Noralf Trønnes <noralf@xxxxxxxxxxx> writes: > Writing messages larger than the FIFO size results in a hang, rendering > the machine unusable. This is because the RXD status flag is set on the > first interrupt which results in bcm2835_drain_rxfifo() stealing bytes > from the buffer. The controller continues to trigger interrupts waiting > for the missing bytes, but bcm2835_fill_txfifo() has none to give. > In this situation wait_for_completion_timeout() apparently is unable to > stop the madness. > > The BCM2835 ARM Peripherals datasheet has this to say about the flags: > TXD: is set when the FIFO has space for at least one byte of data. > RXD: is set when the FIFO contains at least one byte of data. > TXW: is set during a write transfer and the FIFO is less than full. > RXR: is set during a read transfer and the FIFO is or more full. > > Implementing the logic from the downstream i2c-bcm2708 driver solved > the hang problem. > > Signed-off-by: Noralf Trønnes <noralf@xxxxxxxxxxx> Patches 1, 3 are: Reviewed-by: Eric Anholt <eric@xxxxxxxxxx> For patch 2 I followed some of it, but couldn't quite say it's a review. I trust your testing, and that the path has had a lot more testing in the downstream tree, so it's: Acked-by: Eric Anholt <eric@xxxxxxxxxx> Thanks!
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