net: macb: manage BNA error and prevent RX lockup on GEM #7
+72
−1
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
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 <[email protected]>
Author
|
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. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
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.