linux-kernel - Re: Re: [PATCH] arm64: dts: rockchip: remove startup-delay-us from vcc3v3

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Date: Wed,  3 Apr 2024 15:59:16 +0800
From: Jianfeng Liu <liujianfeng1994@...il.com>
To: heiko@...ech.de
Cc: conor+dt@...nel.org,
	devicetree@...r.kernel.org,
	krzysztof.kozlowski+dt@...aro.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-rockchip@...ts.infradead.org,
	liujianfeng1994@...il.com,
	robh@...nel.org,
	sfr@...b.auug.org.au
Subject: Re: Re: [PATCH] arm64: dts: rockchip: remove startup-delay-us from vcc3v3_pcie2x1l0 on rock-5b

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@...70000 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