[PATCH] pci: layerscape: Fix spurious writes and panic

[Vladimir Oltean]

Hi Michael,

On Tue, Aug 04, 2020 at 12:16:33AM +0200, Michael Walle wrote:
> The fdt_fixup_pcie_ls() scans all PCI devices and assumes that all PCI
> root devices are layerscape PCIe controllers. Unfortunately, this is not
> true for the LS1028A. There is one additional static PCI root complex
> (this contains the networking devices) which has nothing to do with the
> layerscape PCIe controllers. On recent U-Boot versions this results in
> the following panic:
> 
> "Synchronous Abort" handler, esr 0x96000044
> elr: 000000009602fa04 lr : 000000009602f9f4 (reloc)
> elr: 00000000fbd73a04 lr : 00000000fbd739f4
> x0 : 0080000002000101 x1 : 0000000000000000
> x2 : 00000000fbde9000 x3 : 0000000000000001
> x4 : 0000000000000000 x5 : 0000000000000030
> x6 : 00000000fbdbd460 x7 : 00000000fbb3d3a0
> x8 : 0000000000000002 x9 : 000000000000000c
> x10: 00000000ffffffe8 x11: 0000000000000006
> x12: 000000000001869f x13: 0000000000000a2c
> x14: 00000000fbb3d2cc x15: 00000000ffffffff
> x16: 0000000000010000 x17: 0000000000000000
> x18: 00000000fbb3fda0 x19: 0000000000000800
> x20: 0000000000000000 x21: 00000001f0000000
> x22: 0000000000000800 x23: 0000000000000009
> x24: 00000000fbdc3c1b x25: 00000000fbdc28e5
> x26: 00000000fbdcc008 x27: 00000000fbdc16e2
> x28: 000000000f000000 x29: 00000000fbb3d3a0
> 
> Code: 394072a1 f94006a0 34000041 5ac00a94 (b8336814)
> Resetting CPU ...
> 
> This bug already existed in former versions, but the spurious write was
> never trapped, because the destination address was a valid address (by
> pure luck).
> 
> Make sure the PCI root is actually one of the expected PCIe layerscape
> controllers by matching its compatible string.
> 
> Signed-off-by: Michael Walle <michael at walle.cc>
> ---

This is equivalent to:
https://github.com/openil/u-boot/commit/6b5f833381a06503bb5fef3ef933cb62d3175e44

Sorry for not upstreaming it (and a bunch of other patches), I simply
gave up because the maintainer response time in U-Boot is so slow.

Reviewed-by: Vladimir Oltean <vladimir.oltean at nxp.com>

>  drivers/pci/pcie_layerscape_fixup.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/pci/pcie_layerscape_fixup.c b/drivers/pci/pcie_layerscape_fixup.c
> index 94de4edaf4..76706487e2 100644
> --- a/drivers/pci/pcie_layerscape_fixup.c
> +++ b/drivers/pci/pcie_layerscape_fixup.c
> @@ -187,6 +187,12 @@ static void fdt_fixup_pcie_ls(void *blob)
>  	     pci_find_next_device(&dev)) {
>  		for (bus = dev; device_is_on_pci_bus(bus);)
>  			bus = bus->parent;
> +
> +		/* Only do the fixups for layerscape PCIe controllers */
> +		if (!device_is_compatible(bus, "fsl,ls-pcie") &&
> +		    !device_is_compatible(bus, CONFIG_FSL_PCIE_COMPAT))
> +			continue;
> +
>  		pcie_rc = dev_get_priv(bus);
>  
>  		streamid = pcie_next_streamid(pcie_rc->stream_id_cur,
> -- 
> 2.20.1
> 

Thanks,
-Vladimir