[PATCH 3/3] drm/i915: Add Backlight Control using DPCD for eDP connectors (v9)

Yetunde Adebisi
2016-04-26T11:25:29Z

This patch adds support for eDP backlight control using DPCD registers to
backlight hooks in intel_panel.

It checks for backlight control over AUX channel capability and sets up
function pointers to get and set the backlight brightness level if
supported.

v2: Moved backlight functions from intel_dp.c into a new file
intel_dp_aux_backlight.c. Also moved reading of eDP display control
registers to intel_dp_get_dpcd

v3: Correct some formatting mistakes

v4: Updated to use AUX backlight control if PWM control is not possible
(Jani)
v5: Moved call to initialize backlight registers to dp_aux_setup_backlight
v6: Check DP_EDP_BACKLIGHT_PIN_ENABLE_CAP is disabled before setting up AUX
backlight control. To fix BLM_PWM_ENABLE igt test warnings on bdw_ultra
v7: Add enable_dpcd_backlight module parameter.
v8: Rebase onto latest drm-intel-nightly branch
v9: Remove references to intel_dp_dpcd_read_wake
Split addition edp_dpcd variable into a separate patch

Cc: Bob Paauwe <bob.j.paauwe@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Yetunde Adebisi <yetundex.adebisi@intel.com>
---
drivers/gpu/drm/i915/Makefile | 1 +
drivers/gpu/drm/i915/i915_params.c | 4 +
drivers/gpu/drm/i915/i915_params.h | 1 +
drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 173 ++++++++++++++++++++++++++
drivers/gpu/drm/i915/intel_drv.h | 3 +
drivers/gpu/drm/i915/intel_panel.c | 4 +
6 files changed, 186 insertions(+)
create mode 100644 drivers/gpu/drm/i915/intel_dp_aux_backlight.c

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 0b88ba0..723c502 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -81,6 +81,7 @@ i915-y += dvo_ch7017.o \
dvo_tfp410.o \
intel_crt.o \
intel_ddi.o \
+ intel_dp_aux_backlight.o \
intel_dp_link_training.o \
intel_dp_mst.o \
intel_dp.o \
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 1779f02..383c076 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -58,6 +58,7 @@ struct i915_params i915 __read_mostly = {
.guc_log_level = -1,
.enable_dp_mst = true,
.inject_load_failure = 0,
+ .enable_dpcd_backlight = false,
};

module_param_named(modeset, i915.modeset, int, 0400);
@@ -210,3 +211,6 @@ MODULE_PARM_DESC(enable_dp_mst,
module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
MODULE_PARM_DESC(inject_load_failure,
"Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");
+module_param_named(enable_dpcd_backlight, i915.enable_dpcd_backlight, bool, 0600);
+MODULE_PARM_DESC(enable_dpcd_backlight,
+ "Enable support for DPCD backlight control (default:false)");
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 02bc278..65e73dd 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -61,6 +61,7 @@ struct i915_params {
bool verbose_state_checks;
bool nuclear_pageflip;
bool enable_dp_mst;
+ bool enable_dpcd_backlight;
};

extern struct i915_params i915 __read_mostly;
diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
new file mode 100644
index 0000000..984fb0d
--- /dev/null
+++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
@@ -0,0 +1,173 @@
+/*
+ * 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.
+ *
+ */
+
+#include "intel_drv.h"
+
+static void set_aux_backlight_enable(struct intel_dp *intel_dp, bool enable)
+{
+ uint8_t reg_val = 0;
+
+ if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
+ &reg_val) < 0) {
+ DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
+ DP_EDP_DISPLAY_CONTROL_REGISTER);
+ return;
+ }
+ if (enable)
+ reg_val |= DP_EDP_BACKLIGHT_ENABLE;
+ else
+ reg_val &= ~(DP_EDP_BACKLIGHT_ENABLE);
+
+ if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
+ reg_val) != 1) {
+ DRM_DEBUG_KMS("Failed to %s aux backlight\n",
+ enable ? "enable" : "disable");
+ }
+}
+
+/*
+ * Read the current backlight value from DPCD register(s) based
+ * on if 8-bit(MSB) or 16-bit(MSB and LSB) values are supported
+ */
+static uint32_t intel_dp_aux_get_backlight(struct intel_connector *connector)
+{
+ struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+ uint8_t read_val[2] = { 0x0 };
+ uint16_t level = 0;
+
+ if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
+ &read_val, sizeof(read_val)) < 0) {
+ DRM_DEBUG_KMS("Failed to read DPCD register 0x%x\n",
+ DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
+ return 0;
+ }
+ level = read_val[0];
+ if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
+ level = (read_val[0] << 8 | read_val[1]);
+
+ return level;
+}
+
+/*
+ * Sends the current backlight level over the aux channel, checking if its using
+ * 8-bit or 16 bit value (MSB and LSB)
+ */
+static void
+intel_dp_aux_set_backlight(struct intel_connector *connector, u32 level)
+{
+ struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+ uint8_t vals[2] = { 0x0 };
+
+ vals[0] = level;
+
+ /* Write the MSB and/or LSB */
+ if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT) {
+ vals[0] = (level & 0xFF00) >> 8;
+ vals[1] = (level & 0xFF);
+ }
+ if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
+ vals, sizeof(vals)) < 0) {
+ DRM_DEBUG_KMS("Failed to write aux backlight level\n");
+ return;
+ }
+}
+
+static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
+{
+ struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+ uint8_t dpcd_buf = 0;
+
+ set_aux_backlight_enable(intel_dp, true);
+
+ if ((drm_dp_dpcd_readb(&intel_dp->aux,
+ DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) == 1) &&
+ ((dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK) ==
+ DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET))
+ drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
+ (dpcd_buf | DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD));
+}
+
+static void intel_dp_aux_disable_backlight(struct intel_connector *connector)
+{
+ set_aux_backlight_enable(enc_to_intel_dp(&connector->encoder->base), false);
+}
+
+static int intel_dp_aux_setup_backlight(struct intel_connector *connector,
+ enum pipe pipe)
+{
+ struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+ struct intel_panel *panel = &connector->panel;
+
+ intel_dp_aux_enable_backlight(connector);
+
+ if (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_BYTE_COUNT)
+ panel->backlight.max = 0xFFFF;
+ else
+ panel->backlight.max = 0xFF;
+
+ panel->backlight.min = 0;
+ panel->backlight.level = intel_dp_aux_get_backlight(connector);
+
+ panel->backlight.enabled = panel->backlight.level != 0;
+
+ return 0;
+}
+
+static bool
+intel_dp_aux_display_control_capable(struct intel_connector *connector)
+{
+ struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
+
+ /* Check the eDP Display control capabilities registers to determine if
+ * the panel can support backlight control over the aux channel
+ */
+ if (intel_dp->edp_dpcd[1] & DP_EDP_TCON_BACKLIGHT_ADJUSTMENT_CAP &&
+ (intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP) &&
+ !((intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_PIN_ENABLE_CAP) ||
+ (intel_dp->edp_dpcd[2] & DP_EDP_BACKLIGHT_BRIGHTNESS_PWM_PIN_CAP))) {
+
+ DRM_DEBUG_KMS("AUX Backlight Control Supported!\n");
+ return true;
+ }
+ return false;
+}
+
+int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
+{
+ struct intel_panel *panel = &intel_connector->panel;
+
+ if(!i915.enable_dpcd_backlight)
+ return -ENODEV;
+
+ if (!intel_dp_aux_display_control_capable(intel_connector))
+ return -ENODEV;
+
+ panel->backlight.setup = intel_dp_aux_setup_backlight;
+ panel->backlight.enable = intel_dp_aux_enable_backlight;
+ panel->backlight.disable = intel_dp_aux_disable_backlight;
+ panel->backlight.set = intel_dp_aux_set_backlight;
+ panel->backlight.get = intel_dp_aux_get_backlight;
+
+ return 0;
+}
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 99db8bb..cb89a35 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -1337,6 +1337,9 @@ bool intel_dp_source_supports_hbr2(struct intel_dp *intel_dp);
bool
intel_dp_get_link_status(struct intel_dp *intel_dp, uint8_t link_status[DP_LINK_STATUS_SIZE]);

+/* intel_dp_aux_backlight.c */
+int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector);
+
/* intel_dp_mst.c */
int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
void intel_dp_mst_encoder_cleanup(struct intel_digital_port *intel_dig_port);
diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
index a078876..bd31481 100644
--- a/drivers/gpu/drm/i915/intel_panel.c
+++ b/drivers/gpu/drm/i915/intel_panel.c
@@ -1718,6 +1718,10 @@ intel_panel_init_backlight_funcs(struct intel_panel *panel)
container_of(panel, struct intel_connector, panel);
struct drm_i915_private *dev_priv = to_i915(connector->base.dev);

+ if (connector->base.connector_type == DRM_MODE_CONNECTOR_eDP &&
+ intel_dp_aux_init_backlight_funcs(connector) == 0)
+ return;
+
if (IS_BROXTON(dev_priv)) {
panel->backlight.setup = bxt_setup_backlight;
panel->backlight.enable = bxt_enable_backlight;