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, 172 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/tsc40.c b/drivers/input/touchscreen/tsc40.c
new file mode 100644
index 000000000..2a28a309e
--- /dev/null
+++ b/drivers/input/touchscreen/tsc40.c
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * TSC-40 serial touchscreen driver. It should be compatible with
+ * TSC-10 and 25.
+ *
+ * Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+
+#define PACKET_LENGTH  5
+struct tsc_ser {
+	struct input_dev *dev;
+	struct serio *serio;
+	u32 idx;
+	unsigned char data[PACKET_LENGTH];
+	char phys[32];
+};
+
+static void tsc_process_data(struct tsc_ser *ptsc)
+{
+	struct input_dev *dev = ptsc->dev;
+	u8 *data = ptsc->data;
+	u32 x;
+	u32 y;
+
+	x = ((data[1] & 0x03) << 8) | data[2];
+	y = ((data[3] & 0x03) << 8) | data[4];
+
+	input_report_abs(dev, ABS_X, x);
+	input_report_abs(dev, ABS_Y, y);
+	input_report_key(dev, BTN_TOUCH, 1);
+
+	input_sync(dev);
+}
+
+static irqreturn_t tsc_interrupt(struct serio *serio,
+		unsigned char data, unsigned int flags)
+{
+	struct tsc_ser *ptsc = serio_get_drvdata(serio);
+	struct input_dev *dev = ptsc->dev;
+
+	ptsc->data[ptsc->idx] = data;
+	switch (ptsc->idx++) {
+	case 0:
+		if (unlikely((data & 0x3e) != 0x10)) {
+			dev_dbg(&serio->dev,
+				"unsynchronized packet start (0x%02x)\n", data);
+			ptsc->idx = 0;
+		} else if (!(data & 0x01)) {
+			input_report_key(dev, BTN_TOUCH, 0);
+			input_sync(dev);
+			ptsc->idx = 0;
+		}
+		break;
+
+	case 1:
+	case 3:
+		if (unlikely(data & 0xfc)) {
+			dev_dbg(&serio->dev,
+				"unsynchronized data 0x%02x at offset %d\n",
+				data, ptsc->idx - 1);
+			ptsc->idx = 0;
+		}
+		break;
+
+	case 4:
+		tsc_process_data(ptsc);
+		ptsc->idx = 0;
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int tsc_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct tsc_ser *ptsc;
+	struct input_dev *input_dev;
+	int error;
+
+	ptsc = kzalloc_obj(*ptsc);
+	input_dev = input_allocate_device();
+	if (!ptsc || !input_dev) {
+		error = -ENOMEM;
+		goto fail1;
+	}
+
+	ptsc->serio = serio;
+	ptsc->dev = input_dev;
+	scnprintf(ptsc->phys, sizeof(ptsc->phys), "%s/input0", serio->phys);
+
+	input_dev->name = "TSC-10/25/40 Serial TouchScreen";
+	input_dev->phys = ptsc->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_TSC40;
+	input_dev->id.product = 40;
+	input_dev->id.version = 0x0001;
+	input_dev->dev.parent = &serio->dev;
+
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+	__set_bit(BTN_TOUCH, input_dev->keybit);
+	input_set_abs_params(ptsc->dev, ABS_X, 0, 0x3ff, 0, 0);
+	input_set_abs_params(ptsc->dev, ABS_Y, 0, 0x3ff, 0, 0);
+
+	serio_set_drvdata(serio, ptsc);
+
+	error = serio_open(serio, drv);
+	if (error)
+		goto fail2;
+
+	error = input_register_device(ptsc->dev);
+	if (error)
+		goto fail3;
+
+	return 0;
+
+fail3:
+	serio_close(serio);
+fail2:
+	serio_set_drvdata(serio, NULL);
+fail1:
+	input_free_device(input_dev);
+	kfree(ptsc);
+	return error;
+}
+
+static void tsc_disconnect(struct serio *serio)
+{
+	struct tsc_ser *ptsc = serio_get_drvdata(serio);
+
+	serio_close(serio);
+
+	input_unregister_device(ptsc->dev);
+	kfree(ptsc);
+
+	serio_set_drvdata(serio, NULL);
+}
+
+static const struct serio_device_id tsc_serio_ids[] = {
+	{
+		.type   = SERIO_RS232,
+		.proto  = SERIO_TSC40,
+		.id     = SERIO_ANY,
+		.extra  = SERIO_ANY,
+	},
+	{ 0 }
+};
+MODULE_DEVICE_TABLE(serio, tsc_serio_ids);
+
+#define DRIVER_DESC    "TSC-10/25/40 serial touchscreen driver"
+
+static struct serio_driver tsc_drv = {
+	.driver	= {
+		.name   = "tsc40",
+	},
+	.description    = DRIVER_DESC,
+	.id_table	= tsc_serio_ids,
+	.interrupt      = tsc_interrupt,
+	.connect	= tsc_connect,
+	.disconnect     = tsc_disconnect,
+};
+
+module_serio_driver(tsc_drv);
+
+MODULE_AUTHOR("Sebastian Andrzej Siewior <bigeasy@linutronix.de>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL v2");