On 20.05.2025 16:57, Andriy Gapon wrote:
The branch main has been updated by avg:
URL:
https://cgit.FreeBSD.org/src/commit/?id=0d2fd5b99c95329085d0700a4dd38507a054a50d
commit 0d2fd5b99c95329085d0700a4dd38507a054a50d
Author: Andriy Gapon <a...@freebsd.org>
AuthorDate: 2024-11-10 11:15:30 +0000
Commit: Andriy Gapon <a...@freebsd.org>
CommitDate: 2025-05-20 14:55:18 +0000
ns8250: use LSR_THRE instead of LSR_TEMT for checking tx flush
LSR_TEMT bit is set if both transmit hold and shift registers are
empty, but the flush command flushes only the hold register.
I don't think that's true. Imho, ns8250_flush() is used also before
changing baud rate, so we need to ensure that all bits are flushed,
including the transmit register.
Michal
While here, update the diagnostic message to report which registers
could not be flushed.
MFC after: 2 weeks
---
sys/dev/uart/uart_dev_ns8250.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/sys/dev/uart/uart_dev_ns8250.c b/sys/dev/uart/uart_dev_ns8250.c
index 1df39b499539..0f19ede6d9df 100644
--- a/sys/dev/uart/uart_dev_ns8250.c
+++ b/sys/dev/uart/uart_dev_ns8250.c
@@ -265,12 +265,12 @@ ns8250_flush(struct uart_bas *bas, int what)
* https://github.com/rust-vmm/vm-superio/issues/83
*/
lsr = uart_getreg(bas, REG_LSR);
- if (((lsr & LSR_TEMT) == 0) && (what & UART_FLUSH_TRANSMITTER))
+ if (((lsr & LSR_THRE) == 0) && (what & UART_FLUSH_TRANSMITTER))
drain |= UART_DRAIN_TRANSMITTER;
if ((lsr & LSR_RXRDY) && (what & UART_FLUSH_RECEIVER))
drain |= UART_DRAIN_RECEIVER;
if (drain != 0) {
- printf("uart: ns8250: UART FCR is broken\n");
+ printf("uart: ns8250: UART FCR is broken (%#x)\n", drain);
ns8250_drain(bas, drain);
}
}
