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Diffstat (limited to 'target/linux/brcm2708/patches-4.19/950-0796-tty-amba-pl011-Add-un-throttle-support.patch')
-rw-r--r--target/linux/brcm2708/patches-4.19/950-0796-tty-amba-pl011-Add-un-throttle-support.patch61
1 files changed, 61 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.19/950-0796-tty-amba-pl011-Add-un-throttle-support.patch b/target/linux/brcm2708/patches-4.19/950-0796-tty-amba-pl011-Add-un-throttle-support.patch
new file mode 100644
index 0000000000..0ab6cf2fe9
--- /dev/null
+++ b/target/linux/brcm2708/patches-4.19/950-0796-tty-amba-pl011-Add-un-throttle-support.patch
@@ -0,0 +1,61 @@
+From d4f4b57c667141ca98711cfcb30ae2b8deb1a034 Mon Sep 17 00:00:00 2001
+From: Phil Elwell <phil@raspberrypi.org>
+Date: Fri, 24 Jan 2020 11:38:28 +0000
+Subject: [PATCH] tty: amba-pl011: Add un/throttle support
+
+The PL011 driver lacks throttle and unthrottle methods. As a result,
+sending more data to the Pi than it can immediately sink while CRTSCTS
+is enabled causes a NULL pointer to be followed.
+
+Add a throttle handler that disables the RX interrupts, and an
+unthrottle handler that reenables them.
+
+Signed-off-by: Phil Elwell <phil@raspberrypi.org>
+---
+ drivers/tty/serial/amba-pl011.c | 28 ++++++++++++++++++++++++++++
+ 1 file changed, 28 insertions(+)
+
+--- a/drivers/tty/serial/amba-pl011.c
++++ b/drivers/tty/serial/amba-pl011.c
+@@ -1323,6 +1323,32 @@ static void pl011_start_tx(struct uart_p
+ pl011_start_tx_pio(uap);
+ }
+
++static void pl011_throttle(struct uart_port *port)
++{
++ struct uart_amba_port *uap =
++ container_of(port, struct uart_amba_port, port);
++ unsigned long flags;
++
++ spin_lock_irqsave(&uap->port.lock, flags);
++ uap->im &= ~(UART011_RTIM | UART011_RXIM);
++ pl011_write(uap->im, uap, REG_IMSC);
++ spin_unlock_irqrestore(&uap->port.lock, flags);
++}
++
++static void pl011_unthrottle(struct uart_port *port)
++{
++ struct uart_amba_port *uap =
++ container_of(port, struct uart_amba_port, port);
++ unsigned long flags;
++
++ spin_lock_irqsave(&uap->port.lock, flags);
++ uap->im |= UART011_RTIM;
++ if (!pl011_dma_rx_running(uap))
++ uap->im |= UART011_RXIM;
++ pl011_write(uap->im, uap, REG_IMSC);
++ spin_unlock_irqrestore(&uap->port.lock, flags);
++}
++
+ static void pl011_stop_rx(struct uart_port *port)
+ {
+ struct uart_amba_port *uap =
+@@ -2165,6 +2191,8 @@ static const struct uart_ops amba_pl011_
+ .stop_tx = pl011_stop_tx,
+ .start_tx = pl011_start_tx,
+ .stop_rx = pl011_stop_rx,
++ .throttle = pl011_throttle,
++ .unthrottle = pl011_unthrottle,
+ .enable_ms = pl011_enable_ms,
+ .break_ctl = pl011_break_ctl,
+ .startup = pl011_startup,