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Diffstat (limited to 'target/linux/brcm2708/patches-4.14/950-0122-amba_pl011-Add-cts-event-workaround-DT-property.patch')
-rw-r--r--target/linux/brcm2708/patches-4.14/950-0122-amba_pl011-Add-cts-event-workaround-DT-property.patch47
1 files changed, 47 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.14/950-0122-amba_pl011-Add-cts-event-workaround-DT-property.patch b/target/linux/brcm2708/patches-4.14/950-0122-amba_pl011-Add-cts-event-workaround-DT-property.patch
new file mode 100644
index 0000000000..2e994e3743
--- /dev/null
+++ b/target/linux/brcm2708/patches-4.14/950-0122-amba_pl011-Add-cts-event-workaround-DT-property.patch
@@ -0,0 +1,47 @@
+From ca1ca821f735ad6284fa0c6228f27415e90f7a8f Mon Sep 17 00:00:00 2001
+From: Phil Elwell <phil@raspberrypi.org>
+Date: Fri, 29 Sep 2017 10:32:19 +0100
+Subject: [PATCH 122/454] amba_pl011: Add cts-event-workaround DT property
+
+The BCM2835 PL011 implementation seems to have a bug that can lead to a
+transmission lockup if CTS changes frequently. A workaround was added to
+the driver with a vendor-specific flag to enable it, but this flag is
+currently not set for ARM implementations.
+
+Add a "cts-event-workaround" property to Pi DTBs and use the presence
+of that property to force the flag to be enabled in the driver.
+
+See: https://github.com/raspberrypi/linux/issues/1280
+
+Signed-off-by: Phil Elwell <phil@raspberrypi.org>
+---
+ Documentation/devicetree/bindings/serial/pl011.txt | 3 +++
+ drivers/tty/serial/amba-pl011.c | 5 +++++
+ 2 files changed, 8 insertions(+)
+
+--- a/Documentation/devicetree/bindings/serial/pl011.txt
++++ b/Documentation/devicetree/bindings/serial/pl011.txt
+@@ -35,6 +35,9 @@ Optional properties:
+ - poll-timeout-ms:
+ Poll timeout when auto-poll is set, default
+ 3000ms.
++- cts-event-workaround:
++ Enables the (otherwise vendor-specific) workaround for the
++ CTS-induced TX lockup.
+
+ See also bindings/arm/primecell.txt
+
+--- a/drivers/tty/serial/amba-pl011.c
++++ b/drivers/tty/serial/amba-pl011.c
+@@ -2681,6 +2681,11 @@ static int pl011_probe(struct amba_devic
+ if (IS_ERR(uap->clk))
+ return PTR_ERR(uap->clk);
+
++ if (of_property_read_bool(dev->dev.of_node, "cts-event-workaround")) {
++ vendor->cts_event_workaround = true;
++ dev_info(&dev->dev, "cts_event_workaround enabled\n");
++ }
++
+ uap->reg_offset = vendor->reg_offset;
+ uap->vendor = vendor;
+ uap->fifosize = vendor->get_fifosize(dev);