Re: [BUG] rockpro64: PCI BAR reassignment broken by commit 9d57e61bf723 ("of/pci: Add IORESOURCE_MEM_64 to resource flags for 64-bit memory addresses")

From: Anand Moon
Date: Tue May 25 2021 - 12:59:39 EST

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Hi Ard,

On Tue, 25 May 2021 at 19:27, Ard Biesheuvel <ardb@xxxxxxxxxx> wrote:
>
> On Tue, 25 May 2021 at 15:42, Punit Agrawal <punitagrawal@xxxxxxxxx> wrote:
> >
> > Hi Ard,
> >
> > Ard Biesheuvel <ardb@xxxxxxxxxx> writes:
> >
> > > On Sun, 23 May 2021 at 13:06, Punit Agrawal <punitagrawal@xxxxxxxxx> wrote:
> > >>
> > >> Robin Murphy <robin.murphy@xxxxxxx> 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@xxxxxxxxxxxxxx/

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

Best Regards
-Anand

>
> > I am happy to put something together once I understand the preferred way
> > to go about it.
> >
> > Thanks,
> > Punit
> >
> > [...]
> >
>
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