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From: Jianfeng Liu <liujianfeng1994@gmail.com>
To: heiko@sntech.de
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Subject: Re: Re: [PATCH] arm64: dts: rockchip: remove startup-delay-us from vcc3v3_pcie2x1l0 on rock-5b
Date: Wed,  3 Apr 2024 15:59:16 +0800
Message-Id: <20240403075916.1025550-1-liujianfeng1994@gmail.com>
In-Reply-To: <2535182.Sgy9Pd6rRy@diego>
References: <2535182.Sgy9Pd6rRy@diego>
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Hi Heiko,

Tue, 02 Apr 2024 12:39:17 +0200, Heiko Stübner wrote:
>Does the pcie driver enable the regulator too late somehow?
The pcie driver will enable the regulator imediately when it is probed.
I added log at when driver is probed and when regulator is enabled.
Here is the log with "startup-delay-us = <50000>":
```
[    1.572991] rockchip-dw-pcie a40800000.pcie: rockchip_pcie_probe start
[    1.573697] rockchip-dw-pcie a40800000.pcie: going to enable vpcie3v3 regulator
[    1.575194] rockchip-dw-pcie a40800000.pcie: enable vpcie3v3 regulator done
```

And here is the log without "startup-delay-us":
```
[    1.518490] rockchip-dw-pcie a40800000.pcie: rockchip_pcie_probe start
[    1.518603] rockchip-dw-pcie a40800000.pcie: going to enable vpcie3v3 regulator
[    1.518610] rockchip-dw-pcie a40800000.pcie: enable vpcie3v3 regulator done
```

We can see startup-delay-us will delay the driver probe.

I also take a look at rockchip's SDK kernel, their pci driver is probed
very late:
```
[    3.398682] dw-pcie fe170000.pcie: invalid resource
[    3.398686] dw-pcie fe170000.pcie: Failed to initialize host
[    3.398688] dw-pcie: probe of fe170000.pcie failed with error -22
[    3.399396] rk-pcie fe170000.pcie: invalid prsnt-gpios property in node
[    3.399410] rk-pcie fe170000.pcie: Looking up vpcie3v3-supply from device tree
[    3.405195] rk-pcie fe170000.pcie: host bridge /pcie@fe170000 ranges:
[    3.405253] rk-pcie fe170000.pcie:       IO 0x00f2100000..0x00f21fffff -> 0x00f2100000
[    3.405283] rk-pcie fe170000.pcie:      MEM 0x00f2200000..0x00f2ffffff -> 0x00f2200000
[    3.405310] rk-pcie fe170000.pcie:      MEM 0x0980000000..0x09bfffffff -> 0x0980000000
[    3.405372] rk-pcie fe170000.pcie: iATU unroll: enabled
[    3.405381] rk-pcie fe170000.pcie: iATU regions: 8 ob, 8 ib, align 64K, limit 8G
[    3.666917] rk-pcie fe170000.pcie: PCIe Link up, LTSSM is 0x30011
[    3.666932] rk-pcie fe170000.pcie: PCIe Gen.1 x1 link up
[    3.667139] rk-pcie fe170000.pcie: PCI host bridge to bus 0002:20
```

And it is reported that startup-delay-us is necessary in rockchip's SDK
kernel. But in mainline kernel it is different.

Jianfeng