From 5fe86674840c6773d09943a78a5f7f3bf2420ffd Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Mon, 14 Nov 2016 12:26:52 +0200 Subject: [PATCH] serial: 8250_dma: power off device after TX is done When any 8250 based driver sets up DMA and has UART_CAP_RPM capability enabled the device is left powered on after transfer is done. We need to schedule a device suspend operation when DMA completes the transfer. The patch is based on the work done by the reporter. Reported-by: Huiquan Zhong Signed-off-by: Andy Shevchenko Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/8250/8250_dma.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_dma.c b/drivers/tty/serial/8250/8250_dma.c index fdbddbc6375d..26f17456b0d7 100644 --- a/drivers/tty/serial/8250/8250_dma.c +++ b/drivers/tty/serial/8250/8250_dma.c @@ -72,10 +72,15 @@ int serial8250_tx_dma(struct uart_8250_port *p) struct dma_async_tx_descriptor *desc; int ret; - if (uart_tx_stopped(&p->port) || dma->tx_running || - uart_circ_empty(xmit)) + if (dma->tx_running) return 0; + 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; + } + dma->tx_size = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE); desc = dmaengine_prep_slave_single(dma->txchan, -- 2.20.1