diff options
Diffstat (limited to 'target/linux/bcm27xx/patches-4.19/950-0036-amba_pl011-Add-cts-event-workaround-DT-property.patch')
| -rw-r--r-- | target/linux/bcm27xx/patches-4.19/950-0036-amba_pl011-Add-cts-event-workaround-DT-property.patch | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/target/linux/bcm27xx/patches-4.19/950-0036-amba_pl011-Add-cts-event-workaround-DT-property.patch b/target/linux/bcm27xx/patches-4.19/950-0036-amba_pl011-Add-cts-event-workaround-DT-property.patch new file mode 100644 index 0000000000..d7514a5525 --- /dev/null +++ b/target/linux/bcm27xx/patches-4.19/950-0036-amba_pl011-Add-cts-event-workaround-DT-property.patch @@ -0,0 +1,47 @@ +From 17a4507175ca6018ea40e91c9d753bc39f043d99 Mon Sep 17 00:00:00 2001 +From: Phil Elwell <phil@raspberrypi.org> +Date: Fri, 29 Sep 2017 10:32:19 +0100 +Subject: [PATCH] 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 +@@ -2659,6 +2659,11 @@ 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); |