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, 160 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-ds1672.c b/drivers/rtc/rtc-ds1672.c
new file mode 100644
index 000000000..c610beb55
--- /dev/null
+++ b/drivers/rtc/rtc-ds1672.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * An rtc/i2c driver for the Dallas DS1672
+ * Copyright 2005-06 Tower Technologies
+ *
+ * Author: Alessandro Zummo <a.zummo@towertech.it>
+ */
+
+#include <linux/i2c.h>
+#include <linux/rtc.h>
+#include <linux/module.h>
+
+/* Registers */
+
+#define DS1672_REG_CNT_BASE	0
+#define DS1672_REG_CONTROL	4
+#define DS1672_REG_TRICKLE	5
+
+#define DS1672_REG_CONTROL_EOSC	0x80
+
+/*
+ * In the routines that deal directly with the ds1672 hardware, we use
+ * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch
+ * Time is set to UTC.
+ */
+static int ds1672_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	unsigned long time;
+	unsigned char addr = DS1672_REG_CONTROL;
+	unsigned char buf[4];
+
+	struct i2c_msg msgs[] = {
+		{/* setup read ptr */
+			.addr = client->addr,
+			.len = 1,
+			.buf = &addr
+		},
+		{/* read date */
+			.addr = client->addr,
+			.flags = I2C_M_RD,
+			.len = 1,
+			.buf = buf
+		},
+	};
+
+	/* read control register */
+	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+		dev_warn(&client->dev, "Unable to read the control register\n");
+		return -EIO;
+	}
+
+	if (buf[0] & DS1672_REG_CONTROL_EOSC) {
+		dev_warn(&client->dev, "Oscillator not enabled. Set time to enable.\n");
+		return -EINVAL;
+	}
+
+	addr = DS1672_REG_CNT_BASE;
+	msgs[1].len = 4;
+
+	/* read date registers */
+	if ((i2c_transfer(client->adapter, &msgs[0], 2)) != 2) {
+		dev_err(&client->dev, "%s: read error\n", __func__);
+		return -EIO;
+	}
+
+	dev_dbg(&client->dev,
+		"%s: raw read data - counters=%02x,%02x,%02x,%02x\n",
+		__func__, buf[0], buf[1], buf[2], buf[3]);
+
+	time = ((unsigned long)buf[3] << 24) | (buf[2] << 16) |
+	       (buf[1] << 8) | buf[0];
+
+	rtc_time64_to_tm(time, tm);
+
+	dev_dbg(&client->dev, "%s: tm is %ptR\n", __func__, tm);
+
+	return 0;
+}
+
+static int ds1672_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int xfer;
+	unsigned char buf[6];
+	unsigned long secs = rtc_tm_to_time64(tm);
+
+	buf[0] = DS1672_REG_CNT_BASE;
+	buf[1] = secs & 0x000000FF;
+	buf[2] = (secs & 0x0000FF00) >> 8;
+	buf[3] = (secs & 0x00FF0000) >> 16;
+	buf[4] = (secs & 0xFF000000) >> 24;
+	buf[5] = 0;		/* set control reg to enable counting */
+
+	xfer = i2c_master_send(client, buf, 6);
+	if (xfer != 6) {
+		dev_err(&client->dev, "%s: send: %d\n", __func__, xfer);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static const struct rtc_class_ops ds1672_rtc_ops = {
+	.read_time = ds1672_read_time,
+	.set_time = ds1672_set_time,
+};
+
+static int ds1672_probe(struct i2c_client *client)
+{
+	int err = 0;
+	struct rtc_device *rtc;
+
+	dev_dbg(&client->dev, "%s\n", __func__);
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	rtc = devm_rtc_allocate_device(&client->dev);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
+
+	rtc->ops = &ds1672_rtc_ops;
+	rtc->range_max = U32_MAX;
+
+	err = devm_rtc_register_device(rtc);
+	if (err)
+		return err;
+
+	i2c_set_clientdata(client, rtc);
+
+	return 0;
+}
+
+static const struct i2c_device_id ds1672_id[] = {
+	{ .name = "ds1672" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ds1672_id);
+
+static const __maybe_unused struct of_device_id ds1672_of_match[] = {
+	{ .compatible = "dallas,ds1672" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ds1672_of_match);
+
+static struct i2c_driver ds1672_driver = {
+	.driver = {
+		   .name = "rtc-ds1672",
+		   .of_match_table = of_match_ptr(ds1672_of_match),
+	},
+	.probe = ds1672_probe,
+	.id_table = ds1672_id,
+};
+
+module_i2c_driver(ds1672_driver);
+
+MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
+MODULE_DESCRIPTION("Dallas/Maxim DS1672 timekeeper driver");
+MODULE_LICENSE("GPL");