When serial_core pushes some new TX chars via a call to pl011_start_tx(), it can race with irqs triggered by ongoing transmission, overfilling the FIFO and causing characters to be silently dropped. This was originally reported by Phil Elwell [1], who proposed an initial fix. This series aims for a simpler and more robust solution to the problem. Any testing much appreciated! If all looks good, I can repost this on v5.3-rc1 when that arrives. As noted in the patches, I'm not sure that the second patch is necessary (or even desirable). Please test both with and without the second patch, and please comment if you have any thoughts on it :) [1] [PATCH] tty: amba-pl011: Make TX optimisation conditional http://lists.infradead.org/pipermail/linux-rpi-kernel/2019-July/008832.html Dave Martin (2): serial: pl011: Fix dropping of TX chars due to irq race serial: pl011: Don't bother pushing more TX data while TX irq is active drivers/tty/serial/amba-pl011.c | 11 +++++++++++ 1 file changed, 11 insertions(+) -- 2.1.4
