From 106b4a2a78b2a2f14885604891957b84bba502db Mon Sep 17 00:00:00 2001 From: Adrian Betschart Date: Fri, 11 Sep 2026 17:13:14 +0200 Subject: drm/amd/display: Try RGB before YCbCr 4:4:4 in stream validation 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 Assisted-by: Claude Code:claude-fable-5-1 Signed-off-by: Adrian Betschart Reviewed-by: Fangzhi Zuo Tested-by: Adolfo Rodrigues Tested-by: Daniel Wheeler Signed-off-by: Alex Deucher (cherry picked from commit 7de432bc753133764dc40d37f9388da56de251e7) --- drivers/md/dm-ps-queue-length.c | 286 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 286 insertions(+) create mode 100644 drivers/md/dm-ps-queue-length.c (limited to 'drivers/md/dm-ps-queue-length.c') diff --git a/drivers/md/dm-ps-queue-length.c b/drivers/md/dm-ps-queue-length.c new file mode 100644 index 000000000..4afea160a --- /dev/null +++ b/drivers/md/dm-ps-queue-length.c @@ -0,0 +1,286 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2004-2005 IBM Corp. All Rights Reserved. + * Copyright (C) 2006-2009 NEC Corporation. + * + * dm-queue-length.c + * + * Module Author: Stefan Bader, IBM + * Modified by: Kiyoshi Ueda, NEC + * + * This file is released under the GPL. + * + * queue-length path selector - choose a path with the least number of + * in-flight I/Os. + */ + +#include "dm.h" +#include "dm-path-selector.h" + +#include +#include +#include +#include +#include + +#define DM_MSG_PREFIX "multipath queue-length" +#define QL_MIN_IO 1 +#define QL_VERSION "0.2.0" + +struct selector { + struct list_head valid_paths; + struct list_head failed_paths; + spinlock_t lock; +}; + +struct path_info { + struct list_head list; + struct dm_path *path; + unsigned int repeat_count; + atomic_t qlen; /* the number of in-flight I/Os */ +}; + +static struct selector *alloc_selector(void) +{ + struct selector *s = kmalloc_obj(*s); + + if (s) { + INIT_LIST_HEAD(&s->valid_paths); + INIT_LIST_HEAD(&s->failed_paths); + spin_lock_init(&s->lock); + } + + return s; +} + +static int ql_create(struct path_selector *ps, unsigned int argc, char **argv) +{ + struct selector *s = alloc_selector(); + + if (!s) + return -ENOMEM; + + ps->context = s; + return 0; +} + +static void ql_free_paths(struct list_head *paths) +{ + struct path_info *pi, *next; + + list_for_each_entry_safe(pi, next, paths, list) { + list_del(&pi->list); + kfree(pi); + } +} + +static void ql_destroy(struct path_selector *ps) +{ + struct selector *s = ps->context; + + ql_free_paths(&s->valid_paths); + ql_free_paths(&s->failed_paths); + kfree(s); + ps->context = NULL; +} + +static int ql_status(struct path_selector *ps, struct dm_path *path, + status_type_t type, char *result, unsigned int maxlen) +{ + unsigned int sz = 0; + struct path_info *pi; + + /* When called with NULL path, return selector status/args. */ + if (!path) + DMEMIT("0 "); + else { + pi = path->pscontext; + + switch (type) { + case STATUSTYPE_INFO: + DMEMIT("%d ", atomic_read(&pi->qlen)); + break; + case STATUSTYPE_TABLE: + DMEMIT("%u ", pi->repeat_count); + break; + case STATUSTYPE_IMA: + *result = '\0'; + break; + } + } + + return sz; +} + +static int ql_add_path(struct path_selector *ps, struct dm_path *path, + int argc, char **argv, char **error) +{ + struct selector *s = ps->context; + struct path_info *pi; + unsigned int repeat_count = QL_MIN_IO; + char dummy; + unsigned long flags; + + /* + * Arguments: [] + * : The number of I/Os before switching path. + * If not given, default (QL_MIN_IO) is used. + */ + if (argc > 1) { + *error = "queue-length ps: incorrect number of arguments"; + return -EINVAL; + } + + if ((argc == 1) && (sscanf(argv[0], "%u%c", &repeat_count, &dummy) != 1)) { + *error = "queue-length ps: invalid repeat count"; + return -EINVAL; + } + + if (repeat_count > 1) { + DMWARN_LIMIT("repeat_count > 1 is deprecated, using 1 instead"); + repeat_count = 1; + } + + /* Allocate the path information structure */ + pi = kmalloc_obj(*pi); + if (!pi) { + *error = "queue-length ps: Error allocating path information"; + return -ENOMEM; + } + + pi->path = path; + pi->repeat_count = repeat_count; + atomic_set(&pi->qlen, 0); + + path->pscontext = pi; + + spin_lock_irqsave(&s->lock, flags); + list_add_tail(&pi->list, &s->valid_paths); + spin_unlock_irqrestore(&s->lock, flags); + + return 0; +} + +static void ql_fail_path(struct path_selector *ps, struct dm_path *path) +{ + struct selector *s = ps->context; + struct path_info *pi = path->pscontext; + unsigned long flags; + + spin_lock_irqsave(&s->lock, flags); + list_move(&pi->list, &s->failed_paths); + spin_unlock_irqrestore(&s->lock, flags); +} + +static int ql_reinstate_path(struct path_selector *ps, struct dm_path *path) +{ + struct selector *s = ps->context; + struct path_info *pi = path->pscontext; + unsigned long flags; + + spin_lock_irqsave(&s->lock, flags); + list_move_tail(&pi->list, &s->valid_paths); + spin_unlock_irqrestore(&s->lock, flags); + + return 0; +} + +/* + * Select a path having the minimum number of in-flight I/Os + */ +static struct dm_path *ql_select_path(struct path_selector *ps, size_t nr_bytes) +{ + struct selector *s = ps->context; + struct path_info *pi = NULL, *best = NULL; + struct dm_path *ret = NULL; + unsigned long flags; + + spin_lock_irqsave(&s->lock, flags); + if (list_empty(&s->valid_paths)) + goto out; + + list_for_each_entry(pi, &s->valid_paths, list) { + if (!best || + (atomic_read(&pi->qlen) < atomic_read(&best->qlen))) + best = pi; + + if (!atomic_read(&best->qlen)) + break; + } + + if (!best) + goto out; + + /* Move most recently used to least preferred to evenly balance. */ + list_move_tail(&best->list, &s->valid_paths); + + ret = best->path; +out: + spin_unlock_irqrestore(&s->lock, flags); + return ret; +} + +static int ql_start_io(struct path_selector *ps, struct dm_path *path, + size_t nr_bytes) +{ + struct path_info *pi = path->pscontext; + + atomic_inc(&pi->qlen); + + return 0; +} + +static int ql_end_io(struct path_selector *ps, struct dm_path *path, + size_t nr_bytes, u64 start_time) +{ + struct path_info *pi = path->pscontext; + + atomic_dec(&pi->qlen); + + return 0; +} + +static struct path_selector_type ql_ps = { + .name = "queue-length", + .module = THIS_MODULE, + .table_args = 1, + .info_args = 1, + .create = ql_create, + .destroy = ql_destroy, + .status = ql_status, + .add_path = ql_add_path, + .fail_path = ql_fail_path, + .reinstate_path = ql_reinstate_path, + .select_path = ql_select_path, + .start_io = ql_start_io, + .end_io = ql_end_io, +}; + +static int __init dm_ql_init(void) +{ + int r = dm_register_path_selector(&ql_ps); + + if (r < 0) { + DMERR("register failed %d", r); + return r; + } + + DMINFO("version " QL_VERSION " loaded"); + + return r; +} + +static void __exit dm_ql_exit(void) +{ + dm_unregister_path_selector(&ql_ps); +} + +module_init(dm_ql_init); +module_exit(dm_ql_exit); + +MODULE_AUTHOR("Stefan Bader "); +MODULE_DESCRIPTION( + "(C) Copyright IBM Corp. 2004,2005 All Rights Reserved.\n" + DM_NAME " path selector to balance the number of in-flight I/Os" +); +MODULE_LICENSE("GPL"); -- cgit v1.3.1