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

Daniel Vetter
2016-05-08T16:24:09Z

On Tue, Apr 26, 2016 at 12:25:18PM +0100, Yetunde Adebisi wrote:
> 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>

Just a quick comment since I'm typing the regular changelog summaries: I
think the backlight driver in here would have been real nice as a generic
thing on top of the dp aux library. But ok if the next person gets to do
that, too ;-)
-Daniel

> ---
> 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;
> --
> 1.9.3
>
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--
Daniel Vetter
Software Engineer, Intel Corporation