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From ca1ca821f735ad6284fa0c6228f27415e90f7a8f Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Fri, 29 Sep 2017 10:32:19 +0100
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Subject: [PATCH 122/454] amba_pl011: Add cts-event-workaround DT property
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The BCM2835 PL011 implementation seems to have a bug that can lead to a
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transmission lockup if CTS changes frequently. A workaround was added to
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the driver with a vendor-specific flag to enable it, but this flag is
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currently not set for ARM implementations.
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Add a "cts-event-workaround" property to Pi DTBs and use the presence
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of that property to force the flag to be enabled in the driver.
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See: https://github.com/raspberrypi/linux/issues/1280
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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Documentation/devicetree/bindings/serial/pl011.txt | 3 +++
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drivers/tty/serial/amba-pl011.c | 5 +++++
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2 files changed, 8 insertions(+)
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--- a/Documentation/devicetree/bindings/serial/pl011.txt
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+++ b/Documentation/devicetree/bindings/serial/pl011.txt
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@@ -35,6 +35,9 @@ Optional properties:
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- poll-timeout-ms:
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Poll timeout when auto-poll is set, default
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3000ms.
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+- cts-event-workaround:
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+ Enables the (otherwise vendor-specific) workaround for the
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+ CTS-induced TX lockup.
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See also bindings/arm/primecell.txt
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--- a/drivers/tty/serial/amba-pl011.c
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+++ b/drivers/tty/serial/amba-pl011.c
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@@ -2679,6 +2679,11 @@ static int pl011_probe(struct amba_devic
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if (IS_ERR(uap->clk))
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return PTR_ERR(uap->clk);
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+ if (of_property_read_bool(dev->dev.of_node, "cts-event-workaround")) {
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+ vendor->cts_event_workaround = true;
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+ dev_info(&dev->dev, "cts_event_workaround enabled\n");
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+ }
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+
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uap->reg_offset = vendor->reg_offset;
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uap->vendor = vendor;
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uap->fifosize = vendor->get_fifosize(dev);
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