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/cpufreq/speedstep-lib.h | 48 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48 insertions(+) create mode 100644 drivers/cpufreq/speedstep-lib.h (limited to 'drivers/cpufreq/speedstep-lib.h') diff --git a/drivers/cpufreq/speedstep-lib.h b/drivers/cpufreq/speedstep-lib.h new file mode 100644 index 000000000..48329647d --- /dev/null +++ b/drivers/cpufreq/speedstep-lib.h @@ -0,0 +1,48 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * (C) 2002 - 2003 Dominik Brodowski + * + * Library for common functions for Intel SpeedStep v.1 and v.2 support + * + * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous* + */ + + + +/* processors */ +enum speedstep_processor { + SPEEDSTEP_CPU_PIII_C_EARLY = 0x00000001, /* Coppermine core */ + SPEEDSTEP_CPU_PIII_C = 0x00000002, /* Coppermine core */ + SPEEDSTEP_CPU_PIII_T = 0x00000003, /* Tualatin core */ + SPEEDSTEP_CPU_P4M = 0x00000004, /* P4-M */ +/* the following processors are not speedstep-capable and are not auto-detected + * in speedstep_detect_processor(). However, their speed can be detected using + * the speedstep_get_frequency() call. */ + SPEEDSTEP_CPU_PM = 0xFFFFFF03, /* Pentium M */ + SPEEDSTEP_CPU_P4D = 0xFFFFFF04, /* desktop P4 */ + SPEEDSTEP_CPU_PCORE = 0xFFFFFF05, /* Core */ +}; + +/* speedstep states -- only two of them */ + +#define SPEEDSTEP_HIGH 0x00000000 +#define SPEEDSTEP_LOW 0x00000001 + + +/* detect a speedstep-capable processor */ +extern enum speedstep_processor speedstep_detect_processor(void); + +/* detect the current speed (in khz) of the processor */ +extern unsigned int speedstep_get_frequency(enum speedstep_processor processor); + + +/* detect the low and high speeds of the processor. The callback + * set_state"'s first argument is either SPEEDSTEP_HIGH or + * SPEEDSTEP_LOW; the second argument is zero so that no + * cpufreq_notify_transition calls are initiated. + */ +extern int speedstep_get_freqs(enum speedstep_processor processor, + unsigned int *low_speed, + unsigned int *high_speed, + unsigned int *transition_latency, + void (*set_state)(unsigned int state)); -- cgit v1.3.1