ath79: ar933x_uart: set UART_CS_{RX,TX}_READY_ORIDE

On AR934x this UART is usually not initialized by the bootloader
as it is only used as a secondary serial port while the primary
UART is a newly introduced NS16550-compatible.
In order to make use of the ar933x-uart on AR934x without RTS/CTS
hardware flow control, one needs to set the
UART_CS_{RX,TX}_READY_ORIDE bits as other than on AR933x where this
UART is used as primary/console, the bootloader on AR934x typically
doesn't set those bits.
Setting them explicitely on AR933x does not do any harm, so just set
them unconditionally.

Tested-by: Chuanhong Guo <gch981213@gmail.com
Signed-off-by: Daniel Golle <daniel@makrotopia.org>

1 files changed, 64 insertions, 0 deletions

diff --git a/target/linux/ath79/patches-4.19/0060-serial-ar933x_uart-set-UART_CS_-RX-TX-_READY_ORIDE.patch b/target/linux/ath79/patches-4.19/0060-serial-ar933x_uart-set-UART_CS_-RX-TX-_READY_ORIDE.patch
new file mode 100644
index 0000000000..2ed520683e
--- /dev/null
+++ b/target/linux/ath79/patches-4.19/0060-serial-ar933x_uart-set-UART_CS_-RX-TX-_READY_ORIDE.patch
@@ -0,0 +1,64 @@
+From patchwork Fri Feb  7 09:53:35 2020
+Content-Type: text/plain; charset="utf-8"
+MIME-Version: 1.0
+Content-Transfer-Encoding: 7bit
+X-Patchwork-Submitter: Daniel Golle <daniel@makrotopia.org>
+X-Patchwork-Id: 1190470
+Date: Fri, 7 Feb 2020 11:53:35 +0200
+From: Daniel Golle <daniel@makrotopia.org>
+To: linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
+Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
+        Jiri Slaby <jslaby@suse.com>,
+        Chuanhong Guo <gch981213@gmail.com>,
+        Eitan Cohen <eitan@neot-semadar.com>,
+        Ori Gofen <origofen@gmail.com>
+Subject: [PATCH] serial: ar933x_uart: set UART_CS_{RX,TX}_READY_ORIDE
+Message-ID: <20200207095335.GA179836@makrotopia.org>
+MIME-Version: 1.0
+Content-Disposition: inline
+Sender: linux-kernel-owner@vger.kernel.org
+Precedence: bulk
+List-ID: <linux-kernel.vger.kernel.org>
+X-Mailing-List: linux-kernel@vger.kernel.org
+
+On AR934x this UART is usually not initialized by the bootloader
+as it is only used as a secondary serial port while the primary
+UART is a newly introduced NS16550-compatible.
+In order to make use of the ar933x-uart on AR934x without RTS/CTS
+hardware flow control, one needs to set the
+UART_CS_{RX,TX}_READY_ORIDE bits as other than on AR933x where this
+UART is used as primary/console, the bootloader on AR934x typically
+doesn't set those bits.
+Setting them explicitely on AR933x should not do any harm, so just
+set them unconditionally.
+
+Tested-by: Chuanhong Guo <gch981213@gmail.com>
+Signed-off-by: Daniel Golle <daniel@makrotopia.org>
+---
+ drivers/tty/serial/ar933x_uart.c | 8 ++++++++
+ 1 file changed, 8 insertions(+)
+
+--- a/drivers/tty/serial/ar933x_uart.c
++++ b/drivers/tty/serial/ar933x_uart.c
+@@ -328,6 +328,10 @@ static void ar933x_uart_set_termios(stru
+ 	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
+ 			    AR933X_UART_CS_HOST_INT_EN);
+ 
++	/* enable RX and TX ready overide */
++	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
++		AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE);
++
+ 	/* reenable the UART */
+ 	ar933x_uart_rmw(up, AR933X_UART_CS_REG,
+ 			AR933X_UART_CS_IF_MODE_M << AR933X_UART_CS_IF_MODE_S,
+@@ -460,6 +464,10 @@ static int ar933x_uart_startup(struct ua
+ 	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
+ 			    AR933X_UART_CS_HOST_INT_EN);
+ 
++	/* enable RX and TX ready overide */
++	ar933x_uart_rmw_set(up, AR933X_UART_CS_REG,
++		AR933X_UART_CS_TX_READY_ORIDE | AR933X_UART_CS_RX_READY_ORIDE);
++
+ 	/* Enable RX interrupts */
+ 	up->ier = AR933X_UART_INT_RX_VALID;
+ 	ar933x_uart_write(up, AR933X_UART_INT_EN_REG, up->ier);