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

[Hamza Mahfooz <hamza.mahfooz@xxxxxxx>]

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.limonciello@xxxxxxx>

Reviewed-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>

> ---
>   .../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