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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
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>
This commit is contained in:
Phil Elwell
2017-09-29 10:32:19 +01:00
committed by Dom Cobley
parent b98ad15d12
commit ce02da2034
2 changed files with 11 additions and 0 deletions
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6
Documentation/devicetree/bindings/serial/pl011.yaml
View File

@@ -104,6 +104,12 @@ properties:
on the device. on the device.
enum: [1, 4] enum: [1, 4]
cts-event-workaround:
description:
Enables the (otherwise vendor-specific) workaround for the
CTS-induced TX lockup.
type: boolean
required: required:
- compatible - compatible
- reg - reg

5
drivers/tty/serial/amba-pl011.c
View File

@@ -2895,6 +2895,11 @@ static int pl011_probe(struct amba_device *dev, const struct amba_id *id)
if (IS_ERR(uap->clk)) if (IS_ERR(uap->clk))
return PTR_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->reg_offset = vendor->reg_offset;
uap->vendor = vendor; uap->vendor = vendor;
uap->fifosize = vendor->get_fifosize(dev); uap->fifosize = vendor->get_fifosize(dev);