net: macb: manage BNA error and prevent RX lockup on GEM#7
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yseraf wants to merge 1 commit intolinux4microchip:linux-6.12-mchpfrom
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net: macb: manage BNA error and prevent RX lockup on GEM#7yseraf wants to merge 1 commit intolinux4microchip:linux-6.12-mchpfrom
yseraf wants to merge 1 commit intolinux4microchip:linux-6.12-mchpfrom
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This patch addresses a controller freeze occurring under high incoming traffic loads on GEM-based platforms like the ATSAMA5D41. When the DMA exhausted all available buffers, it triggered a Buffer Not Available (BNA) condition in the Receive Status Register (RSR). On this hardware, clearing the BNA flag without first resolving the underlying resource shortage caused the controller to enter a permanent blocked state. The recovery logic introduced here forces a slot release by incrementing the consumer index (rx_tail), acknowledges the error in RSR, and performs a descriptor refill before allowing NAPI to continue. To isolate this critical repair phase from asynchronous bus errors, the HRESP interrupt is transiently masked. This GEM-specific implementation is separated from the legacy MACB polling to avoid regressions on older architectures. Signed-off-by: Yannick Serafini <yannick.serafini@wifx.net>
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The bug and this patch can be easily tested using Packet Sender application with its UDP Traffic Generator utils : Without patch, the Ethernet controller gets stuck almost instantly (in few dozen of seconds). Note: the standard Ethernet controller behaviour and performance like bandwidth is not affected by the patch, it just makes the ATSAMA5Dxx a true network compatible CPU. |
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This patch addresses a controller freeze occurring under high incoming traffic loads on GEM-based platforms like the ATSAMA5D41. When the DMA exhausted all available buffers, it triggered a Buffer Not Available (BNA) condition in the Receive Status Register (RSR).
On this hardware, clearing the BNA flag without first resolving the underlying resource shortage caused the controller to enter a permanent blocked state. The recovery logic introduced here forces a slot release by incrementing the consumer index (rx_tail), acknowledges the error in RSR, and performs a descriptor refill before allowing NAPI to continue. To isolate this critical repair phase from asynchronous bus errors, the HRESP interrupt is transiently masked. This GEM-specific implementation is separated from the legacy MACB polling to avoid regressions on older architectures.