Re: [PATCH v2] arm64: dts: rockchip: rk356x: Fix PCIe register map and ranges

[Peter Geis]

On Wed, Oct 5, 2022 at 4:54 AM Ondrej Jirman <megi@xxxxxx> wrote:
>

Good Morning,

> I have two Realtek PCIe wifi cards connected over the 4 port PCIe swtich
> to Quartz64-A. The cards fail to work, when nvme SSD is connected at the
> same time to the bridge. Without nvme connected, cards work fine. The
> issue seems to be related to mixed use of devices which make use of I/O
> ranges and memory ranges.
>
> This patch changes I/O, MEM and config mappings so that config and I/O
> mappings use the 0xf4000000 outbound address space, and MEM range uses
> the whole 0x300000000 outbound space.
>
> This is simialar to how BSP does the mappings.

This change was very recent in the BSP stuff (Jan 2022):
https://github.com/rockchip-linux/kernel/commit/cfab7abefc4093daa379fbd90a1e7ac1a484332b
A few other interesting changes there as well. They added a 32 bit
window in the lower range and made the entire upper range a 64 bit
relocatable (why?) and prefetchable window. They also set the viewport
number to 8. The dt-binding says this is autodetected, but I wonder if
the value is being detected correctly.

It looks like it is dependent in BSP on a backported change from mainline:
https://github.com/rockchip-linux/kernel/commit/50a01d3c10a6212f66364575a3c8f66c07f41591

Can someone weigh in why the dw core has config in the reg node
instead of ranges?

>
> I changed num-ob-windows to value detected by the kernel so if for whatever
> reason the kernel ever starts respecting this DT property, it would not
> switch to sharing I/O and CFG spaces via a single iATU mapping for
> no reason.

This worries me that this value may be being detected incorrectly,
they set it to this for a reason. It's not unheard of for Rockchip to
need to override what they encode in the silicon.

Very Respectfully,
Peter Geis

>
> This change to the regs/ranges makes the issue go away and both nvme and
> wifi cards work when connected at the same time to the bridge. I tested
> the nvme with large amount of reads/writes, both behind the PCIe bridge
> and when directly connected to Quartz64-A board.
>
> Signed-off-by: Ondrej Jirman <megi@xxxxxx>
> ---
> BSP for reference: https://github.com/rockchip-linux/kernel/blob/develop-4.19/arch/arm64/boot/dts/rockchip/rk3568.dtsi#L2370
>
> v2:
> - change ranges to use 0x300000000 fully for MEM and make use of
>   the 0xf4000000 outbound range for IO and config
> - full retest with/without the switch
> - if lscpi/dmesg is useful in the future for comparison, see:
>   https://xff.cz/kernels/random/quartz64a-pcie/
>
> I used this script for the tests:
>
> #!/bin/bash
>
> OUT=/mnt/data
> n=8
>
> test -f /tmp/test.dat || \
>     dd if=/dev/urandom of=/tmp/test.dat bs=1M count=1024
> md5sum /tmp/test.dat
>
> i=0
> while test $i -lt $n
> do
>     dd if=/tmp/test.dat of=$OUT/test$i.dat bs=4M oflag=direct
>
>     i=$(($i+1))
> done
>
> i=0
> while test $i -lt $n
> do
>     dd if=$OUT/test$i.dat bs=4M iflag=direct | md5sum
>
>     i=$(($i+1))
> done
>
>
>  arch/arm64/boot/dts/rockchip/rk356x.dtsi | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/boot/dts/rockchip/rk356x.dtsi b/arch/arm64/boot/dts/rockchip/rk356x.dtsi
> index 319981c3e9f7..99fd9543fc6f 100644
> --- a/arch/arm64/boot/dts/rockchip/rk356x.dtsi
> +++ b/arch/arm64/boot/dts/rockchip/rk356x.dtsi
> @@ -855,7 +855,8 @@ pcie2x1: pcie@fe260000 {
>                 compatible = "rockchip,rk3568-pcie";
>                 reg = <0x3 0xc0000000 0x0 0x00400000>,
>                       <0x0 0xfe260000 0x0 0x00010000>,
> -                     <0x3 0x3f000000 0x0 0x01000000>;
> +                     <0x0 0xf4000000 0x0 0x01f00000>;
> +
>                 reg-names = "dbi", "apb", "config";
>                 interrupts = <GIC_SPI 75 IRQ_TYPE_LEVEL_HIGH>,
>                              <GIC_SPI 74 IRQ_TYPE_LEVEL_HIGH>,
> @@ -877,15 +878,15 @@ pcie2x1: pcie@fe260000 {
>                                 <0 0 0 4 &pcie_intc 3>;
>                 linux,pci-domain = <0>;
>                 num-ib-windows = <6>;
> -               num-ob-windows = <2>;
> +               num-ob-windows = <8>;
>                 max-link-speed = <2>;
>                 msi-map = <0x0 &gic 0x0 0x1000>;
>                 num-lanes = <1>;
>                 phys = <&combphy2 PHY_TYPE_PCIE>;
>                 phy-names = "pcie-phy";
>                 power-domains = <&power RK3568_PD_PIPE>;
> -               ranges = <0x01000000 0x0 0x3ef00000 0x3 0x3ef00000 0x0 0x00100000
> -                         0x02000000 0x0 0x00000000 0x3 0x00000000 0x0 0x3ef00000>;
> +               ranges = <0x01000000 0x0 0x00000000 0x0 0xf5f00000 0x0 0x00100000
> +                         0x02000000 0x0 0x40000000 0x3 0x00000000 0x0 0x40000000>;
>                 resets = <&cru SRST_PCIE20_POWERUP>;
>                 reset-names = "pipe";
>                 #address-cells = <3>;
> --
> 2.37.3
>