4.9-stable patches

added patches:
	tty-serial-atmel-rs485-hd-w-dma-enable-rx-after-tx-is-stopped.patch

diff --git a/queue-4.9/series b/queue-4.9/series
index c16607f74dfdae8b59b741333a0dae08641f43b8..c07d3025d7865486b0526c21e5ee488b3be1ce0e 100644 (file)
--- a/queue-4.9/series
+++ b/queue-4.9/series
@@ -3,5 +3,6 @@ arm64-debug-ensure-debug-handlers-check-triggering-exception-level.patch
 ext4-cleanup-bh-release-code-in-ext4_ind_remove_space.patch
 lib-int_sqrt-optimize-initial-value-compute.patch
 tty-serial-atmel-add-is_half_duplex-helper.patch
+tty-serial-atmel-rs485-hd-w-dma-enable-rx-after-tx-is-stopped.patch
 mm-mempolicy-make-mbind-return-eio-when-mpol_mf_strict-is-specified.patch
 i2c-core-smbus-prevent-stack-corruption-on-read-i2c_block_data.patch

diff --git a/queue-4.9/tty-serial-atmel-rs485-hd-w-dma-enable-rx-after-tx-is-stopped.patch b/queue-4.9/tty-serial-atmel-rs485-hd-w-dma-enable-rx-after-tx-is-stopped.patch
new file mode 100644 (file)
index 0000000..483e3d8
--- /dev/null
+++ b/queue-4.9/tty-serial-atmel-rs485-hd-w-dma-enable-rx-after-tx-is-stopped.patch
@@ -0,0 +1,79 @@
+From 69646d7a3689fbe1a65ae90397d22ac3f1b8d40f Mon Sep 17 00:00:00 2001
+From: Razvan Stefanescu <razvan.stefanescu@microchip.com>
+Date: Tue, 19 Mar 2019 15:20:35 +0200
+Subject: tty/serial: atmel: RS485 HD w/DMA: enable RX after TX is stopped
+
+From: Razvan Stefanescu <razvan.stefanescu@microchip.com>
+
+commit 69646d7a3689fbe1a65ae90397d22ac3f1b8d40f upstream.
+
+In half-duplex operation, RX should be started after TX completes.
+
+If DMA is used, there is a case when the DMA transfer completes but the
+TX FIFO is not emptied, so the RX cannot be restarted just yet.
+
+Use a boolean variable to store this state and rearm TX interrupt mask
+to be signaled again that the transfer finished. In interrupt transmit
+handler this variable is used to start RX. A warning message is generated
+if RX is activated before TX fifo is cleared.
+
+Fixes: b389f173aaa1 ("tty/serial: atmel: RS485 half duplex w/DMA: enable
+RX after TX is done")
+Signed-off-by: Razvan Stefanescu <razvan.stefanescu@microchip.com>
+Acked-by: Richard Genoud <richard.genoud@gmail.com>
+Cc: stable <stable@vger.kernel.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ drivers/tty/serial/atmel_serial.c |   24 +++++++++++++++++++++---
+ 1 file changed, 21 insertions(+), 3 deletions(-)
+
+--- a/drivers/tty/serial/atmel_serial.c
++++ b/drivers/tty/serial/atmel_serial.c
+@@ -175,6 +175,8 @@ struct atmel_uart_port {
+       unsigned int            pending_status;
+       spinlock_t              lock_suspended;
+ 
++      bool                    hd_start_rx;    /* can start RX during half-duplex operation */
++
+       int (*prepare_rx)(struct uart_port *port);
+       int (*prepare_tx)(struct uart_port *port);
+       void (*schedule_rx)(struct uart_port *port);
+@@ -815,8 +817,13 @@ static void atmel_complete_tx_dma(void *
+       if (!uart_circ_empty(xmit))
+               atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
+       else if (atmel_uart_is_half_duplex(port)) {
+-              /* DMA done, stop TX, start RX for RS485 */
+-              atmel_start_rx(port);
++              /*
++               * DMA done, re-enable TXEMPTY and signal that we can stop
++               * TX and start RX for RS485
++               */
++              atmel_port->hd_start_rx = true;
++              atmel_uart_writel(port, ATMEL_US_IER,
++                                atmel_port->tx_done_mask);
+       }
+ 
+       spin_unlock_irqrestore(&port->lock, flags);
+@@ -1261,9 +1268,20 @@ atmel_handle_transmit(struct uart_port *
+       struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+ 
+       if (pending & atmel_port->tx_done_mask) {
+-              /* Either PDC or interrupt transmission */
+               atmel_uart_writel(port, ATMEL_US_IDR,
+                                 atmel_port->tx_done_mask);
++
++              /* Start RX if flag was set and FIFO is empty */
++              if (atmel_port->hd_start_rx) {
++                      if (!(atmel_uart_readl(port, ATMEL_US_CSR)
++                                      & ATMEL_US_TXEMPTY))
++                              dev_warn(port->dev, "Should start RX, but TX fifo is not empty\n");
++
++                      atmel_port->hd_start_rx = false;
++                      atmel_start_rx(port);
++                      return;
++              }
++
+               atmel_tasklet_schedule(atmel_port, &atmel_port->tasklet_tx);
+       }
+ }