[PATCH net v3] net: ti: icssg-prueth: Fix buffer allocation for ICSSG
Simon Horman
horms at kernel.org
Fri Jul 18 07:27:39 PDT 2025
On Thu, Jul 17, 2025 at 03:12:20PM +0530, Himanshu Mittal wrote:
> Fixes overlapping buffer allocation for ICSSG peripheral
> used for storing packets to be received/transmitted.
> There are 3 buffers:
> 1. Buffer for Locally Injected Packets
> 2. Buffer for Forwarding Packets
> 3. Buffer for Host Egress Packets
>
> In existing allocation buffers for 2. and 3. are overlapping causing
> packet corruption.
>
> Packet corruption observations:
> During tcp iperf testing, due to overlapping buffers the received ack
> packet overwrites the packet to be transmitted. So, we see packets on
> wire with the ack packet content inside the content of next TCP packet
> from sender device.
>
> Details for AM64x switch mode:
> -> Allocation by existing driver:
> +---------+-------------------------------------------------------------+
> | | SLICE 0 | SLICE 1 |
> | +------+--------------+--------+------+--------------+--------+
> | | Slot | Base Address | Size | Slot | Base Address | Size |
> |---------+------+--------------+--------+------+--------------+--------+
> | | 0 | 70000000 | 0x2000 | 0 | 70010000 | 0x2000 |
> | | 1 | 70002000 | 0x2000 | 1 | 70012000 | 0x2000 |
> | | 2 | 70004000 | 0x2000 | 2 | 70014000 | 0x2000 |
> | FWD | 3 | 70006000 | 0x2000 | 3 | 70016000 | 0x2000 |
> | Buffers | 4 | 70008000 | 0x2000 | 4 | 70018000 | 0x2000 |
> | | 5 | 7000A000 | 0x2000 | 5 | 7001A000 | 0x2000 |
> | | 6 | 7000C000 | 0x2000 | 6 | 7001C000 | 0x2000 |
> | | 7 | 7000E000 | 0x2000 | 7 | 7001E000 | 0x2000 |
> +---------+------+--------------+--------+------+--------------+--------+
> | | 8 | 70020000 | 0x1000 | 8 | 70028000 | 0x1000 |
> | | 9 | 70021000 | 0x1000 | 9 | 70029000 | 0x1000 |
> | | 10 | 70022000 | 0x1000 | 10 | 7002A000 | 0x1000 |
> | Our | 11 | 70023000 | 0x1000 | 11 | 7002B000 | 0x1000 |
> | LI | 12 | 00000000 | 0x0 | 12 | 00000000 | 0x0 |
> | Buffers | 13 | 00000000 | 0x0 | 13 | 00000000 | 0x0 |
> | | 14 | 00000000 | 0x0 | 14 | 00000000 | 0x0 |
> | | 15 | 00000000 | 0x0 | 15 | 00000000 | 0x0 |
> +---------+------+--------------+--------+------+--------------+--------+
> | | 16 | 70024000 | 0x1000 | 16 | 7002C000 | 0x1000 |
> | | 17 | 70025000 | 0x1000 | 17 | 7002D000 | 0x1000 |
> | | 18 | 70026000 | 0x1000 | 18 | 7002E000 | 0x1000 |
> | Their | 19 | 70027000 | 0x1000 | 19 | 7002F000 | 0x1000 |
> | LI | 20 | 00000000 | 0x0 | 20 | 00000000 | 0x0 |
> | Buffers | 21 | 00000000 | 0x0 | 21 | 00000000 | 0x0 |
> | | 22 | 00000000 | 0x0 | 22 | 00000000 | 0x0 |
> | | 23 | 00000000 | 0x0 | 23 | 00000000 | 0x0 |
> +---------+------+--------------+--------+------+--------------+--------+
> --> here 16, 17, 18, 19 overlapping with below express buffer
>
> +-----+-----------------------------------------------+
> | | SLICE 0 | SLICE 1 |
> | +------------+----------+------------+----------+
> | | Start addr | End addr | Start addr | End addr |
> +-----+------------+----------+------------+----------+
> | EXP | 70024000 | 70028000 | 7002C000 | 70030000 | <-- Overlapping
> | PRE | 70030000 | 70033800 | 70034000 | 70037800 |
> +-----+------------+----------+------------+----------+
>
> +---------------------+----------+----------+
> | | SLICE 0 | SLICE 1 |
> +---------------------+----------+----------+
> | Default Drop Offset | 00000000 | 00000000 | <-- Field not configured
> +---------------------+----------+----------+
>
> -> Allocation this patch brings:
> +---------+-------------------------------------------------------------+
> | | SLICE 0 | SLICE 1 |
> | +------+--------------+--------+------+--------------+--------+
> | | Slot | Base Address | Size | Slot | Base Address | Size |
> |---------+------+--------------+--------+------+--------------+--------+
> | | 0 | 70000000 | 0x2000 | 0 | 70040000 | 0x2000 |
> | | 1 | 70002000 | 0x2000 | 1 | 70042000 | 0x2000 |
> | | 2 | 70004000 | 0x2000 | 2 | 70044000 | 0x2000 |
> | FWD | 3 | 70006000 | 0x2000 | 3 | 70046000 | 0x2000 |
> | Buffers | 4 | 70008000 | 0x2000 | 4 | 70048000 | 0x2000 |
> | | 5 | 7000A000 | 0x2000 | 5 | 7004A000 | 0x2000 |
> | | 6 | 7000C000 | 0x2000 | 6 | 7004C000 | 0x2000 |
> | | 7 | 7000E000 | 0x2000 | 7 | 7004E000 | 0x2000 |
> +---------+------+--------------+--------+------+--------------+--------+
> | | 8 | 70010000 | 0x1000 | 8 | 70050000 | 0x1000 |
> | | 9 | 70011000 | 0x1000 | 9 | 70051000 | 0x1000 |
> | | 10 | 70012000 | 0x1000 | 10 | 70052000 | 0x1000 |
> | Our | 11 | 70013000 | 0x1000 | 11 | 70053000 | 0x1000 |
> | LI | 12 | 00000000 | 0x0 | 12 | 00000000 | 0x0 |
> | Buffers | 13 | 00000000 | 0x0 | 13 | 00000000 | 0x0 |
> | | 14 | 00000000 | 0x0 | 14 | 00000000 | 0x0 |
> | | 15 | 00000000 | 0x0 | 15 | 00000000 | 0x0 |
> +---------+------+--------------+--------+------+--------------+--------+
> | | 16 | 70014000 | 0x1000 | 16 | 70054000 | 0x1000 |
> | | 17 | 70015000 | 0x1000 | 17 | 70055000 | 0x1000 |
> | | 18 | 70016000 | 0x1000 | 18 | 70056000 | 0x1000 |
> | Their | 19 | 70017000 | 0x1000 | 19 | 70057000 | 0x1000 |
> | LI | 20 | 00000000 | 0x0 | 20 | 00000000 | 0x0 |
> | Buffers | 21 | 00000000 | 0x0 | 21 | 00000000 | 0x0 |
> | | 22 | 00000000 | 0x0 | 22 | 00000000 | 0x0 |
> | | 23 | 00000000 | 0x0 | 23 | 00000000 | 0x0 |
> +---------+------+--------------+--------+------+--------------+--------+
>
> +-----+-----------------------------------------------+
> | | SLICE 0 | SLICE 1 |
> | +------------+----------+------------+----------+
> | | Start addr | End addr | Start addr | End addr |
> +-----+------------+----------+------------+----------+
> | EXP | 70018000 | 7001C000 | 70058000 | 7005C000 |
> | PRE | 7001C000 | 7001F800 | 7005C000 | 7005F800 |
> +-----+------------+----------+------------+----------+
>
> +---------------------+----------+----------+
> | | SLICE 0 | SLICE 1 |
> +---------------------+----------+----------+
> | Default Drop Offset | 7001F800 | 7005F800 |
> +---------------------+----------+----------+
>
> Rootcause: missing buffer configuration for Express frames in
> function: prueth_fw_offload_buffer_setup()
>
> Details:
> Driver implements two distinct buffer configuration functions that are
> invoked based on the driver state and ICSSG firmware:-
> - prueth_fw_offload_buffer_setup()
> - prueth_emac_buffer_setup()
>
> During initialization, driver creates standard network interfaces
> (netdevs) and configures buffers via prueth_emac_buffer_setup().
> This function properly allocates and configures all required memory
> regions including:
> - LI buffers
> - Express packet buffers
> - Preemptible packet buffers
>
> However, when the driver transitions to an offload mode (switch/HSR/PRP),
> buffer reconfiguration is handled by prueth_fw_offload_buffer_setup().
> This function does not reconfigure the buffer regions required for
> Express packets, leading to incorrect buffer allocation.
>
> Fixes: abd5576b9c57 ("net: ti: icssg-prueth: Add support for ICSSG switch firmware")
> Signed-off-by: Himanshu Mittal <h-mittal1 at ti.com>
Thanks for the updated patch description.
Reviewed-by: Simon Horman <horms at kernel.org>
FTR, I did spend some time looking over the mappings described
above and correlating them with both the code and the "Details" above.
I agree with the analysis above and that the patchset addresses
the problem as described.
...
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