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, 193 insertions, 0 deletions

diff --git a/drivers/rtc/rtc-m48t35.c b/drivers/rtc/rtc-m48t35.c
new file mode 100644
index 000000000..92f19bf99
--- /dev/null
+++ b/drivers/rtc/rtc-m48t35.c
@@ -0,0 +1,193 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for the SGS-Thomson M48T35 Timekeeper RAM chip
+ *
+ * Copyright (C) 2000 Silicon Graphics, Inc.
+ * Written by Ulf Carlsson (ulfc@engr.sgi.com)
+ *
+ * Copyright (C) 2008 Thomas Bogendoerfer
+ *
+ * Based on code written by Paul Gortmaker.
+ */
+
+#include <linux/module.h>
+#include <linux/rtc.h>
+#include <linux/slab.h>
+#include <linux/platform_device.h>
+#include <linux/bcd.h>
+#include <linux/io.h>
+#include <linux/err.h>
+
+struct m48t35_rtc {
+	u8	pad[0x7ff8];    /* starts at 0x7ff8 */
+#ifdef CONFIG_SGI_IP27
+	u8	hour;
+	u8	min;
+	u8	sec;
+	u8	control;
+	u8	year;
+	u8	month;
+	u8	date;
+	u8	day;
+#else
+	u8	control;
+	u8	sec;
+	u8	min;
+	u8	hour;
+	u8	day;
+	u8	date;
+	u8	month;
+	u8	year;
+#endif
+};
+
+#define M48T35_RTC_SET		0x80
+#define M48T35_RTC_READ		0x40
+
+struct m48t35_priv {
+	struct rtc_device *rtc;
+	struct m48t35_rtc __iomem *reg;
+	size_t size;
+	unsigned long baseaddr;
+	spinlock_t lock;
+};
+
+static int m48t35_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct m48t35_priv *priv = dev_get_drvdata(dev);
+	u8 control;
+
+	/*
+	 * Only the values that we read from the RTC are set. We leave
+	 * tm_wday, tm_yday and tm_isdst untouched. Even though the
+	 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
+	 * by the RTC when initially set to a non-zero value.
+	 */
+	spin_lock_irq(&priv->lock);
+	control = readb(&priv->reg->control);
+	writeb(control | M48T35_RTC_READ, &priv->reg->control);
+	tm->tm_sec = readb(&priv->reg->sec);
+	tm->tm_min = readb(&priv->reg->min);
+	tm->tm_hour = readb(&priv->reg->hour);
+	tm->tm_mday = readb(&priv->reg->date);
+	tm->tm_mon = readb(&priv->reg->month);
+	tm->tm_year = readb(&priv->reg->year);
+	writeb(control, &priv->reg->control);
+	spin_unlock_irq(&priv->lock);
+
+	tm->tm_sec = bcd2bin(tm->tm_sec);
+	tm->tm_min = bcd2bin(tm->tm_min);
+	tm->tm_hour = bcd2bin(tm->tm_hour);
+	tm->tm_mday = bcd2bin(tm->tm_mday);
+	tm->tm_mon = bcd2bin(tm->tm_mon);
+	tm->tm_year = bcd2bin(tm->tm_year);
+
+	/*
+	 * Account for differences between how the RTC uses the values
+	 * and how they are defined in a struct rtc_time;
+	 */
+	tm->tm_year += 70;
+	if (tm->tm_year <= 69)
+		tm->tm_year += 100;
+
+	tm->tm_mon--;
+	return 0;
+}
+
+static int m48t35_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct m48t35_priv *priv = dev_get_drvdata(dev);
+	unsigned char mon, day, hrs, min, sec;
+	unsigned int yrs;
+	u8 control;
+
+	yrs = tm->tm_year + 1900;
+	mon = tm->tm_mon + 1;   /* tm_mon starts at zero */
+	day = tm->tm_mday;
+	hrs = tm->tm_hour;
+	min = tm->tm_min;
+	sec = tm->tm_sec;
+
+	if (yrs < 1970)
+		return -EINVAL;
+
+	yrs -= 1970;
+	if (yrs > 255)    /* They are unsigned */
+		return -EINVAL;
+
+	if (yrs > 169)
+		return -EINVAL;
+
+	if (yrs >= 100)
+		yrs -= 100;
+
+	sec = bin2bcd(sec);
+	min = bin2bcd(min);
+	hrs = bin2bcd(hrs);
+	day = bin2bcd(day);
+	mon = bin2bcd(mon);
+	yrs = bin2bcd(yrs);
+
+	spin_lock_irq(&priv->lock);
+	control = readb(&priv->reg->control);
+	writeb(control | M48T35_RTC_SET, &priv->reg->control);
+	writeb(yrs, &priv->reg->year);
+	writeb(mon, &priv->reg->month);
+	writeb(day, &priv->reg->date);
+	writeb(hrs, &priv->reg->hour);
+	writeb(min, &priv->reg->min);
+	writeb(sec, &priv->reg->sec);
+	writeb(control, &priv->reg->control);
+	spin_unlock_irq(&priv->lock);
+	return 0;
+}
+
+static const struct rtc_class_ops m48t35_ops = {
+	.read_time	= m48t35_read_time,
+	.set_time	= m48t35_set_time,
+};
+
+static int m48t35_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+	struct m48t35_priv *priv;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+	priv = devm_kzalloc(&pdev->dev, sizeof(struct m48t35_priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->size = resource_size(res);
+	if (!devm_request_mem_region(&pdev->dev, res->start, priv->size,
+				     pdev->name))
+		return -EBUSY;
+
+	priv->baseaddr = res->start;
+	priv->reg = devm_ioremap(&pdev->dev, priv->baseaddr, priv->size);
+	if (!priv->reg)
+		return -ENOMEM;
+
+	spin_lock_init(&priv->lock);
+
+	platform_set_drvdata(pdev, priv);
+
+	priv->rtc = devm_rtc_device_register(&pdev->dev, "m48t35",
+				  &m48t35_ops, THIS_MODULE);
+	return PTR_ERR_OR_ZERO(priv->rtc);
+}
+
+static struct platform_driver m48t35_platform_driver = {
+	.driver		= {
+		.name	= "rtc-m48t35",
+	},
+	.probe		= m48t35_probe,
+};
+
+module_platform_driver(m48t35_platform_driver);
+
+MODULE_AUTHOR("Thomas Bogendoerfer <tsbogend@alpha.franken.de>");
+MODULE_DESCRIPTION("M48T35 RTC driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:rtc-m48t35");