Commit e8ffbb71 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by Greg Kroah-Hartman

serial: 8250: use THRE & __stop_tx also with DMA

8250 DMA tx complete path lacks calls to normal 8250 stop handling. It
does not use THRE to detect true completion of the tx and also doesn't
call __stop_tx. This leads to problems with em485 that needs to handle
RTS timing.

Instead of handling tx stop internally within 8250 dma code, enable
THRE when tx'able data runs out and tweak serial8250_handle_irq to call
only __stop_tx when uart is using DMA.

It also seems bit early to call serial8250_rpm_put_tx from there while
tx is still underway(?).
Tested-by: default avatarVicente Bergas <vicencb@gmail.com>
Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220425143410.12703-3-ilpo.jarvinen@linux.intel.comSigned-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 31f6bd7f
......@@ -34,7 +34,7 @@ static void __dma_tx_complete(void *param)
uart_write_wakeup(&p->port);
ret = serial8250_tx_dma(p);
if (ret)
if (ret || !dma->tx_running)
serial8250_set_THRI(p);
spin_unlock_irqrestore(&p->port.lock, flags);
......@@ -80,7 +80,6 @@ int serial8250_tx_dma(struct uart_8250_port *p)
if (uart_tx_stopped(&p->port) || uart_circ_empty(xmit)) {
/* We have been called from __dma_tx_complete() */
serial8250_rpm_put_tx(p);
return 0;
}
......
......@@ -1948,9 +1948,12 @@ int serial8250_handle_irq(struct uart_port *port, unsigned int iir)
status = serial8250_rx_chars(up, status);
}
serial8250_modem_status(up);
if ((!up->dma || up->dma->tx_err) && (status & UART_LSR_THRE) &&
(up->ier & UART_IER_THRI))
if ((status & UART_LSR_THRE) && (up->ier & UART_IER_THRI)) {
if (!up->dma || up->dma->tx_err)
serial8250_tx_chars(up);
else
__stop_tx(up);
}
uart_unlock_and_check_sysrq_irqrestore(port, flags);
......
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