linux-zen-desktop/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c

550 lines
21 KiB
C

/*
* Copyright © 2015 Intel Corporation
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice (including the next
* paragraph) shall be included in all copies or substantial portions of the
* Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
*/
/*
* Laptops with Intel GPUs which have panels that support controlling the
* backlight through DP AUX can actually use two different interfaces: Intel's
* proprietary DP AUX backlight interface, and the standard VESA backlight
* interface. Unfortunately, at the time of writing this a lot of laptops will
* advertise support for the standard VESA backlight interface when they
* don't properly support it. However, on these systems the Intel backlight
* interface generally does work properly. Additionally, these systems will
* usually just indicate that they use PWM backlight controls in their VBIOS
* for some reason.
*/
#include "i915_drv.h"
#include "intel_backlight.h"
#include "intel_display_types.h"
#include "intel_dp.h"
#include "intel_dp_aux_backlight.h"
/* TODO:
* Implement HDR, right now we just implement the bare minimum to bring us back into SDR mode so we
* can make people's backlights work in the mean time
*/
/*
* DP AUX registers for Intel's proprietary HDR backlight interface. We define
* them here since we'll likely be the only driver to ever use these.
*/
#define INTEL_EDP_HDR_TCON_CAP0 0x340
#define INTEL_EDP_HDR_TCON_CAP1 0x341
# define INTEL_EDP_HDR_TCON_2084_DECODE_CAP BIT(0)
# define INTEL_EDP_HDR_TCON_2020_GAMUT_CAP BIT(1)
# define INTEL_EDP_HDR_TCON_TONE_MAPPING_CAP BIT(2)
# define INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_CAP BIT(3)
# define INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP BIT(4)
# define INTEL_EDP_HDR_TCON_OPTIMIZATION_CAP BIT(5)
# define INTEL_EDP_HDR_TCON_SDP_COLORIMETRY_CAP BIT(6)
# define INTEL_EDP_HDR_TCON_SRGB_TO_PANEL_GAMUT_CONVERSION_CAP BIT(7)
#define INTEL_EDP_HDR_TCON_CAP2 0x342
# define INTEL_EDP_SDR_TCON_BRIGHTNESS_AUX_CAP BIT(0)
#define INTEL_EDP_HDR_TCON_CAP3 0x343
#define INTEL_EDP_HDR_GETSET_CTRL_PARAMS 0x344
# define INTEL_EDP_HDR_TCON_2084_DECODE_ENABLE BIT(0)
# define INTEL_EDP_HDR_TCON_2020_GAMUT_ENABLE BIT(1)
# define INTEL_EDP_HDR_TCON_TONE_MAPPING_ENABLE BIT(2) /* Pre-TGL+ */
# define INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_ENABLE BIT(3)
# define INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE BIT(4)
# define INTEL_EDP_HDR_TCON_SRGB_TO_PANEL_GAMUT_ENABLE BIT(5)
/* Bit 6 is reserved */
# define INTEL_EDP_HDR_TCON_SDP_COLORIMETRY_ENABLE BIT(7)
#define INTEL_EDP_HDR_CONTENT_LUMINANCE 0x346 /* Pre-TGL+ */
#define INTEL_EDP_HDR_PANEL_LUMINANCE_OVERRIDE 0x34A
#define INTEL_EDP_SDR_LUMINANCE_LEVEL 0x352
#define INTEL_EDP_BRIGHTNESS_NITS_LSB 0x354
#define INTEL_EDP_BRIGHTNESS_NITS_MSB 0x355
#define INTEL_EDP_BRIGHTNESS_DELAY_FRAMES 0x356
#define INTEL_EDP_BRIGHTNESS_PER_FRAME_STEPS 0x357
#define INTEL_EDP_BRIGHTNESS_OPTIMIZATION_0 0x358
# define INTEL_EDP_TCON_USAGE_MASK GENMASK(0, 3)
# define INTEL_EDP_TCON_USAGE_UNKNOWN 0x0
# define INTEL_EDP_TCON_USAGE_DESKTOP 0x1
# define INTEL_EDP_TCON_USAGE_FULL_SCREEN_MEDIA 0x2
# define INTEL_EDP_TCON_USAGE_FULL_SCREEN_GAMING 0x3
# define INTEL_EDP_TCON_POWER_MASK BIT(4)
# define INTEL_EDP_TCON_POWER_DC (0 << 4)
# define INTEL_EDP_TCON_POWER_AC (1 << 4)
# define INTEL_EDP_TCON_OPTIMIZATION_STRENGTH_MASK GENMASK(5, 7)
#define INTEL_EDP_BRIGHTNESS_OPTIMIZATION_1 0x359
enum intel_dp_aux_backlight_modparam {
INTEL_DP_AUX_BACKLIGHT_AUTO = -1,
INTEL_DP_AUX_BACKLIGHT_OFF = 0,
INTEL_DP_AUX_BACKLIGHT_ON = 1,
INTEL_DP_AUX_BACKLIGHT_FORCE_VESA = 2,
INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL = 3,
};
static bool is_intel_tcon_cap(const u8 tcon_cap[4])
{
return tcon_cap[0] >= 1;
}
/* Intel EDP backlight callbacks */
static bool
intel_dp_aux_supports_hdr_backlight(struct intel_connector *connector)
{
struct drm_i915_private *i915 = to_i915(connector->base.dev);
struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
struct drm_dp_aux *aux = &intel_dp->aux;
struct intel_panel *panel = &connector->panel;
int ret;
u8 tcon_cap[4];
intel_dp_wait_source_oui(intel_dp);
ret = drm_dp_dpcd_read(aux, INTEL_EDP_HDR_TCON_CAP0, tcon_cap, sizeof(tcon_cap));
if (ret != sizeof(tcon_cap))
return false;
if (!(tcon_cap[1] & INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP))
return false;
drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Detected %s HDR backlight interface version %d\n",
connector->base.base.id, connector->base.name,
is_intel_tcon_cap(tcon_cap) ? "Intel" : "unsupported", tcon_cap[0]);
if (!is_intel_tcon_cap(tcon_cap))
return false;
/*
* If we don't have HDR static metadata there is no way to
* runtime detect used range for nits based control. For now
* do not use Intel proprietary eDP backlight control if we
* don't have this data in panel EDID. In case we find panel
* which supports only nits based control, but doesn't provide
* HDR static metadata we need to start maintaining table of
* ranges for such panels.
*/
if (i915->params.enable_dpcd_backlight != INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL &&
!(connector->base.hdr_sink_metadata.hdmi_type1.metadata_type &
BIT(HDMI_STATIC_METADATA_TYPE1))) {
drm_info(&i915->drm,
"[CONNECTOR:%d:%s] Panel is missing HDR static metadata. Possible support for Intel HDR backlight interface is not used. If your backlight controls don't work try booting with i915.enable_dpcd_backlight=%d. needs this, please file a _new_ bug report on drm/i915, see " FDO_BUG_URL " for details.\n",
connector->base.base.id, connector->base.name,
INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL);
return false;
}
panel->backlight.edp.intel.sdr_uses_aux =
tcon_cap[2] & INTEL_EDP_SDR_TCON_BRIGHTNESS_AUX_CAP;
return true;
}
static u32
intel_dp_aux_hdr_get_backlight(struct intel_connector *connector, enum pipe pipe)
{
struct drm_i915_private *i915 = to_i915(connector->base.dev);
struct intel_panel *panel = &connector->panel;
struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
u8 tmp;
u8 buf[2] = { 0 };
if (drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &tmp) != 1) {
drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to read current backlight mode from DPCD\n",
connector->base.base.id, connector->base.name);
return 0;
}
if (!(tmp & INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE)) {
if (!panel->backlight.edp.intel.sdr_uses_aux) {
u32 pwm_level = panel->backlight.pwm_funcs->get(connector, pipe);
return intel_backlight_level_from_pwm(connector, pwm_level);
}
/* Assume 100% brightness if backlight controls aren't enabled yet */
return panel->backlight.max;
}
if (drm_dp_dpcd_read(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
sizeof(buf)) != sizeof(buf)) {
drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to read brightness from DPCD\n",
connector->base.base.id, connector->base.name);
return 0;
}
return (buf[1] << 8 | buf[0]);
}
static void
intel_dp_aux_hdr_set_aux_backlight(const struct drm_connector_state *conn_state, u32 level)
{
struct intel_connector *connector = to_intel_connector(conn_state->connector);
struct drm_device *dev = connector->base.dev;
struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
u8 buf[4] = { 0 };
buf[0] = level & 0xFF;
buf[1] = (level & 0xFF00) >> 8;
if (drm_dp_dpcd_write(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
sizeof(buf)) != sizeof(buf))
drm_err(dev, "[CONNECTOR:%d:%s] Failed to write brightness level to DPCD\n",
connector->base.base.id, connector->base.name);
}
static void
intel_dp_aux_hdr_set_backlight(const struct drm_connector_state *conn_state, u32 level)
{
struct intel_connector *connector = to_intel_connector(conn_state->connector);
struct intel_panel *panel = &connector->panel;
if (panel->backlight.edp.intel.sdr_uses_aux) {
intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
} else {
const u32 pwm_level = intel_backlight_level_to_pwm(connector, level);
intel_backlight_set_pwm_level(conn_state, pwm_level);
}
}
static void
intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
const struct drm_connector_state *conn_state, u32 level)
{
struct intel_connector *connector = to_intel_connector(conn_state->connector);
struct intel_panel *panel = &connector->panel;
struct drm_i915_private *i915 = to_i915(connector->base.dev);
struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
int ret;
u8 old_ctrl, ctrl;
intel_dp_wait_source_oui(intel_dp);
ret = drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &old_ctrl);
if (ret != 1) {
drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to read current backlight control mode: %d\n",
connector->base.base.id, connector->base.name, ret);
return;
}
ctrl = old_ctrl;
if (panel->backlight.edp.intel.sdr_uses_aux) {
ctrl |= INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
} else {
u32 pwm_level = intel_backlight_level_to_pwm(connector, level);
panel->backlight.pwm_funcs->enable(crtc_state, conn_state, pwm_level);
ctrl &= ~INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
}
if (ctrl != old_ctrl &&
drm_dp_dpcd_writeb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, ctrl) != 1)
drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to configure DPCD brightness controls\n",
connector->base.base.id, connector->base.name);
}
static void
intel_dp_aux_hdr_disable_backlight(const struct drm_connector_state *conn_state, u32 level)
{
struct intel_connector *connector = to_intel_connector(conn_state->connector);
struct intel_panel *panel = &connector->panel;
/* Nothing to do for AUX based backlight controls */
if (panel->backlight.edp.intel.sdr_uses_aux)
return;
/* Note we want the actual pwm_level to be 0, regardless of pwm_min */
panel->backlight.pwm_funcs->disable(conn_state, intel_backlight_invert_pwm_level(connector, 0));
}
static const char *dpcd_vs_pwm_str(bool aux)
{
return aux ? "DPCD" : "PWM";
}
static int
intel_dp_aux_hdr_setup_backlight(struct intel_connector *connector, enum pipe pipe)
{
struct drm_i915_private *i915 = to_i915(connector->base.dev);
struct intel_panel *panel = &connector->panel;
struct drm_luminance_range_info *luminance_range =
&connector->base.display_info.luminance_range;
int ret;
drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] SDR backlight is controlled through %s\n",
connector->base.base.id, connector->base.name,
dpcd_vs_pwm_str(panel->backlight.edp.intel.sdr_uses_aux));
if (!panel->backlight.edp.intel.sdr_uses_aux) {
ret = panel->backlight.pwm_funcs->setup(connector, pipe);
if (ret < 0) {
drm_err(&i915->drm,
"[CONNECTOR:%d:%s] Failed to setup SDR backlight controls through PWM: %d\n",
connector->base.base.id, connector->base.name, ret);
return ret;
}
}
if (luminance_range->max_luminance) {
panel->backlight.max = luminance_range->max_luminance;
panel->backlight.min = luminance_range->min_luminance;
} else {
panel->backlight.max = 512;
panel->backlight.min = 0;
}
drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Using AUX HDR interface for backlight control (range %d..%d)\n",
connector->base.base.id, connector->base.name,
panel->backlight.min, panel->backlight.max);
panel->backlight.level = intel_dp_aux_hdr_get_backlight(connector, pipe);
panel->backlight.enabled = panel->backlight.level != 0;
return 0;
}
/* VESA backlight callbacks */
static u32 intel_dp_aux_vesa_get_backlight(struct intel_connector *connector, enum pipe unused)
{
return connector->panel.backlight.level;
}
static void
intel_dp_aux_vesa_set_backlight(const struct drm_connector_state *conn_state, u32 level)
{
struct intel_connector *connector = to_intel_connector(conn_state->connector);
struct intel_panel *panel = &connector->panel;
struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
if (!panel->backlight.edp.vesa.info.aux_set) {
const u32 pwm_level = intel_backlight_level_to_pwm(connector, level);
intel_backlight_set_pwm_level(conn_state, pwm_level);
}
drm_edp_backlight_set_level(&intel_dp->aux, &panel->backlight.edp.vesa.info, level);
}
static void
intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
const struct drm_connector_state *conn_state, u32 level)
{
struct intel_connector *connector = to_intel_connector(conn_state->connector);
struct intel_panel *panel = &connector->panel;
struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
if (!panel->backlight.edp.vesa.info.aux_enable) {
u32 pwm_level;
if (!panel->backlight.edp.vesa.info.aux_set)
pwm_level = intel_backlight_level_to_pwm(connector, level);
else
pwm_level = intel_backlight_invert_pwm_level(connector,
panel->backlight.pwm_level_max);
panel->backlight.pwm_funcs->enable(crtc_state, conn_state, pwm_level);
}
drm_edp_backlight_enable(&intel_dp->aux, &panel->backlight.edp.vesa.info, level);
}
static void intel_dp_aux_vesa_disable_backlight(const struct drm_connector_state *old_conn_state,
u32 level)
{
struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
struct intel_panel *panel = &connector->panel;
struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
drm_edp_backlight_disable(&intel_dp->aux, &panel->backlight.edp.vesa.info);
if (!panel->backlight.edp.vesa.info.aux_enable)
panel->backlight.pwm_funcs->disable(old_conn_state,
intel_backlight_invert_pwm_level(connector, 0));
}
static int intel_dp_aux_vesa_setup_backlight(struct intel_connector *connector, enum pipe pipe)
{
struct intel_dp *intel_dp = intel_attached_dp(connector);
struct intel_panel *panel = &connector->panel;
struct drm_i915_private *i915 = dp_to_i915(intel_dp);
u16 current_level;
u8 current_mode;
int ret;
ret = drm_edp_backlight_init(&intel_dp->aux, &panel->backlight.edp.vesa.info,
panel->vbt.backlight.pwm_freq_hz, intel_dp->edp_dpcd,
&current_level, &current_mode);
if (ret < 0)
return ret;
drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] AUX VESA backlight enable is controlled through %s\n",
connector->base.base.id, connector->base.name,
dpcd_vs_pwm_str(panel->backlight.edp.vesa.info.aux_enable));
drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] AUX VESA backlight level is controlled through %s\n",
connector->base.base.id, connector->base.name,
dpcd_vs_pwm_str(panel->backlight.edp.vesa.info.aux_set));
if (!panel->backlight.edp.vesa.info.aux_set || !panel->backlight.edp.vesa.info.aux_enable) {
ret = panel->backlight.pwm_funcs->setup(connector, pipe);
if (ret < 0) {
drm_err(&i915->drm,
"[CONNECTOR:%d:%s] Failed to setup PWM backlight controls for eDP backlight: %d\n",
connector->base.base.id, connector->base.name, ret);
return ret;
}
}
if (panel->backlight.edp.vesa.info.aux_set) {
panel->backlight.max = panel->backlight.edp.vesa.info.max;
panel->backlight.min = 0;
if (current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {
panel->backlight.level = current_level;
panel->backlight.enabled = panel->backlight.level != 0;
} else {
panel->backlight.level = panel->backlight.max;
panel->backlight.enabled = false;
}
} else {
panel->backlight.max = panel->backlight.pwm_level_max;
panel->backlight.min = panel->backlight.pwm_level_min;
if (current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_PWM) {
panel->backlight.level = panel->backlight.pwm_funcs->get(connector, pipe);
panel->backlight.enabled = panel->backlight.pwm_enabled;
} else {
panel->backlight.level = panel->backlight.max;
panel->backlight.enabled = false;
}
}
drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Using AUX VESA interface for backlight control\n",
connector->base.base.id, connector->base.name);
return 0;
}
static bool
intel_dp_aux_supports_vesa_backlight(struct intel_connector *connector)
{
struct intel_dp *intel_dp = intel_attached_dp(connector);
struct drm_i915_private *i915 = dp_to_i915(intel_dp);
if (drm_edp_backlight_supported(intel_dp->edp_dpcd)) {
drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] AUX Backlight Control Supported!\n",
connector->base.base.id, connector->base.name);
return true;
}
return false;
}
static const struct intel_panel_bl_funcs intel_dp_hdr_bl_funcs = {
.setup = intel_dp_aux_hdr_setup_backlight,
.enable = intel_dp_aux_hdr_enable_backlight,
.disable = intel_dp_aux_hdr_disable_backlight,
.set = intel_dp_aux_hdr_set_backlight,
.get = intel_dp_aux_hdr_get_backlight,
};
static const struct intel_panel_bl_funcs intel_dp_vesa_bl_funcs = {
.setup = intel_dp_aux_vesa_setup_backlight,
.enable = intel_dp_aux_vesa_enable_backlight,
.disable = intel_dp_aux_vesa_disable_backlight,
.set = intel_dp_aux_vesa_set_backlight,
.get = intel_dp_aux_vesa_get_backlight,
};
int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
{
struct drm_device *dev = connector->base.dev;
struct intel_panel *panel = &connector->panel;
struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
struct drm_i915_private *i915 = dp_to_i915(intel_dp);
bool try_intel_interface = false, try_vesa_interface = false;
/* Check the VBT and user's module parameters to figure out which
* interfaces to probe
*/
switch (i915->params.enable_dpcd_backlight) {
case INTEL_DP_AUX_BACKLIGHT_OFF:
return -ENODEV;
case INTEL_DP_AUX_BACKLIGHT_AUTO:
switch (panel->vbt.backlight.type) {
case INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE:
try_vesa_interface = true;
break;
case INTEL_BACKLIGHT_DISPLAY_DDI:
try_intel_interface = true;
break;
default:
return -ENODEV;
}
break;
case INTEL_DP_AUX_BACKLIGHT_ON:
if (panel->vbt.backlight.type != INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE)
try_intel_interface = true;
try_vesa_interface = true;
break;
case INTEL_DP_AUX_BACKLIGHT_FORCE_VESA:
try_vesa_interface = true;
break;
case INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL:
try_intel_interface = true;
break;
}
/*
* Since Intel has their own backlight control interface, the majority of machines out there
* using DPCD backlight controls with Intel GPUs will be using this interface as opposed to
* the VESA interface. However, other GPUs (such as Nvidia's) will always use the VESA
* interface. This means that there's quite a number of panels out there that will advertise
* support for both interfaces, primarily systems with Intel/Nvidia hybrid GPU setups.
*
* There's a catch to this though: on many panels that advertise support for both
* interfaces, the VESA backlight interface will stop working once we've programmed the
* panel with Intel's OUI - which is also required for us to be able to detect Intel's
* backlight interface at all. This means that the only sensible way for us to detect both
* interfaces is to probe for Intel's first, and VESA's second.
*/
if (try_intel_interface && intel_dp_aux_supports_hdr_backlight(connector)) {
drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using Intel proprietary eDP backlight controls\n",
connector->base.base.id, connector->base.name);
panel->backlight.funcs = &intel_dp_hdr_bl_funcs;
return 0;
}
if (try_vesa_interface && intel_dp_aux_supports_vesa_backlight(connector)) {
drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using VESA eDP backlight controls\n",
connector->base.base.id, connector->base.name);
panel->backlight.funcs = &intel_dp_vesa_bl_funcs;
return 0;
}
return -ENODEV;
}