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, 205 insertions, 0 deletions

diff --git a/drivers/md/dm-vdo/wait-queue.c b/drivers/md/dm-vdo/wait-queue.c
new file mode 100644
index 000000000..f81ed0cee
--- /dev/null
+++ b/drivers/md/dm-vdo/wait-queue.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#include "wait-queue.h"
+
+#include <linux/device-mapper.h>
+
+#include "permassert.h"
+
+#include "status-codes.h"
+
+/**
+ * vdo_waitq_enqueue_waiter() - Add a waiter to the tail end of a waitq.
+ * @waitq: The vdo_wait_queue to which to add the waiter.
+ * @waiter: The waiter to add to the waitq.
+ *
+ * The waiter must not already be waiting in a waitq.
+ */
+void vdo_waitq_enqueue_waiter(struct vdo_wait_queue *waitq, struct vdo_waiter *waiter)
+{
+	BUG_ON(waiter->next_waiter != NULL);
+
+	if (waitq->last_waiter == NULL) {
+		/*
+		 * The waitq is empty, so form the initial circular list by self-linking the
+		 * initial waiter.
+		 */
+		waiter->next_waiter = waiter;
+	} else {
+		/* Splice the new waiter in at the end of the waitq. */
+		waiter->next_waiter = waitq->last_waiter->next_waiter;
+		waitq->last_waiter->next_waiter = waiter;
+	}
+
+	/* In both cases, the waiter we added to the list becomes the last waiter. */
+	waitq->last_waiter = waiter;
+	waitq->length += 1;
+}
+
+/**
+ * vdo_waitq_transfer_all_waiters() - Transfer all waiters from one waitq to
+ *                                    a second waitq, emptying the first waitq.
+ * @from_waitq: The waitq containing the waiters to move.
+ * @to_waitq: The waitq that will receive the waiters from the first waitq.
+ */
+void vdo_waitq_transfer_all_waiters(struct vdo_wait_queue *from_waitq,
+				    struct vdo_wait_queue *to_waitq)
+{
+	/* If the source waitq is empty, there's nothing to do. */
+	if (!vdo_waitq_has_waiters(from_waitq))
+		return;
+
+	if (vdo_waitq_has_waiters(to_waitq)) {
+		/*
+		 * Both are non-empty. Splice the two circular lists together
+		 * by swapping the next (head) pointers in the list tails.
+		 */
+		struct vdo_waiter *from_head = from_waitq->last_waiter->next_waiter;
+		struct vdo_waiter *to_head = to_waitq->last_waiter->next_waiter;
+
+		to_waitq->last_waiter->next_waiter = from_head;
+		from_waitq->last_waiter->next_waiter = to_head;
+	}
+
+	to_waitq->last_waiter = from_waitq->last_waiter;
+	to_waitq->length += from_waitq->length;
+	vdo_waitq_init(from_waitq);
+}
+
+/**
+ * vdo_waitq_notify_all_waiters() - Notify all the entries waiting in a waitq.
+ * @waitq: The vdo_wait_queue containing the waiters to notify.
+ * @callback: The function to call to notify each waiter, or NULL to invoke the callback field
+ *            registered in each waiter.
+ * @context: The context to pass to the callback function.
+ *
+ * Notifies all the entries waiting in a waitq to continue execution by invoking a callback
+ * function on each of them in turn. The waitq is copied and emptied before invoking any callbacks,
+ * and only the waiters that were in the waitq at the start of the call will be notified.
+ */
+void vdo_waitq_notify_all_waiters(struct vdo_wait_queue *waitq,
+				  vdo_waiter_callback_fn callback, void *context)
+{
+	/*
+	 * Copy and empty the waitq first, avoiding the possibility of an infinite
+	 * loop if entries are returned to the waitq by the callback function.
+	 */
+	struct vdo_wait_queue waiters;
+
+	vdo_waitq_init(&waiters);
+	vdo_waitq_transfer_all_waiters(waitq, &waiters);
+
+	/* Drain the copied waitq, invoking the callback on every entry. */
+	while (vdo_waitq_has_waiters(&waiters))
+		vdo_waitq_notify_next_waiter(&waiters, callback, context);
+}
+
+/**
+ * vdo_waitq_get_first_waiter() - Return the waiter that is at the head end of a waitq.
+ * @waitq: The vdo_wait_queue from which to get the first waiter.
+ *
+ * Return: The first (oldest) waiter in the waitq, or NULL if the waitq is empty.
+ */
+struct vdo_waiter *vdo_waitq_get_first_waiter(const struct vdo_wait_queue *waitq)
+{
+	struct vdo_waiter *last_waiter = waitq->last_waiter;
+
+	if (last_waiter == NULL) {
+		/* There are no waiters, so we're done. */
+		return NULL;
+	}
+
+	/* The waitq is circular, so the last entry links to the head of the waitq. */
+	return last_waiter->next_waiter;
+}
+
+/**
+ * vdo_waitq_dequeue_matching_waiters() - Remove all waiters that match based on the specified
+ *                                        matching method and append them to a vdo_wait_queue.
+ * @waitq: The vdo_wait_queue to process.
+ * @waiter_match: The method to determine matching.
+ * @match_context: Contextual info for the match method.
+ * @matched_waitq: A wait_waitq to store matches.
+ */
+void vdo_waitq_dequeue_matching_waiters(struct vdo_wait_queue *waitq,
+					vdo_waiter_match_fn waiter_match,
+					void *match_context,
+					struct vdo_wait_queue *matched_waitq)
+{
+	struct vdo_wait_queue iteration_waitq;
+
+	vdo_waitq_init(&iteration_waitq);
+	vdo_waitq_transfer_all_waiters(waitq, &iteration_waitq);
+
+	while (vdo_waitq_has_waiters(&iteration_waitq)) {
+		struct vdo_waiter *waiter = vdo_waitq_dequeue_waiter(&iteration_waitq);
+
+		vdo_waitq_enqueue_waiter((waiter_match(waiter, match_context) ?
+					  matched_waitq : waitq), waiter);
+	}
+}
+
+/**
+ * vdo_waitq_dequeue_waiter() - Remove the first (oldest) waiter from a waitq.
+ * @waitq: The vdo_wait_queue from which to remove the first entry.
+ *
+ * The caller will be responsible for waking the waiter by continuing its
+ * execution appropriately.
+ *
+ * Return: The first (oldest) waiter in the waitq, or NULL if the waitq is empty.
+ */
+struct vdo_waiter *vdo_waitq_dequeue_waiter(struct vdo_wait_queue *waitq)
+{
+	struct vdo_waiter *first_waiter = vdo_waitq_get_first_waiter(waitq);
+	struct vdo_waiter *last_waiter = waitq->last_waiter;
+
+	if (first_waiter == NULL)
+		return NULL;
+
+	if (first_waiter == last_waiter) {
+		/* The waitq has a single entry, so empty it by nulling the tail. */
+		waitq->last_waiter = NULL;
+	} else {
+		/*
+		 * The waitq has multiple waiters, so splice the first waiter out
+		 * of the circular waitq.
+		 */
+		last_waiter->next_waiter = first_waiter->next_waiter;
+	}
+
+	/* The waiter is no longer in a waitq. */
+	first_waiter->next_waiter = NULL;
+	waitq->length -= 1;
+
+	return first_waiter;
+}
+
+/**
+ * vdo_waitq_notify_next_waiter() - Notify the next entry waiting in a waitq.
+ * @waitq: The vdo_wait_queue containing the waiter to notify.
+ * @callback: The function to call to notify the waiter, or NULL to invoke the callback field
+ *            registered in the waiter.
+ * @context: The context to pass to the callback function.
+ *
+ * Notifies the next entry waiting in a waitq to continue execution by invoking a callback function
+ * on it after removing it from the waitq.
+ *
+ * Return: true if there was a waiter in the waitq.
+ */
+bool vdo_waitq_notify_next_waiter(struct vdo_wait_queue *waitq,
+				  vdo_waiter_callback_fn callback, void *context)
+{
+	struct vdo_waiter *waiter = vdo_waitq_dequeue_waiter(waitq);
+
+	if (waiter == NULL)
+		return false;
+
+	if (callback == NULL)
+		callback = waiter->callback;
+	callback(waiter, context);
+
+	return true;
+}