-80   Email: hs at denx.de