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, 235 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-max6900.c b/drivers/rtc/rtc-max6900.c
new file mode 100644
index 000000000..8ef6d0fcd
--- /dev/null
+++ b/drivers/rtc/rtc-max6900.c
@@ -0,0 +1,235 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * rtc class driver for the Maxim MAX6900 chip
+ *
+ * Copyright (c) 2007 MontaVista, Software, Inc.
+ *
+ * Author: Dale Farnsworth <dale@farnsworth.org>
+ *
+ * based on previously existing rtc class drivers
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/bcd.h>
+#include <linux/rtc.h>
+#include <linux/delay.h>
+
+/*
+ * register indices
+ */
+#define MAX6900_REG_SC			0	/* seconds      00-59 */
+#define MAX6900_REG_MN			1	/* minutes      00-59 */
+#define MAX6900_REG_HR			2	/* hours        00-23 */
+#define MAX6900_REG_DT			3	/* day of month 00-31 */
+#define MAX6900_REG_MO			4	/* month        01-12 */
+#define MAX6900_REG_DW			5	/* day of week   1-7  */
+#define MAX6900_REG_YR			6	/* year         00-99 */
+#define MAX6900_REG_CT			7	/* control */
+						/* register 8 is undocumented */
+#define MAX6900_REG_CENTURY		9	/* century */
+#define MAX6900_REG_LEN			10
+
+#define MAX6900_BURST_LEN		8	/* can burst r/w first 8 regs */
+
+#define MAX6900_REG_CT_WP		(1 << 7)	/* Write Protect */
+
+/*
+ * register read/write commands
+ */
+#define MAX6900_REG_CONTROL_WRITE	0x8e
+#define MAX6900_REG_CENTURY_WRITE	0x92
+#define MAX6900_REG_CENTURY_READ	0x93
+#define MAX6900_REG_RESERVED_READ	0x96
+#define MAX6900_REG_BURST_WRITE		0xbe
+#define MAX6900_REG_BURST_READ		0xbf
+
+#define MAX6900_IDLE_TIME_AFTER_WRITE	3	/* specification says 2.5 mS */
+
+static struct i2c_driver max6900_driver;
+
+static int max6900_i2c_read_regs(struct i2c_client *client, u8 *buf)
+{
+	u8 reg_burst_read[1] = { MAX6900_REG_BURST_READ };
+	u8 reg_century_read[1] = { MAX6900_REG_CENTURY_READ };
+	struct i2c_msg msgs[4] = {
+		{
+		 .addr = client->addr,
+		 .flags = 0,	/* write */
+		 .len = sizeof(reg_burst_read),
+		 .buf = reg_burst_read}
+		,
+		{
+		 .addr = client->addr,
+		 .flags = I2C_M_RD,
+		 .len = MAX6900_BURST_LEN,
+		 .buf = buf}
+		,
+		{
+		 .addr = client->addr,
+		 .flags = 0,	/* write */
+		 .len = sizeof(reg_century_read),
+		 .buf = reg_century_read}
+		,
+		{
+		 .addr = client->addr,
+		 .flags = I2C_M_RD,
+		 .len = sizeof(buf[MAX6900_REG_CENTURY]),
+		 .buf = &buf[MAX6900_REG_CENTURY]
+		 }
+	};
+	int rc;
+
+	rc = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (rc != ARRAY_SIZE(msgs)) {
+		dev_err(&client->dev, "%s: register read failed\n", __func__);
+		return -EIO;
+	}
+	return 0;
+}
+
+static int max6900_i2c_write_regs(struct i2c_client *client, u8 const *buf)
+{
+	u8 i2c_century_buf[1 + 1] = { MAX6900_REG_CENTURY_WRITE };
+	struct i2c_msg century_msgs[1] = {
+		{
+		 .addr = client->addr,
+		 .flags = 0,	/* write */
+		 .len = sizeof(i2c_century_buf),
+		 .buf = i2c_century_buf}
+	};
+	u8 i2c_burst_buf[MAX6900_BURST_LEN + 1] = { MAX6900_REG_BURST_WRITE };
+	struct i2c_msg burst_msgs[1] = {
+		{
+		 .addr = client->addr,
+		 .flags = 0,	/* write */
+		 .len = sizeof(i2c_burst_buf),
+		 .buf = i2c_burst_buf}
+	};
+	int rc;
+
+	/*
+	 * We have to make separate calls to i2c_transfer because of
+	 * the need to delay after each write to the chip.  Also,
+	 * we write the century byte first, since we set the write-protect
+	 * bit as part of the burst write.
+	 */
+	i2c_century_buf[1] = buf[MAX6900_REG_CENTURY];
+
+	rc = i2c_transfer(client->adapter, century_msgs,
+			  ARRAY_SIZE(century_msgs));
+	if (rc != ARRAY_SIZE(century_msgs))
+		goto write_failed;
+
+	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
+
+	memcpy(&i2c_burst_buf[1], buf, MAX6900_BURST_LEN);
+
+	rc = i2c_transfer(client->adapter, burst_msgs, ARRAY_SIZE(burst_msgs));
+	if (rc != ARRAY_SIZE(burst_msgs))
+		goto write_failed;
+	msleep(MAX6900_IDLE_TIME_AFTER_WRITE);
+
+	return 0;
+
+ write_failed:
+	dev_err(&client->dev, "%s: register write failed\n", __func__);
+	return -EIO;
+}
+
+static int max6900_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	int rc;
+	u8 regs[MAX6900_REG_LEN];
+
+	rc = max6900_i2c_read_regs(client, regs);
+	if (rc < 0)
+		return rc;
+
+	tm->tm_sec = bcd2bin(regs[MAX6900_REG_SC]);
+	tm->tm_min = bcd2bin(regs[MAX6900_REG_MN]);
+	tm->tm_hour = bcd2bin(regs[MAX6900_REG_HR] & 0x3f);
+	tm->tm_mday = bcd2bin(regs[MAX6900_REG_DT]);
+	tm->tm_mon = bcd2bin(regs[MAX6900_REG_MO]) - 1;
+	tm->tm_year = bcd2bin(regs[MAX6900_REG_YR]) +
+		      bcd2bin(regs[MAX6900_REG_CENTURY]) * 100 - 1900;
+	tm->tm_wday = bcd2bin(regs[MAX6900_REG_DW]);
+
+	return 0;
+}
+
+static int max6900_i2c_clear_write_protect(struct i2c_client *client)
+{
+	return i2c_smbus_write_byte_data(client, MAX6900_REG_CONTROL_WRITE, 0);
+}
+
+static int max6900_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	u8 regs[MAX6900_REG_LEN];
+	int rc;
+
+	rc = max6900_i2c_clear_write_protect(client);
+	if (rc < 0)
+		return rc;
+
+	regs[MAX6900_REG_SC] = bin2bcd(tm->tm_sec);
+	regs[MAX6900_REG_MN] = bin2bcd(tm->tm_min);
+	regs[MAX6900_REG_HR] = bin2bcd(tm->tm_hour);
+	regs[MAX6900_REG_DT] = bin2bcd(tm->tm_mday);
+	regs[MAX6900_REG_MO] = bin2bcd(tm->tm_mon + 1);
+	regs[MAX6900_REG_DW] = bin2bcd(tm->tm_wday);
+	regs[MAX6900_REG_YR] = bin2bcd(tm->tm_year % 100);
+	regs[MAX6900_REG_CENTURY] = bin2bcd((tm->tm_year + 1900) / 100);
+	/* set write protect */
+	regs[MAX6900_REG_CT] = MAX6900_REG_CT_WP;
+
+	rc = max6900_i2c_write_regs(client, regs);
+	if (rc < 0)
+		return rc;
+
+	return 0;
+}
+
+static const struct rtc_class_ops max6900_rtc_ops = {
+	.read_time = max6900_rtc_read_time,
+	.set_time = max6900_rtc_set_time,
+};
+
+static int max6900_probe(struct i2c_client *client)
+{
+	struct rtc_device *rtc;
+
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
+		return -ENODEV;
+
+	rtc = devm_rtc_device_register(&client->dev, max6900_driver.driver.name,
+					&max6900_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
+
+	i2c_set_clientdata(client, rtc);
+
+	return 0;
+}
+
+static const struct i2c_device_id max6900_id[] = {
+	{ .name = "max6900" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max6900_id);
+
+static struct i2c_driver max6900_driver = {
+	.driver = {
+		   .name = "rtc-max6900",
+		   },
+	.probe = max6900_probe,
+	.id_table = max6900_id,
+};
+
+module_i2c_driver(max6900_driver);
+
+MODULE_DESCRIPTION("Maxim MAX6900 RTC driver");
+MODULE_AUTHOR("Dale Farnsworth <dale@farnsworth.org>");
+MODULE_LICENSE("GPL");