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Subject: Re: [BUG] rockpro64: PCI BAR reassignment broken by commit
 9d57e61bf723 ("of/pci: Add IORESOURCE_MEM_64 to resource flags for 64-bit
 memory addresses")
To:     Anand Moon <linux.amoon@gmail.com>,
        Ard Biesheuvel <ardb@kernel.org>
Cc:     Punit Agrawal <punitagrawal@gmail.com>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-rockchip@lists.infradead.org,
        arm-mail-list <linux-arm-kernel@lists.infradead.org>,
        Heiko Stuebner <heiko.stuebner@theobroma-systems.com>,
        leobras.c@gmail.com, Rob Herring <robh@kernel.org>,
        PCI <linux-pci@vger.kernel.org>
References: <7a1e2ebc-f7d8-8431-d844-41a9c36a8911@arm.com>
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 <CAMj1kXE3U+16A6bO0UHG8=sx45DE6u0FtdSnoLDvfGnFJYTDrg@mail.gmail.com>
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 <CAMj1kXFk2u=tbTYpa6Vqz5ihATFq61pCDiEbfRgXL_Rw+q_9Fg@mail.gmail.com>
 <CANAwSgQEti7=dsYbqYMxrcP9KPFc-s0e4xHPPwOC=gP+scpP3w@mail.gmail.com>
From:   Robin Murphy <robin.murphy@arm.com>
Message-ID: <4292e929-779f-9c83-f75c-7d8121a1c6c8@arm.com>
Date:   Tue, 25 May 2021 18:14:42 +0100
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On 2021-05-25 17:59, Anand Moon wrote:
> Hi Ard,
> 
> On Tue, 25 May 2021 at 19:27, Ard Biesheuvel <ardb@kernel.org> wrote:
>>
>> On Tue, 25 May 2021 at 15:42, Punit Agrawal <punitagrawal@gmail.com> wrote:
>>>
>>> Hi Ard,
>>>
>>> Ard Biesheuvel <ardb@kernel.org> writes:
>>>
>>>> On Sun, 23 May 2021 at 13:06, Punit Agrawal <punitagrawal@gmail.com> wrote:
>>>>>
>>>>> Robin Murphy <robin.murphy@arm.com> writes:
>>>>>
>>>>>> [ +linux-pci for visibility ]
>>>>>>
>>>>>> On 2021-05-18 10:09, Alexandru Elisei wrote:
>>>>>>> After doing a git bisect I was able to trace the following error when booting my
>>>>>>> rockpro64 v2 (rk3399 SoC) with a PCIE NVME expansion card:
>>>>>>> [..]
>>>>>>> [    0.305183] rockchip-pcie f8000000.pcie: host bridge /pcie@f8000000 ranges:
>>>>>>> [    0.305248] rockchip-pcie f8000000.pcie:      MEM 0x00fa000000..0x00fbdfffff ->
>>>>>>> 0x00fa000000
>>>>>>> [    0.305285] rockchip-pcie f8000000.pcie:       IO 0x00fbe00000..0x00fbefffff ->
>>>>>>> 0x00fbe00000
>>>>>>> [    0.306201] rockchip-pcie f8000000.pcie: supply vpcie1v8 not found, using dummy
>>>>>>> regulator
>>>>>>> [    0.306334] rockchip-pcie f8000000.pcie: supply vpcie0v9 not found, using dummy
>>>>>>> regulator
>>>>>>> [    0.373705] rockchip-pcie f8000000.pcie: PCI host bridge to bus 0000:00
>>>>>>> [    0.373730] pci_bus 0000:00: root bus resource [bus 00-1f]
>>>>>>> [    0.373751] pci_bus 0000:00: root bus resource [mem 0xfa000000-0xfbdfffff 64bit]
>>>>>>> [    0.373777] pci_bus 0000:00: root bus resource [io  0x0000-0xfffff] (bus
>>>>>>> address [0xfbe00000-0xfbefffff])
>>>>>>> [    0.373839] pci 0000:00:00.0: [1d87:0100] type 01 class 0x060400
>>>>>>> [    0.373973] pci 0000:00:00.0: supports D1
>>>>>>> [    0.373992] pci 0000:00:00.0: PME# supported from D0 D1 D3hot
>>>>>>> [    0.378518] pci 0000:00:00.0: bridge configuration invalid ([bus 00-00]),
>>>>>>> reconfiguring
>>>>>>> [    0.378765] pci 0000:01:00.0: [144d:a808] type 00 class 0x010802
>>>>>>> [    0.378869] pci 0000:01:00.0: reg 0x10: [mem 0x00000000-0x00003fff 64bit]
>>>>>>> [    0.379051] pci 0000:01:00.0: Max Payload Size set to 256 (was 128, max 256)
>>>>>>> [    0.379661] pci 0000:01:00.0: 8.000 Gb/s available PCIe bandwidth, limited by
>>>>>>> 2.5 GT/s PCIe x4 link at 0000:00:00.0 (capable of 31.504 Gb/s with 8.0 GT/s PCIe
>>>>>>> x4 link)
>>>>>>> [    0.393269] pci_bus 0000:01: busn_res: [bus 01-1f] end is updated to 01
>>>>>>> [    0.393311] pci 0000:00:00.0: BAR 14: no space for [mem size 0x00100000]
>>>>>>> [    0.393333] pci 0000:00:00.0: BAR 14: failed to assign [mem size 0x00100000]
>>>>>>> [    0.393356] pci 0000:01:00.0: BAR 0: no space for [mem size 0x00004000 64bit]
>>>>>>> [    0.393375] pci 0000:01:00.0: BAR 0: failed to assign [mem size 0x00004000 64bit]
>>>>>>> [    0.393397] pci 0000:00:00.0: PCI bridge to [bus 01]
>>>>>>> [    0.393839] pcieport 0000:00:00.0: PME: Signaling with IRQ 78
>>>>>>> [    0.394165] pcieport 0000:00:00.0: AER: enabled with IRQ 78
>>>>>>> [..]
>>>>>>> to the commit 9d57e61bf723 ("of/pci: Add IORESOURCE_MEM_64 to
>>>>>>> resource flags for
>>>>>>> 64-bit memory addresses").
>>>>>>
>>>>>> FWFW, my hunch is that the host bridge advertising no 32-bit memory
>>>>>> resource, only only a single 64-bit non-prefetchable one (even though
>>>>>> it's entirely below 4GB) might be a bit weird and tripping something
>>>>>> up in the resource assignment code. It certainly seems like the thing
>>>>>> most directly related to the offending commit.
>>>>>>
>>>>>> I'd be tempted to try fiddling with that in the DT (i.e. changing
>>>>>> 0x83000000 to 0x82000000 in the PCIe node's "ranges" property) to see
>>>>>> if it makes any difference. Note that even if it helps, though, I
>>>>>> don't know whether that's the correct fix or just a bodge around a
>>>>>> corner-case bug somewhere in the resource code.
>>>>>
>>>>>  From digging into this further the failure seems to be due to a mismatch
>>>>> of flags when allocating resources in pci_bus_alloc_from_region() -
>>>>>
>>>>>      if ((res->flags ^ r->flags) & type_mask)
>>>>>              continue;
>>>>>
>>>>> Though I am also not sure why the failure is only being reported on
>>>>> RK3399 - does a single 64-bit window have anything to do with it?
>>>>>
>>>>
>>>> The NVMe in the example exposes a single 64-bit non-prefetchable BAR.
>>>> Such BARs can not be allocated in a prefetchable host bridge window
>>>> (unlike the converse, i.e., allocating a prefetchable BAR in a
>>>> non-prefetchable host bridge window is fine)
>>>>
>>>> 64-bit non-prefetchable host bridge windows cannot be forwarded by PCI
>>>> to PCI bridges, they simply lack the BAR registers to describe them.
>>>> Therefore, non-prefetchable endpoint BARs (even 64-bit ones) need to
>>>> be carved out of a host bridge's non-prefetchable 32-bit window if
>>>> they need to pass through a bridge.
>>>
>>> Thank you for the explanation. I also looked at the PCI-to-PCI Bridge
>>> spec to understand where some of the limitations are coming from.
>>>
>>>> So the error seems to be here that the host bridge's 32-bit
>>>> non-prefetchable window has the 64-bit attribute set, even though it
>>>> resides below 4 GB entirely. I suppose that the resource allocation
>>>> could be made more forgiving (and it was in the past, before commit
>>>> 9d57e61bf723 was applied). However, I would strongly recommend not
>>>> deviating from common practice, and just describe the 32-bit
>>>> addressable non-prefetchable resource window as such.
>>>
>>> IIUC, the host bridge's configuration (64-bit on non-prefetchable
>>> window) is based on what the hardware advertises.
>>>
>>
>> What do you mean by 'what the hardware advertises'? The host bridge is
>> apparently configured to decode a 32-bit addressable window as MMIO,
>> and the question is why this window has the 64-bit attribute set in
>> the DT description.
>>
>>> Can you elaborate on what you have in mind to correct the
>>> non-prefetchable resource window? Are you thinking of adding a quirk
>>> somewhere to address this?
>>>
>>
>> No. Just fix the DT.
> 
> Yes DTS changes are needed as well as some more core driver changes.
> 
> As per the Rk3399 TRM (Rockchip RK3399 TRM V1.3 Part2.pdf)
> [0] https://rockchip.fr/Rockchip%20RK3399%20TRM%20V1.3%20Part2.pdf
> 
> I had made the following dts changes relates to ranges as per PCI below.
> 
> *17.6.1 Internal Register Address Mapping
>     Table 17-23 Global Address Map for Core Local Management*
> 
> diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> index 634a91af8e83..796b44e07be1 100644
> --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
> @@ -199,7 +199,7 @@ xin24m: xin24m {
> 
>          pcie0: pcie@f8000000 {
>                  compatible = "rockchip,rk3399-pcie";
> -               reg = <0x0 0xf8000000 0x0 0x2000000>,
> +               reg = <0x0 0xf8000000 0x0 0x6000000>,
>                        <0x0 0xfd000000 0x0 0x1000000>;
>                  reg-names = "axi-base", "apb-base";
>                  device_type = "pci";
> @@ -227,8 +227,8 @@ pcie0: pcie@f8000000 {
>                         <&pcie_phy 2>, <&pcie_phy 3>;
>                  phy-names = "pcie-phy-0", "pcie-phy-1",
>                              "pcie-phy-2", "pcie-phy-3";
> -               ranges = <0x83000000 0x0 0xfa000000 0x0 0xfa000000 0x0
> 0x1e00000>,
> -                        <0x81000000 0x0 0xfbe00000 0x0 0xfbe00000 0x0
> 0x100000>;
> +               ranges = <0x83000000 0x0 0xfd800000 0x0 0xfd810000 0x0
> 0x100000>,
> +                        <0x81000000 0x0 0xfd800000 0x0 0xfda00000 0x0
> 0x100000>;
>                  resets = <&cru SRST_PCIE_CORE>, <&cru SRST_PCIE_MGMT>,
>                           <&cru SRST_PCIE_MGMT_STICKY>, <&cru SRST_PCIE_PIPE>,
>                           <&cru SRST_PCIE_PM>, <&cru SRST_P_PCIE>,
> @@ -2040,6 +2040,21 @@ pcfg_pull_up_2ma: pcfg-pull-up-2ma {
>                          drive-strength = <2>;
> 
> Also, the BAR configuration is missing some tuning bits missing,
> *   17.6.7.1.45 Root Complex BAR Configuration Register.*
> 
> Earlier I had to face this issue on my Rk3399 board (Odroid n1), but I
> could not resolve the issue.
> 
> [1] https://patchwork.kernel.org/project/linux-rockchip/patch/1590023130-137406-1-git-send-email-shawn.lin@rock-chips.com/
> 
> How can I debug the PCIe handshake messages to explore further?
> 
> [alarm@alarm ~]$ dmesg | grep pci
> [    1.399919] ehci-pci: EHCI PCI platform driver
> [    1.538434] ohci-pci: OHCI PCI platform driver
> [    7.112556] rockchip-pcie f8000000.pcie: host bridge /pcie@f8000000 ranges:
> [    7.120583] rockchip-pcie f8000000.pcie: Parsing ranges property...
> [    7.134628] rockchip-pcie f8000000.pcie:      MEM
> 0x00fd810000..0x00fd90ffff -> 0x00fd800000
> [    7.144148] rockchip-pcie f8000000.pcie:       IO
> 0x00fda00000..0x00fdafffff -> 0x00fd800000
> [    7.165435] rockchip-pcie f8000000.pcie: can't request region for
> resource [mem 0xf8000000-0xfdffffff]
> [    7.182904] rockchip-pcie: probe of f8000000.pcie failed with error -16

Sorry, you've changed your DT for unknown reasons to put the memory and 
I/O windows at the same bus address, and now you want help debugging why 
trying to put two things at the same address gives -EBUSY?

:/

Is it Friday already?

Robin.