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arch/rp23xx: add bounded timeout to SPI DMA completion wait - #20587
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xiaoxiang781216
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xiaoxiang781216
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The SPI DMA exchange path previously waited for completion with two untimed, uninterruptible semaphore waits (nxsem_wait_uninterruptible). If a DMA transfer never completes (e.g. stalled slave or bus glitch), the calling thread sleeps indefinitely. In network drivers like W5500 on SPI0 running from the LP work queue while holding net_lock, this causes the worker to hang permanently, wedging the whole network stack and blocking recovery handlers. This patch updates both ARM and RISC-V ports of rp23xx: - Switches to nxsem_tickwait_uninterruptible() with a transfer-size-derived timeout plus a safety margin. - On timeout, forcibly stops both DMA channels with rp23xx_dmastop(), disables SPI DMA in the control register, resets the semaphore count, drains leftover RX FIFO bytes, and logs an error to degrade gracefully instead of deadlocking. Fixes apache#19305 Signed-off-by: Sarthak Pandey <sarthak@email.com>
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Summary
Fixes #19305
The SPI DMA exchange path in
rp23xx_spi.cpreviously waited for DMA completion using two back-to-back untimed, uninterruptible semaphore waits (nxsem_wait_uninterruptible()). If a DMA transfer never completes (e.g. stalled slave device or bus glitch), the calling thread sleeps indefinitely without timeout.In network drivers such as W5500 Ethernet on SPI0 running from the LP work queue while holding
net_lock, this stalled wait causes the LP worker to sleep forever while holding the network lock, wedging the whole network stack (pinghangs, network shell commands block, and driver TX-timeout recovery cannot run).This patch addresses the issue for both ARM and RISC-V ports of rp23xx:
nxsem_tickwait_uninterruptible()and a dynamic timeout calculated from transfer size, SPI clock frequency, and a safety margin (100 ms).rp23xx_dmastop().SSPDMACR).nxsem_reset(&priv->dmasem, 0)) to avoid residual posts corrupting subsequent transfers.spierr()and returns instead of hanging forever.Impact
arch/arm/src/rp23xx/rp23xx_spi.c,arch/risc-v/src/rp23xx-rv/rp23xx_spi.c).net_lock, and run its TX timeout recovery handlers.Testing
nxstyle.