Re: [PATCH v2] drm/amd/display: add a debugfs interface for the DMUB trace mask
From: Aurabindo Pillai
Date: Mon Nov 13 2023 - 11:22:23 EST
On 11/13/2023 9:56 AM, Hamza Mahfooz wrote:
For features that are implemented primarily in DMUB (e.g. PSR), it is
useful to be able to trace them at a DMUB level from the kernel,
especially when debugging issues. So, introduce a debugfs interface that
is able to read and set the DMUB trace mask dynamically at runtime and
document how to use it.
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Mario Limonciello <mario.limonciello@xxxxxxx>
Signed-off-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
---
v2: only return -ETIMEDOUT for DMUB_STATUS_TIMEOUT
---
Documentation/gpu/amdgpu/display/dc-debug.rst | 41 ++++++++
.../gpu/amdgpu/display/trace-groups-table.csv | 29 ++++++
.../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 97 +++++++++++++++++++
.../gpu/drm/amd/display/dmub/inc/dmub_cmd.h | 40 +++++++-
4 files changed, 205 insertions(+), 2 deletions(-)
create mode 100644 Documentation/gpu/amdgpu/display/trace-groups-table.csv
diff --git a/Documentation/gpu/amdgpu/display/dc-debug.rst b/Documentation/gpu/amdgpu/display/dc-debug.rst
index 40c55a618918..817631b1dbf3 100644
--- a/Documentation/gpu/amdgpu/display/dc-debug.rst
+++ b/Documentation/gpu/amdgpu/display/dc-debug.rst
@@ -75,3 +75,44 @@ change in real-time by using something like::
When reporting a bug related to DC, consider attaching this log before and
after you reproduce the bug.
+
+DMUB Firmware Debug
+===================
+
+Sometimes, dmesg logs aren't enough. This is especially true if a feature is
+implemented primarily in DMUB firmware. In such cases, all we see in dmesg when
+an issue arises is some generic timeout error. So, to get more relevant
+information, we can trace DMUB commands by enabling the relevant bits in
+`amdgpu_dm_dmub_trace_mask`.
+
+Currently, we support the tracing of the following groups:
+
+Trace Groups
+------------
+
+.. csv-table::
+ :header-rows: 1
+ :widths: 1, 1
+ :file: ./trace-groups-table.csv
+
+**Note: Not all ASICs support all of the listed trace groups**
+
+So, to enable just PSR tracing you can use the following command::
+
+ # echo 0x8020 > /sys/kernel/debug/dri/0/amdgpu_dm_dmub_trace_mask
+
+Then, you need to enable logging trace events to the buffer, which you can do
+using the following::
+
+ # echo 1 > /sys/kernel/debug/dri/0/amdgpu_dm_dmcub_trace_event_en
+
+Lastly, after you are able to reproduce the issue you are trying to debug,
+you can disable tracing and read the trace log by using the following::
+
+ # echo 0 > /sys/kernel/debug/dri/0/amdgpu_dm_dmcub_trace_event_en
+ # cat /sys/kernel/debug/dri/0/amdgpu_dm_dmub_tracebuffer
+
+So, when reporting bugs related to features such as PSR and ABM, consider
+enabling the relevant bits in the mask before reproducing the issue and
+attach the log that you obtain from the trace buffer in any bug reports that you
+create.
diff --git a/Documentation/gpu/amdgpu/display/trace-groups-table.csv b/Documentation/gpu/amdgpu/display/trace-groups-table.csv
new file mode 100644
index 000000000000..3f6a50d1d883
--- /dev/null
+++ b/Documentation/gpu/amdgpu/display/trace-groups-table.csv
@@ -0,0 +1,29 @@
+Name, Mask Value
+INFO, 0x1
+IRQ SVC, 0x2
+VBIOS, 0x4
+REGISTER, 0x8
+PHY DBG, 0x10
+PSR, 0x20
+AUX, 0x40
+SMU, 0x80
+MALL, 0x100
+ABM, 0x200
+ALPM, 0x400
+TIMER, 0x800
+HW LOCK MGR, 0x1000
+INBOX1, 0x2000
+PHY SEQ, 0x4000
+PSR STATE, 0x8000
+ZSTATE, 0x10000
+TRANSMITTER CTL, 0x20000
+PANEL CNTL, 0x40000
+FAMS, 0x80000
+DPIA, 0x100000
+SUBVP, 0x200000
+INBOX0, 0x400000
+SDP, 0x4000000
+REPLAY, 0x8000000
+REPLAY RESIDENCY, 0x20000000
+CURSOR INFO, 0x80000000
+IPS, 0x100000000
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
index 45c972f2630d..67dea56cf583 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_debugfs.c
@@ -2971,6 +2971,100 @@ static int allow_edp_hotplug_detection_set(void *data, u64 val)
return 0;
}
+static int dmub_trace_mask_set(void *data, u64 val)
+{
+ struct amdgpu_device *adev = data;
+ struct dmub_srv *srv = adev->dm.dc->ctx->dmub_srv->dmub;
+ enum dmub_gpint_command cmd;
+ enum dmub_status status;
+ u64 mask = 0xffff;
+ u8 shift = 0;
+ u32 res;
+ int i;
+
+ if (!srv->fw_version)
+ return -EINVAL;
+
+ for (i = 0; i < 4; i++) {
+ res = (val & mask) >> shift;
+
+ switch (i) {
+ case 0:
+ cmd = DMUB_GPINT__SET_TRACE_BUFFER_MASK_WORD0;
+ break;
+ case 1:
+ cmd = DMUB_GPINT__SET_TRACE_BUFFER_MASK_WORD1;
+ break;
+ case 2:
+ cmd = DMUB_GPINT__SET_TRACE_BUFFER_MASK_WORD2;
+ break;
+ case 3:
+ cmd = DMUB_GPINT__SET_TRACE_BUFFER_MASK_WORD3;
+ break;
+ }
+
+ status = dmub_srv_send_gpint_command(srv, cmd, res, 30);
+
+ if (status == DMUB_STATUS_TIMEOUT)
+ return -ETIMEDOUT;
+ else if (status != DMUB_STATUS_OK)
+ return -EIO;
+
+ usleep_range(100, 1000);
+
+ mask <<= 16;
+ shift += 16;
+ }
+
+ return 0;
+}
+
+static int dmub_trace_mask_show(void *data, u64 *val)
+{
+ enum dmub_gpint_command cmd = DMUB_GPINT__GET_TRACE_BUFFER_MASK_WORD0;
+ struct amdgpu_device *adev = data;
+ struct dmub_srv *srv = adev->dm.dc->ctx->dmub_srv->dmub;
+ enum dmub_status status;
+ u8 shift = 0;
+ u64 raw = 0;
+ u64 res = 0;
+ int i = 0;
+
+ if (!srv->fw_version)
+ return -EINVAL;
+
+ while (i < 4) {
+ status = dmub_srv_send_gpint_command(srv, cmd, 0, 30);
+
+ if (status == DMUB_STATUS_OK) {
+ status = dmub_srv_get_gpint_response(srv, (u32 *) &raw);
+
+ if (status == DMUB_STATUS_TIMEOUT)
+ return -ETIMEDOUT;
+ else if (status != DMUB_STATUS_OK)
+ return -EIO;
+ } else if (status == DMUB_STATUS_TIMEOUT) {
+ return -ETIMEDOUT;
+ } else {
+ return -EIO;
+ }
+
+ usleep_range(100, 1000);
+
+ cmd++;
+ res |= (raw << shift);
+ shift += 16;
+ i++;
+ }
+
+ *val = res;
+
+ return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(dmub_trace_mask_fops, dmub_trace_mask_show,
+ dmub_trace_mask_set, "0x%llx\n");
+
/*
* Set dmcub trace event IRQ enable or disable.
* Usage to enable dmcub trace event IRQ: echo 1 > /sys/kernel/debug/dri/0/amdgpu_dm_dmcub_trace_event_en
@@ -3884,6 +3978,9 @@ void dtn_debugfs_init(struct amdgpu_device *adev)
debugfs_create_file_unsafe("amdgpu_dm_force_timing_sync", 0644, root,
adev, &force_timing_sync_ops);
+ debugfs_create_file_unsafe("amdgpu_dm_dmub_trace_mask", 0644, root,
+ adev, &dmub_trace_mask_fops);
+
debugfs_create_file_unsafe("amdgpu_dm_dmcub_trace_event_en", 0644, root,
adev, &dmcub_trace_event_state_fops);
diff --git a/drivers/gpu/drm/amd/display/dmub/inc/dmub_cmd.h b/drivers/gpu/drm/amd/display/dmub/inc/dmub_cmd.h
index ed4379c04715..aa6e6923afed 100644
--- a/drivers/gpu/drm/amd/display/dmub/inc/dmub_cmd.h
+++ b/drivers/gpu/drm/amd/display/dmub/inc/dmub_cmd.h
@@ -818,18 +818,54 @@ enum dmub_gpint_command {
* RETURN: Lower 32-bit mask.
*/
DMUB_GPINT__UPDATE_TRACE_BUFFER_MASK = 101,
+
/**
- * DESC: Updates the trace buffer lower 32-bit mask.
+ * DESC: Updates the trace buffer mask bit0~bit15.
* ARGS: The new mask
* RETURN: Lower 32-bit mask.
*/
DMUB_GPINT__SET_TRACE_BUFFER_MASK_WORD0 = 102,
+
/**
- * DESC: Updates the trace buffer mask bi0~bit15.
+ * DESC: Updates the trace buffer mask bit16~bit31.
* ARGS: The new mask
* RETURN: Lower 32-bit mask.
*/
DMUB_GPINT__SET_TRACE_BUFFER_MASK_WORD1 = 103,
+
+ /**
+ * DESC: Updates the trace buffer mask bit32~bit47.
+ * ARGS: The new mask
+ * RETURN: Lower 32-bit mask.
+ */
+ DMUB_GPINT__SET_TRACE_BUFFER_MASK_WORD2 = 114,
+
+ /**
+ * DESC: Updates the trace buffer mask bit48~bit63.
+ * ARGS: The new mask
+ * RETURN: Lower 32-bit mask.
+ */
+ DMUB_GPINT__SET_TRACE_BUFFER_MASK_WORD3 = 115,
+
+ /**
+ * DESC: Read the trace buffer mask bi0~bit15.
+ */
+ DMUB_GPINT__GET_TRACE_BUFFER_MASK_WORD0 = 116,
+
+ /**
+ * DESC: Read the trace buffer mask bit16~bit31.
+ */
+ DMUB_GPINT__GET_TRACE_BUFFER_MASK_WORD1 = 117,
+
+ /**
+ * DESC: Read the trace buffer mask bi32~bit47.
+ */
+ DMUB_GPINT__GET_TRACE_BUFFER_MASK_WORD2 = 118,
+
+ /**
+ * DESC: Updates the trace buffer mask bit32~bit63.
+ */
+ DMUB_GPINT__GET_TRACE_BUFFER_MASK_WORD3 = 119,
};
/**
Reviewed-by: Aurabindo Pillai <aurabindo.pillai@xxxxxxx>