imx8mp: pci enumeration fails with current HEAD

[Heiko Schocher]

Hello Miquel,

On 17.04.25 16:37, Heiko Schocher wrote:
> 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

okay, the "power_domain=00000000fe594458" for the IMX8MP_HSIOBLK_PD_PCIE case
is different as the one for the IMX8MP_HSIOBLK_PD_PCIE_PHY case ... so priv pointer
should also be different... so that should be fine ... I do not see any debug output
where this "power_domain=00000000fe594458" gets enabled (or disabled before) ... I
have to debug deeper into it... sorry. But may you have an idea...

bye,
Heiko
> 
> 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

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