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)

3 files changed, 445 insertions, 0 deletions

diff --git a/Documentation/admin-guide/thermal/index.rst b/Documentation/admin-guide/thermal/index.rst
new file mode 100644
index 000000000..e48bc0a19
--- /dev/null
+++ b/Documentation/admin-guide/thermal/index.rst
@@ -0,0 +1,9 @@
+=================
+Thermal Subsystem
+=================
+
+.. toctree::
+   :maxdepth: 1
+
+   intel_powerclamp
+   intel_thermal_throttle
diff --git a/Documentation/admin-guide/thermal/intel_powerclamp.rst b/Documentation/admin-guide/thermal/intel_powerclamp.rst
new file mode 100644
index 000000000..08509b978
--- /dev/null
+++ b/Documentation/admin-guide/thermal/intel_powerclamp.rst
@@ -0,0 +1,345 @@
+=======================
+Intel Powerclamp Driver
+=======================
+
+By:
+  - Arjan van de Ven <arjan@linux.intel.com>
+  - Jacob Pan <jacob.jun.pan@linux.intel.com>
+
+.. Contents:
+
+	(*) Introduction
+	    - Goals and Objectives
+
+	(*) Theory of Operation
+	    - Idle Injection
+	    - Calibration
+
+	(*) Performance Analysis
+	    - Effectiveness and Limitations
+	    - Power vs Performance
+	    - Scalability
+	    - Calibration
+	    - Comparison with Alternative Techniques
+
+	(*) Usage and Interfaces
+	    - Generic Thermal Layer (sysfs)
+	    - Kernel APIs (TBD)
+
+	(*) Module Parameters
+
+INTRODUCTION
+============
+
+Consider the situation where a system’s power consumption must be
+reduced at runtime, due to power budget, thermal constraint, or noise
+level, and where active cooling is not preferred. Software managed
+passive power reduction must be performed to prevent the hardware
+actions that are designed for catastrophic scenarios.
+
+Currently, P-states, T-states (clock modulation), and CPU offlining
+are used for CPU throttling.
+
+On Intel CPUs, C-states provide effective power reduction, but so far
+they’re only used opportunistically, based on workload. With the
+development of intel_powerclamp driver, the method of synchronizing
+idle injection across all online CPU threads was introduced. The goal
+is to achieve forced and controllable C-state residency.
+
+Test/Analysis has been made in the areas of power, performance,
+scalability, and user experience. In many cases, clear advantage is
+shown over taking the CPU offline or modulating the CPU clock.
+
+
+THEORY OF OPERATION
+===================
+
+Idle Injection
+--------------
+
+On modern Intel processors (Nehalem or later), package level C-state
+residency is available in MSRs, thus also available to the kernel.
+
+These MSRs are::
+
+      #define MSR_PKG_C2_RESIDENCY      0x60D
+      #define MSR_PKG_C3_RESIDENCY      0x3F8
+      #define MSR_PKG_C6_RESIDENCY      0x3F9
+      #define MSR_PKG_C7_RESIDENCY      0x3FA
+
+If the kernel can also inject idle time to the system, then a
+closed-loop control system can be established that manages package
+level C-state. The intel_powerclamp driver is conceived as such a
+control system, where the target set point is a user-selected idle
+ratio (based on power reduction), and the error is the difference
+between the actual package level C-state residency ratio and the target idle
+ratio.
+
+Injection is controlled by high priority kernel threads, spawned for
+each online CPU.
+
+These kernel threads, with SCHED_FIFO class, are created to perform
+clamping actions of controlled duty ratio and duration. Each per-CPU
+thread synchronizes its idle time and duration, based on the rounding
+of jiffies, so accumulated errors can be prevented to avoid a jittery
+effect. Threads are also bound to the CPU such that they cannot be
+migrated, unless the CPU is taken offline. In this case, threads
+belong to the offlined CPUs will be terminated immediately.
+
+Running as SCHED_FIFO and relatively high priority, also allows such
+scheme to work for both preemptible and non-preemptible kernels.
+Alignment of idle time around jiffies ensures scalability for HZ
+values. This effect can be better visualized using a Perf timechart.
+The following diagram shows the behavior of kernel thread
+kidle_inject/cpu. During idle injection, it runs monitor/mwait idle
+for a given "duration", then relinquishes the CPU to other tasks,
+until the next time interval.
+
+The NOHZ schedule tick is disabled during idle time, but interrupts
+are not masked. Tests show that the extra wakeups from scheduler tick
+have a dramatic impact on the effectiveness of the powerclamp driver
+on large scale systems (Westmere system with 80 processors).
+
+::
+
+  CPU0
+		    ____________          ____________
+  kidle_inject/0   |   sleep    |  mwait |  sleep     |
+	  _________|            |________|            |_______
+				 duration
+  CPU1
+		    ____________          ____________
+  kidle_inject/1   |   sleep    |  mwait |  sleep     |
+	  _________|            |________|            |_______
+				^
+				|
+				|
+				roundup(jiffies, interval)
+
+Only one CPU is allowed to collect statistics and update global
+control parameters. This CPU is referred to as the controlling CPU in
+this document. The controlling CPU is elected at runtime, with a
+policy that favors BSP, taking into account the possibility of a CPU
+hot-plug.
+
+In terms of dynamics of the idle control system, package level idle
+time is considered largely as a non-causal system where its behavior
+cannot be based on the past or current input. Therefore, the
+intel_powerclamp driver attempts to enforce the desired idle time
+instantly as given input (target idle ratio). After injection,
+powerclamp monitors the actual idle for a given time window and adjust
+the next injection accordingly to avoid over/under correction.
+
+When used in a causal control system, such as a temperature control,
+it is up to the user of this driver to implement algorithms where
+past samples and outputs are included in the feedback. For example, a
+PID-based thermal controller can use the powerclamp driver to
+maintain a desired target temperature, based on integral and
+derivative gains of the past samples.
+
+
+
+Calibration
+-----------
+During scalability testing, it is observed that synchronized actions
+among CPUs become challenging as the number of cores grows. This is
+also true for the ability of a system to enter package level C-states.
+
+To make sure the intel_powerclamp driver scales well, online
+calibration is implemented. The goals for doing such a calibration
+are:
+
+a) determine the effective range of idle injection ratio
+b) determine the amount of compensation needed at each target ratio
+
+Compensation to each target ratio consists of two parts:
+
+	a) steady state error compensation
+
+	   This is to offset the error occurring when the system can
+	   enter idle without extra wakeups (such as external interrupts).
+
+	b) dynamic error compensation
+
+	   When an excessive amount of wakeups occurs during idle, an
+	   additional idle ratio can be added to quiet interrupts, by
+	   slowing down CPU activities.
+
+A debugfs file is provided for the user to examine compensation
+progress and results, such as on a Westmere system::
+
+  [jacob@nex01 ~]$ cat
+  /sys/kernel/debug/intel_powerclamp/powerclamp_calib
+  controlling cpu: 0
+  pct confidence steady dynamic (compensation)
+  0       0       0       0
+  1       1       0       0
+  2       1       1       0
+  3       3       1       0
+  4       3       1       0
+  5       3       1       0
+  6       3       1       0
+  7       3       1       0
+  8       3       1       0
+  ...
+  30      3       2       0
+  31      3       2       0
+  32      3       1       0
+  33      3       2       0
+  34      3       1       0
+  35      3       2       0
+  36      3       1       0
+  37      3       2       0
+  38      3       1       0
+  39      3       2       0
+  40      3       3       0
+  41      3       1       0
+  42      3       2       0
+  43      3       1       0
+  44      3       1       0
+  45      3       2       0
+  46      3       3       0
+  47      3       0       0
+  48      3       2       0
+  49      3       3       0
+
+Calibration occurs during runtime. No offline method is available.
+Steady state compensation is used only when confidence levels of all
+adjacent ratios have reached satisfactory level. A confidence level
+is accumulated based on clean data collected at runtime. Data
+collected during a period without extra interrupts is considered
+clean.
+
+To compensate for excessive amounts of wakeup during idle, additional
+idle time is injected when such a condition is detected. Currently,
+we have a simple algorithm to double the injection ratio. A possible
+enhancement might be to throttle the offending IRQ, such as delaying
+EOI for level triggered interrupts. But it is a challenge to be
+non-intrusive to the scheduler or the IRQ core code.
+
+
+CPU Online/Offline
+------------------
+Per-CPU kernel threads are started/stopped upon receiving
+notifications of CPU hotplug activities. The intel_powerclamp driver
+keeps track of clamping kernel threads, even after they are migrated
+to other CPUs, after a CPU offline event.
+
+
+Performance Analysis
+====================
+This section describes the general performance data collected on
+multiple systems, including Westmere (80P) and Ivy Bridge (4P, 8P).
+
+Effectiveness and Limitations
+-----------------------------
+The maximum range that idle injection is allowed is capped at 50
+percent. As mentioned earlier, since interrupts are allowed during
+forced idle time, excessive interrupts could result in less
+effectiveness. The extreme case would be doing a ping -f to generated
+flooded network interrupts without much CPU acknowledgement. In this
+case, little can be done from the idle injection threads. In most
+normal cases, such as scp a large file, applications can be throttled
+by the powerclamp driver, since slowing down the CPU also slows down
+network protocol processing, which in turn reduces interrupts.
+
+When control parameters change at runtime by the controlling CPU, it
+may take an additional period for the rest of the CPUs to catch up
+with the changes. During this time, idle injection is out of sync,
+thus not able to enter package C- states at the expected ratio. But
+this effect is minor, in that in most cases change to the target
+ratio is updated much less frequently than the idle injection
+frequency.
+
+Scalability
+-----------
+Tests also show a minor, but measurable, difference between the 4P/8P
+Ivy Bridge system and the 80P Westmere server under 50% idle ratio.
+More compensation is needed on Westmere for the same amount of
+target idle ratio. The compensation also increases as the idle ratio
+gets larger. The above reason constitutes the need for the
+calibration code.
+
+On the IVB 8P system, compared to an offline CPU, powerclamp can
+achieve up to 40% better performance per watt. (measured by a spin
+counter summed over per CPU counting threads spawned for all running
+CPUs).
+
+Usage and Interfaces
+====================
+The powerclamp driver is registered to the generic thermal layer as a
+cooling device. Currently, it’s not bound to any thermal zones::
+
+  jacob@chromoly:/sys/class/thermal/cooling_device14$ grep . *
+  cur_state:0
+  max_state:50
+  type:intel_powerclamp
+
+cur_state allows user to set the desired idle percentage. Writing 0 to
+cur_state will stop idle injection. Writing a value between 1 and
+max_state will start the idle injection. Reading cur_state returns the
+actual and current idle percentage. This may not be the same value
+set by the user in that current idle percentage depends on workload
+and includes natural idle. When idle injection is disabled, reading
+cur_state returns value -1 instead of 0 which is to avoid confusing
+100% busy state with the disabled state.
+
+Example usage:
+
+- To inject 25% idle time::
+
+	$ sudo sh -c "echo 25 > /sys/class/thermal/cooling_device80/cur_state
+
+If the system is not busy and has more than 25% idle time already,
+then the powerclamp driver will not start idle injection. Using Top
+will not show idle injection kernel threads.
+
+If the system is busy (spin test below) and has less than 25% natural
+idle time, powerclamp kernel threads will do idle injection. Forced
+idle time is accounted as normal idle in that common code path is
+taken as the idle task.
+
+In this example, 24.1% idle is shown. This helps the system admin or
+user determine the cause of slowdown, when a powerclamp driver is in action::
+
+
+  Tasks: 197 total,   1 running, 196 sleeping,   0 stopped,   0 zombie
+  Cpu(s): 71.2%us,  4.7%sy,  0.0%ni, 24.1%id,  0.0%wa,  0.0%hi,  0.0%si,  0.0%st
+  Mem:   3943228k total,  1689632k used,  2253596k free,    74960k buffers
+  Swap:  4087804k total,        0k used,  4087804k free,   945336k cached
+
+    PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
+   3352 jacob     20   0  262m  644  428 S  286  0.0   0:17.16 spin
+   3341 root     -51   0     0    0    0 D   25  0.0   0:01.62 kidle_inject/0
+   3344 root     -51   0     0    0    0 D   25  0.0   0:01.60 kidle_inject/3
+   3342 root     -51   0     0    0    0 D   25  0.0   0:01.61 kidle_inject/1
+   3343 root     -51   0     0    0    0 D   25  0.0   0:01.60 kidle_inject/2
+   2935 jacob     20   0  696m 125m  35m S    5  3.3   0:31.11 firefox
+   1546 root      20   0  158m  20m 6640 S    3  0.5   0:26.97 Xorg
+   2100 jacob     20   0 1223m  88m  30m S    3  2.3   0:23.68 compiz
+
+Tests have shown that by using the powerclamp driver as a cooling
+device, a PID based userspace thermal controller can manage to
+control CPU temperature effectively, when no other thermal influence
+is added. For example, a UltraBook user can compile the kernel under
+certain temperature (below most active trip points).
+
+Module Parameters
+=================
+
+``cpumask`` (RW)
+	A bit mask of CPUs to inject idle. The format of the bitmask is same as
+	used in other subsystems like in /proc/irq/\*/smp_affinity. The mask is
+	comma separated 32 bit groups. Each CPU is one bit. For example for a 256
+	CPU system the full mask is:
+	ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff
+
+	The rightmost mask is for CPU 0-32.
+
+``max_idle`` (RW)
+	Maximum injected idle time to the total CPU time ratio in percent range
+	from 1 to 100. Even if the cooling device max_state is always 100 (100%),
+	this parameter allows to add a max idle percent limit. The default is 50,
+	to match the current implementation of powerclamp driver. Also doesn't
+	allow value more than 75, if the cpumask includes every CPU present in
+	the system.
diff --git a/Documentation/admin-guide/thermal/intel_thermal_throttle.rst b/Documentation/admin-guide/thermal/intel_thermal_throttle.rst
new file mode 100644
index 000000000..f4fbf9d5a
--- /dev/null
+++ b/Documentation/admin-guide/thermal/intel_thermal_throttle.rst
@@ -0,0 +1,91 @@
+.. SPDX-License-Identifier: GPL-2.0
+.. include:: <isonum.txt>
+
+=======================================
+Intel thermal throttle events reporting
+=======================================
+
+:Author: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
+
+Introduction
+------------
+
+Intel processors have built in automatic and adaptive thermal monitoring
+mechanisms that force the processor to reduce its power consumption in order
+to operate within predetermined temperature limits.
+
+Refer to section "THERMAL MONITORING AND PROTECTION" in the "Intel® 64 and
+IA-32 Architectures Software Developer’s Manual Volume 3 (3A, 3B, 3C, & 3D):
+System Programming Guide" for more details.
+
+In general, there are two mechanisms to control the core temperature of the
+processor. They are called "Thermal Monitor 1 (TM1) and Thermal Monitor 2 (TM2)".
+
+The status of the temperature sensor that triggers the thermal monitor (TM1/TM2)
+is indicated through the "thermal status flag" and "thermal status log flag" in
+MSR_IA32_THERM_STATUS for core level and MSR_IA32_PACKAGE_THERM_STATUS for
+package level.
+
+Thermal Status flag, bit 0 — When set, indicates that the processor core
+temperature is currently at the trip temperature of the thermal monitor and that
+the processor power consumption is being reduced via either TM1 or TM2, depending
+on which is enabled. When clear, the flag indicates that the core temperature is
+below the thermal monitor trip temperature. This flag is read only.
+
+Thermal Status Log flag, bit 1 — When set, indicates that the thermal sensor has
+tripped since the last power-up or reset or since the last time that software
+cleared this flag. This flag is a sticky bit; once set it remains set until
+cleared by software or until a power-up or reset of the processor. The default
+state is clear.
+
+It is possible that when user reads MSR_IA32_THERM_STATUS or
+MSR_IA32_PACKAGE_THERM_STATUS, TM1/TM2 is not active. In this case,
+"Thermal Status flag" will read "0" and the "Thermal Status Log flag" will be set
+to show any previous "TM1/TM2" activation. But since it needs to be cleared by
+the software, it can't show the number of occurrences of "TM1/TM2" activations.
+
+Hence, Linux provides counters of how many times the "Thermal Status flag" was
+set. Also presents how long the "Thermal Status flag" was active in milliseconds.
+Using these counters, users can check if the performance was limited because of
+thermal events. It is recommended to read from sysfs instead of directly reading
+MSRs as the "Thermal Status Log flag" is reset by the driver to implement rate
+control.
+
+Sysfs Interface
+---------------
+
+Thermal throttling events are presented for each CPU under
+"/sys/devices/system/cpu/cpuX/thermal_throttle/", where "X" is the CPU number.
+
+All these counters are read-only. They can't be reset to 0. So, they can potentially
+overflow after reaching the maximum 64 bit unsigned integer.
+
+``core_throttle_count``
+	Shows the number of times "Thermal Status flag" changed from 0 to 1 for this
+	CPU since OS boot and thermal vector is initialized. This is a 64 bit counter.
+
+``package_throttle_count``
+	Shows the number of times "Thermal Status flag" changed from 0 to 1 for the
+	package containing this CPU since OS boot and thermal vector is initialized.
+	Package status is broadcast to all CPUs; all CPUs in the package increment
+	this count. This is a 64-bit counter.
+
+``core_throttle_max_time_ms``
+	Shows the maximum amount of time for which "Thermal Status flag" has been
+	set to 1 for this CPU at the core level since OS boot and thermal vector
+	is initialized.
+
+``package_throttle_max_time_ms``
+	Shows the maximum amount of time for which "Thermal Status flag" has been
+	set to 1 for the package containing this CPU since OS boot and thermal
+	vector is initialized.
+
+``core_throttle_total_time_ms``
+	Shows the cumulative time for which "Thermal Status flag" has been
+	set to 1 for this CPU for core level since OS boot and thermal vector
+	is initialized.
+
+``package_throttle_total_time_ms``
+	Shows the cumulative time for which "Thermal Status flag" has been set
+	to 1 for the package containing this CPU since OS boot and thermal vector
+	is initialized.