On Wed, 30 Mar 2016, Yetunde Adebisi <yetundex.adebisi@xxxxxxxxx> wrote:
> This patch enables support for DPCD backlight control for DP connectors.
> The VESA spec defines DPCD backlight control only for eDP but some add-on
> cards like the Chrontel CH7511B DP-LVDS cards have the display control
> DPCD registers enabled.
> This patch registers a backlight device exposed via sysfs that controls the
> connected panel backlight by writing to DPCD registers on the CH7511B
> add-on card
I'm not convinced. Seems like a gross spec violating hack to work around
the issue that CH7511B is not configured as eDP in the first place.
BR,
Jani.
>
> Signed-off-by: Yetunde Adebisi <yetundex.adebisi@xxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_dp.c | 25 ++++++++++++++++++++
> drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 7 ++++++
> drivers/gpu/drm/i915/intel_drv.h | 2 ++
> drivers/gpu/drm/i915/intel_panel.c | 33 +++++++++++++++++++--------
> 4 files changed, 57 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 9e9e7f1..8bbfb7f 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -5631,6 +5631,30 @@ intel_dp_drrs_init(struct intel_connector *intel_connector,
> return downclock_mode;
> }
>
> +/*
> + * Called on DP connector initialization to check for aux backlight control
> + * capability on the sink device and if present, initialize it.
> + */
> +static void intel_dp_init_aux_backlight(struct intel_dp *intel_dp,
> + struct drm_connector *connector)
> +{
> + struct intel_connector *intel_connector = to_intel_connector(connector);
> +
> + if (is_edp(intel_dp))
> + return;
> +
> + if (i915.enable_dpcd_backlight &&
> + (intel_dp_dpcd_read_wake(&intel_dp->aux, DP_EDP_DPCD_REV,
> + intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd)) ==
> + sizeof(intel_dp->edp_dpcd)) &&
> + intel_dp_aux_init_backlight_funcs(intel_connector) == 0) {
> + intel_panel_setup_backlight(connector, INVALID_PIPE);
> +
> + intel_connector->panel.backlight.power = intel_dp_aux_backlight_power;
> + intel_connector->panel.backlight.enabled = true;
> + }
> +}
> +
> static bool intel_edp_init_connector(struct intel_dp *intel_dp,
> struct intel_connector *intel_connector)
> {
> @@ -5868,6 +5892,7 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
> goto fail;
> }
>
> + intel_dp_init_aux_backlight(intel_dp, connector);
> intel_dp_add_properties(intel_dp, connector);
>
> /* For G4X desktop chip, PEG_BAND_GAP_DATA 3:0 must first be written
> diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> index a5361d6..efa657f 100644
> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -168,3 +168,10 @@ int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector)
>
> return 0;
> }
> +
> +void intel_dp_aux_backlight_power(struct intel_connector *connector,
> + bool enable)
> +{
> + set_aux_backlight_enable(enc_to_intel_dp(&connector->encoder->base),
> + enable);
> +}
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 782a103..ab92e89 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -1324,6 +1324,8 @@ ssize_t intel_dp_dpcd_read_wake(struct drm_dp_aux *aux, unsigned int offset,
>
> /* intel_dp_aux_backlight.c */
> int intel_dp_aux_init_backlight_funcs(struct intel_connector *intel_connector);
> +void intel_dp_aux_backlight_power(struct intel_connector *connector,
> + bool enable);
>
> /* intel_dp_mst.c */
> int intel_dp_mst_encoder_init(struct intel_digital_port *intel_dig_port, int conn_id);
> diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> index cdfcdad..d678e55 100644
> --- a/drivers/gpu/drm/i915/intel_panel.c
> +++ b/drivers/gpu/drm/i915/intel_panel.c
> @@ -1193,16 +1193,29 @@ static int intel_backlight_device_register(struct intel_connector *connector)
> else
> props.power = FB_BLANK_POWERDOWN;
>
> - /*
> - * Note: using the same name independent of the connector prevents
> - * registration of multiple backlight devices in the driver.
> - */
> - panel->backlight.device =
> - backlight_device_register("intel_backlight",
> - connector->base.kdev,
> - connector,
> - &intel_backlight_device_ops, &props);
> -
> + if (connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
> + char *name = kasprintf(GFP_KERNEL, "intel_aux_backlight-%s",
> + connector->base.name);
> + if (!name)
> + return -ENOMEM;
> +
> + panel->backlight.device =
> + backlight_device_register(name,
> + connector->base.kdev,
> + connector,
> + &intel_backlight_device_ops, &props);
> + kfree(name);
> + } else {
> + /*
> + * Note: using the same name independent of the connector prevents
> + * registration of multiple backlight devices in the driver.
> + */
> + panel->backlight.device =
> + backlight_device_register("intel_backlight",
> + connector->base.kdev,
> + connector,
> + &intel_backlight_device_ops, &props);
> + }
> if (IS_ERR(panel->backlight.device)) {
> DRM_ERROR("Failed to register backlight: %ld\n",
> PTR_ERR(panel->backlight.device));
--
Jani Nikula, Intel Open Source Technology Center
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