misc: rp1-pio: release DMA channel outside pio->lock#7519
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Fail transfers if they haven't first been configured. Signed-off-by: Phil Elwell <phil@raspberrypi.com>
rp1_pio_sm_dma_free() ends in dma_release_channel(), which sleeps while removing the sysfs links. Running it under pio->lock in SM_CONFIG_XFER triggers "BUG: scheduling while atomic" and hangs the machine when a client keeps reconfiguring a transfer. The claim bit stays set for this client across the unlock, so the channel remains reserved against other clients while it is released. Fixes: 0b7a604 ("misc: Add RP1 PIO driver") Link: raspberrypi#7512 Signed-off-by: Nicolai Buchwitz <nb@tipi-net.de>
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rp1_pio_sm_dma_free() ends in dma_release_channel(), which sleeps while
removing the sysfs links. Running it under pio->lock in SM_CONFIG_XFER
triggers "BUG: scheduling while atomic" and hangs the machine when a
client keeps reconfiguring a transfer.
The claim bit stays set for this client across the unlock, so the
channel remains reserved against other clients while it is released.