drm/amd/display: Try RGB before YCbCr 4:4:4 in stream validationgrafted

amdgpu_dm_create_validate_stream_for_sink() walks encoding_order[] and
uses the first encoding that validates. YCbCr 4:4:4 is listed before
RGB, so an HDMI sink that advertises 4:4:4 gets YCbCr 4:4:4 whenever the
"color format" property is left at AUTO, even though RGB fits the same
link.

That contradicts the documented AUTO behaviour for HDMI in enum
drm_connector_color_format (RGB, falling back to YCbCr 4:2:0 only when
the bandwidth is not available or the mode is 4:2:0-only), which the
amdgpu implementation of the property also describes. It also leaves
the "Broadcast RGB" property without effect on such sinks, since the
quantization range it selects only applies to RGB output.

Try RGB first. The mask still holds every encoding the sink supports,
so a mode that cannot carry RGB falls back exactly as before.

For reference, v7.2 picked RGB here unless YCbCr 4:4:4 was forced
through debugfs, while earlier kernels picked YCbCr 4:4:4 for any HDMI
sink that advertised it.

Fixes: 0b0ff65d3ca1 ("drm/amd/display: Refactor stream validation")
Suggested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Assisted-by: Claude Code:claude-fable-5-1
Signed-off-by: Adrian Betschart <adrian.betschart@cinemaone.ch>
Reviewed-by: Fangzhi Zuo <jerry.zuo@amd.com>
Tested-by: Adolfo Rodrigues <adolfotregosa@gmail.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 7de432bc753133764dc40d37f9388da56de251e7)

1 files changed, 171 insertions, 0 deletions

diff --git a/drivers/usb/serial/bus.c b/drivers/usb/serial/bus.c
new file mode 100644
index 000000000..9e2a18c0b
--- /dev/null
+++ b/drivers/usb/serial/bus.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * USB Serial Converter Bus specific functions
+ *
+ * Copyright (C) 2002 Greg Kroah-Hartman (greg@kroah.com)
+ */
+
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/tty.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+#include <linux/usb/serial.h>
+
+static int usb_serial_device_match(struct device *dev,
+				   const struct device_driver *drv)
+{
+	const struct usb_serial_port *port = to_usb_serial_port(dev);
+	const struct usb_serial_driver *driver = to_usb_serial_driver(drv);
+
+	/*
+	 * drivers are already assigned to ports in serial_probe so it's
+	 * a simple check here.
+	 */
+	if (driver == port->serial->type)
+		return 1;
+
+	return 0;
+}
+
+static int usb_serial_device_probe(struct device *dev)
+{
+	struct usb_serial_port *port = to_usb_serial_port(dev);
+	struct usb_serial_driver *driver;
+	struct device *tty_dev;
+	int retval = 0;
+	int minor;
+
+	/* make sure suspend/resume doesn't race against port_probe */
+	retval = usb_autopm_get_interface(port->serial->interface);
+	if (retval)
+		return retval;
+
+	driver = port->serial->type;
+	if (driver->port_probe) {
+		retval = driver->port_probe(port);
+		if (retval)
+			goto err_autopm_put;
+	}
+
+	minor = port->minor;
+	tty_dev = tty_port_register_device(&port->port, usb_serial_tty_driver,
+					   minor, dev);
+	if (IS_ERR(tty_dev)) {
+		retval = PTR_ERR(tty_dev);
+		goto err_port_remove;
+	}
+
+	usb_autopm_put_interface(port->serial->interface);
+
+	dev_info(&port->serial->dev->dev,
+		 "%s converter now attached to ttyUSB%d\n",
+		 driver->description, minor);
+
+	return 0;
+
+err_port_remove:
+	if (driver->port_remove)
+		driver->port_remove(port);
+err_autopm_put:
+	usb_autopm_put_interface(port->serial->interface);
+
+	return retval;
+}
+
+static void usb_serial_device_remove(struct device *dev)
+{
+	struct usb_serial_port *port = to_usb_serial_port(dev);
+	struct usb_serial_driver *driver;
+	int minor;
+	int autopm_err;
+
+	/*
+	 * Make sure suspend/resume doesn't race against port_remove.
+	 *
+	 * Note that no further runtime PM callbacks will be made if
+	 * autopm_get fails.
+	 */
+	autopm_err = usb_autopm_get_interface(port->serial->interface);
+
+	minor = port->minor;
+	tty_unregister_device(usb_serial_tty_driver, minor);
+
+	driver = port->serial->type;
+	if (driver->port_remove)
+		driver->port_remove(port);
+
+	dev_info(dev, "%s converter now disconnected from ttyUSB%d\n",
+		 driver->description, minor);
+
+	if (!autopm_err)
+		usb_autopm_put_interface(port->serial->interface);
+}
+
+static ssize_t new_id_store(struct device_driver *driver,
+			    const char *buf, size_t count)
+{
+	struct usb_serial_driver *usb_drv = to_usb_serial_driver(driver);
+	ssize_t retval = usb_store_new_id(&usb_drv->dynids, usb_drv->id_table,
+					 driver, buf, count);
+
+	if (retval >= 0 && usb_drv->usb_driver != NULL)
+		retval = usb_store_new_id(&usb_drv->usb_driver->dynids,
+					  usb_drv->usb_driver->id_table,
+					  &usb_drv->usb_driver->driver,
+					  buf, count);
+	return retval;
+}
+
+static ssize_t new_id_show(struct device_driver *driver, char *buf)
+{
+	struct usb_serial_driver *usb_drv = to_usb_serial_driver(driver);
+
+	return usb_show_dynids(&usb_drv->dynids, buf);
+}
+static DRIVER_ATTR_RW(new_id);
+
+static struct attribute *usb_serial_drv_attrs[] = {
+	&driver_attr_new_id.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(usb_serial_drv);
+
+static void free_dynids(struct usb_serial_driver *drv)
+{
+	struct usb_dynid *dynid, *n;
+
+	guard(mutex)(&usb_dynids_lock);
+	list_for_each_entry_safe(dynid, n, &drv->dynids.list, node) {
+		list_del(&dynid->node);
+		kfree(dynid);
+	}
+}
+
+const struct bus_type usb_serial_bus_type = {
+	.name =		"usb-serial",
+	.match =	usb_serial_device_match,
+	.probe =	usb_serial_device_probe,
+	.remove =	usb_serial_device_remove,
+	.drv_groups = 	usb_serial_drv_groups,
+};
+
+int usb_serial_bus_register(struct usb_serial_driver *driver)
+{
+	int retval;
+
+	driver->driver.bus = &usb_serial_bus_type;
+	INIT_LIST_HEAD(&driver->dynids.list);
+
+	retval = driver_register(&driver->driver);
+
+	return retval;
+}
+
+void usb_serial_bus_deregister(struct usb_serial_driver *driver)
+{
+	free_dynids(driver);
+	driver_unregister(&driver->driver);
+}
+