[SLOF] [PATCH] pci: Fix secondary and subordinate PCI bus enumeration with board-qemu

[Alexey Kardashevskiy]

On 27/09/16 21:52, Thomas Huth wrote:
> SLOF currently fails to correctly initialize the secondary and
> subordinate bus number registers in the config space of PCI
> bridges, so that for example with the following command line,
> none of the PCI devices is usable:
> 
>  qemu-system-ppc64 -nodefaults -nographic -serial mon:stdio \
>     -device pci-bridge,chassis_nr=1,id=bridge0,addr=0x3 \
>     -device pci-bridge,chassis_nr=2,id=bridge1,addr=0x4 \
>     -device virtio-balloon,bus=bridge1,addr=0x1 \
>     -device virtio-net,bus=bridge0,addr=0x2 \
>     -device virtio-rng,bus=bridge0,addr=0x5 \
>     -device pci-bridge,chassis_nr=3,id=br2,addr=0x6,bus=bridge1 \
>     -device e1000,bus=br2,addr=0x1
> 
> This is because SLOF tries to enumerate the PCI bus numbers
> that are reachable via a bridge. In the function pci-bridge-probe,
> it increases the pci-bus-number counter and writes that value into
> the secondary bus number register of the PCI config space, and
> after probing all attached bridges, it fills the number of the
> last enumerated bus number into the subordinate bus number register.
> This works fine if the whole bus enumeration is done by SLOF,
> however on board-qemu, we nowadays rely on the pre-initialized PCI
> device tree from QEMU - and the numbers that SLOF is trying to use
> here do not match with the bus numbers that QEMU already assigned
> to the bus segments (QEMU provides the device tree nodes in
> descending order, but SLOF tries to enumerate the bus numbers in
> ascending order here instead).
> 
> To fix this issue, we should simply stop setting up the secondary
> and subordinate config space registers of the bridge in SLOF - since
> this is done by QEMU already! Thus we replace the "pci-bridge-probe"
> function with a board-qemu-specific function "phb-pci-bridge-probe",
> that does not call "pci-bus!" and "pci-bus-subo!" anymore. (And since
> pci-bridge-probe was the only spot that called phb-pci-probe-bus, we
> can get rid of that wrapper now, too, and call phb-pci-walk-bridge
> from phb-pci-bridge-probe directly instead).
> 
> Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1377083
> Signed-off-by: Thomas Huth <thuth at redhat.com>

Thanks, applied.

> ---
>  board-qemu/slof/pci-phb.fs | 15 +++++++++++----
>  slof/fs/pci-properties.fs  |  2 +-
>  slof/fs/pci-scan.fs        |  2 ++
>  3 files changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/board-qemu/slof/pci-phb.fs b/board-qemu/slof/pci-phb.fs
> index f79c5b4..667514e 100644
> --- a/board-qemu/slof/pci-phb.fs
> +++ b/board-qemu/slof/pci-phb.fs
> @@ -304,9 +304,16 @@ setup-puid
>      get-parent set-node
>  ;
>  
> -\ Landing routing to probe the popuated device tree
> -: phb-pci-probe-bus ( busnr -- )
> -    drop phb-pci-walk-bridge
> +\ Similar to pci-bridge-probe, but without setting the secondary and
> +\ subordinate bus numbers (since this has been done by QEMU already)
> +: phb-pci-bridge-probe ( addr -- )
> +    dup pci-bridge-set-bases                      \ Set up all Base Registers
> +    dup func-pci-bridge-range-props               \ Set up temporary "range"
> +    pci-device-vec-len 1+ TO pci-device-vec-len   \ increase the device-slot vector depth
> +    pci-enable                                    \ enable mem/IO transactions
> +    phb-pci-walk-bridge                           \ and walk the secondary bus
> +    pci-device-vec-len 1- TO pci-device-vec-len   \ decrease the device-slot vector depth
> +    pci-bridge-set-limits                         \ Set up all Limit Registers
>  ;
>  
>  \ Stub routine, as qemu has enumerated, we already have the device
> @@ -328,7 +335,7 @@ setup-puid
>         1 0 (probe-pci-host-bridge)
>     ELSE
>         2drop
> -       ['] phb-pci-probe-bus TO func-pci-probe-bus
> +       ['] phb-pci-bridge-probe TO func-pci-bridge-probe
>         ['] phb-pci-device-props TO func-pci-device-props
>         phb-pci-walk-bridge          \ PHB device tree is already populated.
>     THEN
> diff --git a/slof/fs/pci-properties.fs b/slof/fs/pci-properties.fs
> index 4f13402..7faa714 100644
> --- a/slof/fs/pci-properties.fs
> +++ b/slof/fs/pci-properties.fs
> @@ -643,7 +643,7 @@
>          pci-device-slots >r             \ save the slot array on return stack
>          dup pci-common-props            \ set the common properties before scanning the bus
>          s" pci" device-type             \ the type is allways "pci"
> -        dup pci-bridge-probe            \ find all device connected to it
> +        dup func-pci-bridge-probe       \ find all device connected to it
>          dup assign-all-bridge-bars      \ set up all memory access BARs
>          dup pci-set-irq-line            \ set the interrupt pin
>          dup pci-set-capabilities        \ set up the capabilities
> diff --git a/slof/fs/pci-scan.fs b/slof/fs/pci-scan.fs
> index 2fdf0e8..a528c8e 100644
> --- a/slof/fs/pci-scan.fs
> +++ b/slof/fs/pci-scan.fs
> @@ -221,6 +221,8 @@ DEFER func-pci-bridge-range-props
>          dup pci-bridge-set-limits                       \ SetUp all Limit Registers
>          drop                                            \ forget the config-addr
>  ;
> +DEFER func-pci-bridge-probe
> +' pci-bridge-probe TO func-pci-bridge-probe
>  
>  \ set up the pci-device
>  : pci-device-setup ( addr -- )
> 


-- 
Alexey