[PATCH] drm/amd/display: Add debugfs entry for amdgpu_dm_visual_confirm

[Nicholas Kazlauskas]

[Why]
DC provides a few visual confirmation debug options that can be
dynamically changed at runtime to help debug surface programming issues
but we don't have any way to access it from userspace.

[How]
Add the amdgpu_dm_visual_confirm debugfs entry.
It accepts a string containing the DC visual confirm enum value.

Cc: Leo Li <sunpeng.li at amd.com>
Cc: Harry Wentland <harry.wentland at amd.com>
Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas at amd.com>
---
 .../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 77 ++++++++++++++++++-
 1 file changed, 75 insertions(+), 2 deletions(-)

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 4a55cde027cf..1d6bfb84d7cf 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
@@ -803,6 +803,65 @@ static ssize_t dtn_log_write(
 	return size;
 }
 
+/*
+ * Reads the DC visual confirm debug option value into the given buffer.
+ * Example usage: cat /sys/kernel/debug/dri/0/amdgpu_dm_visual_confirm
+ */
+static ssize_t visual_confirm_read(struct file *f, char __user *buf,
+				   size_t size, loff_t *pos)
+{
+	struct amdgpu_device *adev = file_inode(f)->i_private;
+	struct dc *dc = adev->dm.dc;
+	size_t to_copy = 0;
+	int len;
+	char tmp[16];
+
+	if (!buf || !size)
+		return -EINVAL;
+
+	len = snprintf(tmp, sizeof(tmp), "%d\n", dc->debug.visual_confirm);
+	if (len < 0 || len >= sizeof(tmp))
+		return -EINVAL;
+
+	if (*pos >= len)
+		return 0;
+
+	to_copy = len - *pos;
+	if (to_copy > size)
+		return 0;
+
+	if (copy_to_user(buf, tmp + *pos, to_copy))
+		return -EFAULT;
+
+	*pos += to_copy;
+
+	return to_copy;
+}
+
+/*
+ * Sets the DC visual confirm debug option from the given string.
+ * Example usage: echo 1 > /sys/kernel/debug/dri/0/amdgpu_visual_confirm
+ */
+static ssize_t visual_confirm_write(struct file *f, const char __user *buf,
+				    size_t size, loff_t *pos)
+{
+	struct amdgpu_device *adev = file_inode(f)->i_private;
+	struct dc *dc = adev->dm.dc;
+	int ret;
+	u16 val;
+
+	if (size == 0)
+		return 0;
+
+	ret = kstrtou16_from_user(buf, size, 0, &val);
+	if (ret)
+		return ret;
+
+	dc->debug.visual_confirm = val;
+
+	return size;
+}
+
 /*
  * Backlight at this moment.  Read only.
  * As written to display, taking ABM and backlight lut into account.
@@ -850,7 +909,12 @@ int dtn_debugfs_init(struct amdgpu_device *adev)
 		.write = dtn_log_write,
 		.llseek = default_llseek
 	};
-
+	static const struct file_operations visual_confirm_fops = {
+		.owner = THIS_MODULE,
+		.read = visual_confirm_read,
+		.write = visual_confirm_write,
+		.llseek = default_llseek
+	};
 	struct drm_minor *minor = adev->ddev->primary;
 	struct dentry *ent, *root = minor->debugfs_root;
 	int ret;
@@ -867,5 +931,14 @@ int dtn_debugfs_init(struct amdgpu_device *adev)
 		adev,
 		&dtn_log_fops);
 
-	return PTR_ERR_OR_ZERO(ent);
+	if (IS_ERR(ent))
+		return PTR_ERR(ent);
+
+	ent = debugfs_create_file("amdgpu_dm_visual_confirm", 0644, root, adev,
+				  &visual_confirm_fops);
+
+	if (IS_ERR(ent))
+		return PTR_ERR(ent);
+
+	return 0;
 }
-- 
2.17.1