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) --- lib/dump_stack.c | 131 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 131 insertions(+) create mode 100644 lib/dump_stack.c (limited to 'lib/dump_stack.c') diff --git a/lib/dump_stack.c b/lib/dump_stack.c new file mode 100644 index 000000000..f0c78b5b5 --- /dev/null +++ b/lib/dump_stack.c @@ -0,0 +1,131 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Provide a default dump_stack() function for architectures + * which don't implement their own. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static char dump_stack_arch_desc_str[128]; + +/** + * dump_stack_set_arch_desc - set arch-specific str to show with task dumps + * @fmt: printf-style format string + * @...: arguments for the format string + * + * The configured string will be printed right after utsname during task + * dumps. Usually used to add arch-specific system identifiers. If an + * arch wants to make use of such an ID string, it should initialize this + * as soon as possible during boot. + */ +void __init dump_stack_set_arch_desc(const char *fmt, ...) +{ + va_list args; + + va_start(args, fmt); + vsnprintf(dump_stack_arch_desc_str, sizeof(dump_stack_arch_desc_str), + fmt, args); + va_end(args); +} + +#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) +#define BUILD_ID_FMT " %20phN" +#define BUILD_ID_VAL vmlinux_build_id +#else +#define BUILD_ID_FMT "%s" +#define BUILD_ID_VAL "" +#endif + +/** + * dump_stack_print_info - print generic debug info for dump_stack() + * @log_lvl: log level + * + * Arch-specific dump_stack() implementations can use this function to + * print out the same debug information as the generic dump_stack(). + */ +void dump_stack_print_info(const char *log_lvl) +{ + printk("%sCPU: %d UID: %u PID: %d Comm: %.20s %s%s %s %.*s %s " BUILD_ID_FMT "\n", + log_lvl, raw_smp_processor_id(), + __kuid_val(current_real_cred()->euid), + current->pid, current->comm, + kexec_crash_loaded() ? "Kdump: loaded " : "", + print_tainted(), + init_utsname()->release, + (int)strcspn(init_utsname()->version, " "), + init_utsname()->version, preempt_model_str(), BUILD_ID_VAL); + + if (get_taint()) + printk("%s%s\n", log_lvl, print_tainted_verbose()); + + if (dump_stack_arch_desc_str[0] != '\0') + printk("%sHardware name: %s\n", + log_lvl, dump_stack_arch_desc_str); + + print_worker_info(log_lvl, current); + print_stop_info(log_lvl, current); + print_scx_info(log_lvl, current); +} + +/** + * show_regs_print_info - print generic debug info for show_regs() + * @log_lvl: log level + * + * show_regs() implementations can use this function to print out generic + * debug information. + */ +void show_regs_print_info(const char *log_lvl) +{ + dump_stack_print_info(log_lvl); +} + +static void __dump_stack(const char *log_lvl) +{ + dump_stack_print_info(log_lvl); + show_stack(NULL, NULL, log_lvl); +} + +/** + * dump_stack_lvl - dump the current task information and its stack trace + * @log_lvl: log level + * + * Architectures can override this implementation by implementing its own. + */ +asmlinkage __visible void dump_stack_lvl(const char *log_lvl) +{ + bool in_panic = panic_on_this_cpu(); + unsigned long flags; + + /* + * Permit this cpu to perform nested stack dumps while serialising + * against other CPUs, unless this CPU is in panic. + * + * When in panic, non-panic CPUs are not permitted to store new + * printk messages so there is no need to synchronize the output. + * This avoids potential deadlock in panic() if another CPU is + * holding and unable to release the printk_cpu_sync. + */ + if (!in_panic) + printk_cpu_sync_get_irqsave(flags); + + __dump_stack(log_lvl); + + if (!in_panic) + printk_cpu_sync_put_irqrestore(flags); +} +EXPORT_SYMBOL(dump_stack_lvl); + +asmlinkage __visible void dump_stack(void) +{ + dump_stack_lvl(KERN_DEFAULT); +} +EXPORT_SYMBOL(dump_stack); -- cgit v1.3.1