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, 140 insertions, 0 deletions

diff --git a/drivers/clocksource/timer-mediatek-cpux.c b/drivers/clocksource/timer-mediatek-cpux.c
new file mode 100644
index 000000000..a8e3df4c0
--- /dev/null
+++ b/drivers/clocksource/timer-mediatek-cpux.c
@@ -0,0 +1,140 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * MediaTek SoCs CPUX General Purpose Timer handling
+ *
+ * Based on timer-mediatek.c:
+ * Copyright (C) 2014 Matthias Brugger <matthias.bgg@gmail.com>
+ *
+ * Copyright (C) 2022 Collabora Ltd.
+ *                    AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+#include "timer-of.h"
+
+#define TIMER_SYNC_TICKS        3
+
+/* cpux mcusys wrapper */
+#define CPUX_CON_REG		0x0
+#define CPUX_IDX_REG		0x4
+
+/* cpux */
+#define CPUX_IDX_GLOBAL_CTRL	0x0
+ #define CPUX_ENABLE		BIT(0)
+ #define CPUX_CLK_DIV_MASK	GENMASK(10, 8)
+ #define CPUX_CLK_DIV1		BIT(8)
+ #define CPUX_CLK_DIV2		BIT(9)
+ #define CPUX_CLK_DIV4		BIT(10)
+#define CPUX_IDX_GLOBAL_IRQ	0x30
+
+static u32 mtk_cpux_readl(u32 reg_idx, struct timer_of *to)
+{
+	writel(reg_idx, timer_of_base(to) + CPUX_IDX_REG);
+	return readl(timer_of_base(to) + CPUX_CON_REG);
+}
+
+static void mtk_cpux_writel(u32 val, u32 reg_idx, struct timer_of *to)
+{
+	writel(reg_idx, timer_of_base(to) + CPUX_IDX_REG);
+	writel(val, timer_of_base(to) + CPUX_CON_REG);
+}
+
+static void mtk_cpux_set_irq(struct timer_of *to, bool enable)
+{
+	const unsigned long *irq_mask = cpumask_bits(cpu_possible_mask);
+	u32 val;
+
+	val = mtk_cpux_readl(CPUX_IDX_GLOBAL_IRQ, to);
+
+	if (enable)
+		val |= *irq_mask;
+	else
+		val &= ~(*irq_mask);
+
+	mtk_cpux_writel(val, CPUX_IDX_GLOBAL_IRQ, to);
+}
+
+static int mtk_cpux_clkevt_shutdown(struct clock_event_device *clkevt)
+{
+	/* Clear any irq */
+	mtk_cpux_set_irq(to_timer_of(clkevt), false);
+
+	/*
+	 * Disabling CPUXGPT timer will crash the platform, especially
+	 * if Trusted Firmware is using it (usually, for sleep states),
+	 * so we only mask the IRQ and call it a day.
+	 */
+	return 0;
+}
+
+static int mtk_cpux_clkevt_resume(struct clock_event_device *clkevt)
+{
+	mtk_cpux_set_irq(to_timer_of(clkevt), true);
+	return 0;
+}
+
+static struct timer_of to = {
+	/*
+	 * There are per-cpu interrupts for the CPUX General Purpose Timer
+	 * but since this timer feeds the AArch64 System Timer we can rely
+	 * on the CPU timer PPIs as well, so we don't declare TIMER_OF_IRQ.
+	 */
+	.flags = TIMER_OF_BASE | TIMER_OF_CLOCK,
+
+	.clkevt = {
+		.name = "mtk-cpuxgpt",
+		.cpumask = cpu_possible_mask,
+		.rating = 10,
+		.set_state_shutdown = mtk_cpux_clkevt_shutdown,
+		.tick_resume = mtk_cpux_clkevt_resume,
+	},
+};
+
+static int __init mtk_cpux_init(struct device_node *node)
+{
+	u32 freq, val;
+	int ret;
+
+	/* If this fails, bad things are about to happen... */
+	ret = timer_of_init(node, &to);
+	if (ret) {
+		WARN(1, "Cannot start CPUX timers.\n");
+		return ret;
+	}
+
+	/*
+	 * Check if we're given a clock with the right frequency for this
+	 * timer, otherwise warn but keep going with the setup anyway, as
+	 * that makes it possible to still boot the kernel, even though
+	 * it may not work correctly (random lockups, etc).
+	 * The reason behind this is that having an early UART may not be
+	 * possible for everyone and this gives a chance to retrieve kmsg
+	 * for eventual debugging even on consumer devices.
+	 */
+	freq = timer_of_rate(&to);
+	if (freq > 13000000)
+		WARN(1, "Requested unsupported timer frequency %u\n", freq);
+
+	/* Clock input is 26MHz, set DIV2 to achieve 13MHz clock */
+	val = mtk_cpux_readl(CPUX_IDX_GLOBAL_CTRL, &to);
+	val &= ~CPUX_CLK_DIV_MASK;
+	val |= CPUX_CLK_DIV2;
+	mtk_cpux_writel(val, CPUX_IDX_GLOBAL_CTRL, &to);
+
+	/* Enable all CPUXGPT timers */
+	val = mtk_cpux_readl(CPUX_IDX_GLOBAL_CTRL, &to);
+	mtk_cpux_writel(val | CPUX_ENABLE, CPUX_IDX_GLOBAL_CTRL, &to);
+
+	clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
+					TIMER_SYNC_TICKS, 0xffffffff);
+
+	return 0;
+}
+TIMER_OF_DECLARE(mtk_mt6795, "mediatek,mt6795-systimer", mtk_cpux_init);