openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

serial: 8250: 8250_omap: Account for data in flight during DMA teardown 

Take into account data stuck in DMA internal buffers before pushing data
to higher layer. dma_tx_state has "in_flight_bytes" member that provides
this information.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20200319110344.21348-3-vigneshr@ti.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Vignesh Raghavendra 2020-03-19 16:33:40 +05:30 committed by Greg Kroah-Hartman
parent 7cf4df30a9
commit 4bcf59a5de
1 changed files with 23 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
drivers/tty/serial/8250/8250_omap.c
View File

@ -741,6 +741,8 @@ static void __dma_rx_do_complete(struct uart_8250_port *p)
struct omap8250_priv *priv = p->port.private_data;
struct uart_8250_dma *dma = p->dma;
struct tty_port *tty_port = &p->port.state->port;
struct dma_chan *rxchan = dma->rxchan;
dma_cookie_t cookie;
struct dma_tx_state state;
int count;
unsigned long flags;
@ -751,12 +753,29 @@ static void __dma_rx_do_complete(struct uart_8250_port *p)
if (!dma->rx_running)
goto unlock;
cookie = dma->rx_cookie;
dma->rx_running = 0;
dmaengine_tx_status(dma->rxchan, dma->rx_cookie, &state);
dmaengine_tx_status(rxchan, cookie, &state);
count = dma->rx_size - state.residue;
if (count < dma->rx_size)
dmaengine_terminate_async(dma->rxchan);
count = dma->rx_size - state.residue + state.in_flight_bytes;
if (count < dma->rx_size) {
dmaengine_terminate_async(rxchan);
/*
* Poll for teardown to complete which guarantees in
* flight data is drained.
*/
if (state.in_flight_bytes) {
int poll_count = 25;
while (dmaengine_tx_status(rxchan, cookie, NULL) &&
poll_count--)
cpu_relax();
if (!poll_count)
dev_err(p->port.dev, "teardown incomplete\n");
}
}
if (!count)
goto unlock;
ret = tty_insert_flip_string(tty_port, dma->rx_buf, count);