From 4352b8aee98005853aa63f57d6377282de17a33f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 23 Aug 2026 13:28:57 -0700 Subject: Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ... --- Documentation/gpu/amdgpu/debugging.rst | 105 +++++++++++++++++++++++++++++++++ 1 file changed, 105 insertions(+) create mode 100644 Documentation/gpu/amdgpu/debugging.rst (limited to 'Documentation/gpu/amdgpu/debugging.rst') diff --git a/Documentation/gpu/amdgpu/debugging.rst b/Documentation/gpu/amdgpu/debugging.rst new file mode 100644 index 000000000..ac914d524 --- /dev/null +++ b/Documentation/gpu/amdgpu/debugging.rst @@ -0,0 +1,105 @@ +=============== + GPU Debugging +=============== + +General Debugging Options +========================= + +The DebugFS section provides documentation on a number files to aid in debugging +issues on the GPU. + + +GPUVM Debugging +=============== + +To aid in debugging GPU virtual memory related problems, the driver supports a +number of options module parameters: + +`vm_fault_stop` - If non-0, halt the GPU memory controller on a GPU page fault. + +`vm_update_mode` - If non-0, use the CPU to update GPU page tables rather than +the GPU. + + +Decoding a GPUVM Page Fault +=========================== + +If you see a GPU page fault in the kernel log, you can decode it to figure +out what is going wrong in your application. A page fault in your kernel +log may look something like this: + +:: + + [gfxhub0] no-retry page fault (src_id:0 ring:24 vmid:3 pasid:32777, for process glxinfo pid 2424 thread glxinfo:cs0 pid 2425) + in page starting at address 0x0000800102800000 from IH client 0x1b (UTCL2) + VM_L2_PROTECTION_FAULT_STATUS:0x00301030 + Faulty UTCL2 client ID: TCP (0x8) + MORE_FAULTS: 0x0 + WALKER_ERROR: 0x0 + PERMISSION_FAULTS: 0x3 + MAPPING_ERROR: 0x0 + RW: 0x0 + +First you have the memory hub, gfxhub and mmhub. gfxhub is the memory +hub used for graphics, compute, and sdma on some chips. mmhub is the +memory hub used for multi-media and sdma on some chips. + +Next you have the vmid and pasid. If the vmid is 0, this fault was likely +caused by the kernel driver or firmware. If the vmid is non-0, it is generally +a fault in a user application. The pasid is used to link a vmid to a system +process id. If the process is active when the fault happens, the process +information will be printed. + +The GPU virtual address that caused the fault comes next. + +The client ID indicates the GPU block that caused the fault. +Some common client IDs: + +- CB/DB: The color/depth backend of the graphics pipe +- CPF: Command Processor Frontend +- CPC: Command Processor Compute +- CPG: Command Processor Graphics +- TCP/SQC/SQG: Shaders +- SDMA: SDMA engines +- VCN: Video encode/decode engines +- JPEG: JPEG engines + +PERMISSION_FAULTS describe what faults were encountered: + +- bit 0: the PTE was not valid +- bit 1: the PTE read bit was not set +- bit 2: the PTE write bit was not set +- bit 3: the PTE execute bit was not set + +Finally, RW, indicates whether the access was a read (0) or a write (1). + +In the example above, a shader (cliend id = TCP) generated a read (RW = 0x0) to +an invalid page (PERMISSION_FAULTS = 0x3) at GPU virtual address +0x0000800102800000. The user can then inspect their shader code and resource +descriptor state to determine what caused the GPU page fault. + +UMR +=== + +`umr `_ is a general purpose +GPU debugging and diagnostics tool. Please see the umr +`documentation `_ for more information +about its capabilities. + +Debugging backlight brightness +============================== +Default backlight brightness is intended to be set via the policy advertised +by the firmware. Firmware will often provide different defaults for AC or DC. +Furthermore, some userspace software will save backlight brightness during +the previous boot and attempt to restore it. + +Some firmware also has support for a feature called "Custom Backlight Curves" +where an input value for brightness is mapped along a linearly interpolated +curve of brightness values that better match display characteristics. + +In the event of problems happening with backlight, there is a trace event +that can be enabled at bootup to log every brightness change request. +This can help isolate where the problem is. To enable the trace event add +the following to the kernel command line: + + tp_printk trace_event=amdgpu_dm:amdgpu_dm_brightness:mod:amdgpu trace_buf_size=1M -- cgit v1.3.1