Re: [PATCH v1] drm/amd/display: Add Debugfs Entry to Force in SST Sequence

[Kazlauskas, Nicholas]

On 2021-12-07 1:55 p.m., Fangzhi Zuo wrote:
It is w/a to check DP2 SST behavior on M42d box.

Isn't this useful beyond just the m42d/dp2?

This should affect regular DP MST support I think. Adding this debug 
flag is okay I think, but I think the names should be updated (inline).


Signed-off-by: Fangzhi Zuo <jerry....@amd.com>
---
  .../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 27 +++++++++++++++++++
  1 file changed, 27 insertions(+)

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 31c05eb5c64a..9590c0acba1f 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
@@ -3237,6 +3237,30 @@ static int disable_hpd_get(void *data, u64 *val)
  DEFINE_DEBUGFS_ATTRIBUTE(disable_hpd_ops, disable_hpd_get,
                         disable_hpd_set, "%llu\n");
  
+/*
+ * w/a to force in SST mode for M42D DP2 receiver.
+ * Example usage: echo 1 > /sys/kernel/debug/dri/0/amdgpu_dm_dp2_force_sst
+ */
+static int dp2_force_sst_set(void *data, u64 val)
+{
+       struct amdgpu_device *adev = data;
+
+       adev->dm.dc->debug.set_mst_en_for_sst = val;
+
+       return 0;
+}
+
+static int dp2_force_sst_get(void *data, u64 *val)
+{
+       struct amdgpu_device *adev = data;
+
+       *val = adev->dm.dc->debug.set_mst_en_for_sst;
+
+       return 0;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(dp2_force_sst_ops, dp2_force_sst_get,
+                        dp2_force_sst_set, "%llu\n");
+
  /*
   * Sets the DC visual confirm debug option from the given string.
   * Example usage: echo 1 > /sys/kernel/debug/dri/0/amdgpu_visual_confirm
@@ -3371,4 +3395,7 @@ void dtn_debugfs_init(struct amdgpu_device *adev)
        debugfs_create_file_unsafe("amdgpu_dm_disable_hpd", 0644, root, adev,
                                   &disable_hpd_ops);
  
+	debugfs_create_file_unsafe("amdgpu_dm_dp2_force_sst", 0644, root, adev,
+                                       &dp2_force_sst_ops);

"amdgpu_dm_dp_set_mst_en_for_sst"

...might be a better name.

Regards,
Nicholas Kazlauskas

+
  }