Re: [PATCH] drm/amd: Drop debugfs access to the DPCD

[Hamza Mahfooz]

On 5/24/23 13:58, Mario Limonciello wrote:

There is already access to the DPCD from userspace through
`CONFIG_DRM_DP_AUX_CHARDEV`, so it's unnecessary to reinvent the wheel
with a set of extra debugfs nodes specific to amdgpu.

The character device interface behaves more like you would expect in that
you can seek/read/write all from the same file.

Signed-off-by: Mario Limonciello <mario.limoncie...@amd.com>

Reviewed-by: Hamza Mahfooz <hamza.mahf...@amd.com>

---
  .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h |   4 -
  .../amd/display/amdgpu_dm/amdgpu_dm_debugfs.c | 107 ------------------
  2 files changed, 111 deletions(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h 
b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
index 2e2413fd73a4..4561f55afa99 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h
@@ -661,10 +661,6 @@ struct amdgpu_dm_connector {
        struct mutex hpd_lock;

bool fake_enable;

-#ifdef CONFIG_DEBUG_FS
-       uint32_t debugfs_dpcd_address;
-       uint32_t debugfs_dpcd_size;
-#endif
        bool force_yuv420_output;
        struct dsc_preferred_settings dsc_settings;
        union dp_downstream_port_present mst_downstream_port_present;
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 827fcb4fb3b3..82234397dd44 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
@@ -1039,88 +1039,6 @@ static ssize_t dp_sdp_message_debugfs_write(struct file 
*f, const char __user *b
        return write_size;
  }

-static ssize_t dp_dpcd_address_write(struct file *f, const char __user *buf,

-                                size_t size, loff_t *pos)
-{
-       int r;
-       struct amdgpu_dm_connector *connector = file_inode(f)->i_private;
-
-       if (size < sizeof(connector->debugfs_dpcd_address))
-               return -EINVAL;
-
-       r = copy_from_user(&connector->debugfs_dpcd_address,
-                       buf, sizeof(connector->debugfs_dpcd_address));
-
-       return size - r;
-}
-
-static ssize_t dp_dpcd_size_write(struct file *f, const char __user *buf,
-                                size_t size, loff_t *pos)
-{
-       int r;
-       struct amdgpu_dm_connector *connector = file_inode(f)->i_private;
-
-       if (size < sizeof(connector->debugfs_dpcd_size))
-               return -EINVAL;
-
-       r = copy_from_user(&connector->debugfs_dpcd_size,
-                       buf, sizeof(connector->debugfs_dpcd_size));
-
-       if (connector->debugfs_dpcd_size > 256)
-               connector->debugfs_dpcd_size = 0;
-
-       return size - r;
-}
-
-static ssize_t dp_dpcd_data_write(struct file *f, const char __user *buf,
-                                size_t size, loff_t *pos)
-{
-       int r;
-       char *data;
-       struct amdgpu_dm_connector *connector = file_inode(f)->i_private;
-       struct dc_link *link = connector->dc_link;
-       uint32_t write_size = connector->debugfs_dpcd_size;
-
-       if (!write_size || size < write_size)
-               return -EINVAL;
-
-       data = kzalloc(write_size, GFP_KERNEL);
-       if (!data)
-               return 0;
-
-       r = copy_from_user(data, buf, write_size);
-
-       dm_helpers_dp_write_dpcd(link->ctx, link,
-                       connector->debugfs_dpcd_address, data, write_size - r);
-       kfree(data);
-       return write_size - r;
-}
-
-static ssize_t dp_dpcd_data_read(struct file *f, char __user *buf,
-                                size_t size, loff_t *pos)
-{
-       int r;
-       char *data;
-       struct amdgpu_dm_connector *connector = file_inode(f)->i_private;
-       struct dc_link *link = connector->dc_link;
-       uint32_t read_size = connector->debugfs_dpcd_size;
-
-       if (!read_size || size < read_size)
-               return 0;
-
-       data = kzalloc(read_size, GFP_KERNEL);
-       if (!data)
-               return 0;
-
-       dm_helpers_dp_read_dpcd(link->ctx, link,
-                       connector->debugfs_dpcd_address, data, read_size);
-
-       r = copy_to_user(buf, data, read_size);
-
-       kfree(data);
-       return read_size - r;
-}
-
  /* function: Read link's DSC & FEC capabilities
   *
   *
@@ -2682,25 +2600,6 @@ static const struct file_operations sdp_message_fops = {
        .llseek = default_llseek
  };

-static const struct file_operations dp_dpcd_address_debugfs_fops = {

-       .owner = THIS_MODULE,
-       .write = dp_dpcd_address_write,
-       .llseek = default_llseek
-};
-
-static const struct file_operations dp_dpcd_size_debugfs_fops = {
-       .owner = THIS_MODULE,
-       .write = dp_dpcd_size_write,
-       .llseek = default_llseek
-};
-
-static const struct file_operations dp_dpcd_data_debugfs_fops = {
-       .owner = THIS_MODULE,
-       .read = dp_dpcd_data_read,
-       .write = dp_dpcd_data_write,
-       .llseek = default_llseek
-};
-
  static const struct file_operations dp_max_bpc_debugfs_fops = {
        .owner = THIS_MODULE,
        .read = dp_max_bpc_read,
@@ -2724,9 +2623,6 @@ static const struct {
                {"test_pattern", &dp_phy_test_pattern_fops},
                {"hdcp_sink_capability", &hdcp_sink_capability_fops},
                {"sdp_message", &sdp_message_fops},
-               {"aux_dpcd_address", &dp_dpcd_address_debugfs_fops},
-               {"aux_dpcd_size", &dp_dpcd_size_debugfs_fops},
-               {"aux_dpcd_data", &dp_dpcd_data_debugfs_fops},
                {"dsc_clock_en", &dp_dsc_clock_en_debugfs_fops},
                {"dsc_slice_width", &dp_dsc_slice_width_debugfs_fops},
                {"dsc_slice_height", &dp_dsc_slice_height_debugfs_fops},
@@ -3025,9 +2921,6 @@ void connector_debugfs_init(struct amdgpu_dm_connector 
*connector)
                                    connector_debugfs_entries[i].fops);
        }

- connector->debugfs_dpcd_address = 0;

-       connector->debugfs_dpcd_size = 0;
-
        if (connector->base.connector_type == DRM_MODE_CONNECTOR_HDMIA) {
                for (i = 0; i < ARRAY_SIZE(hdmi_debugfs_entries); i++) {
                        debugfs_create_file(hdmi_debugfs_entries[i].name,

--
Hamza