Re: [PATCH] drm/i915/vlv: T12 eDP panel timing enforcement during reboot

[Clint Taylor <clinton.a.taylor@intel.com>]

On 07/02/2014 01:35 AM, Jani Nikula wrote:
> From: Clint Taylor <Clinton.A.Taylor@intel.com>
>
> The panel power sequencer on vlv doesn't appear to accept changes to its
> T12 power down duration during warm reboots. This change forces a delay
> for warm reboots to the T12 panel timing as defined in the VBT table for
> the connected panel.
>
> Ver2: removed redundant pr_crit(), commented magic value for pp_div_reg
>
> Ver3: moved SYS_RESTART check earlier, new name for pp_div.
>
> Ver4: Minor issue changes
>
> Signed-off-by: Clint Taylor <clinton.a.taylor@intel.com>
> [Jani: rebased on current -nightly.]
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>
> ---
>
> I ended up doing the rebase myself, but I'd like to have a quick review
> before pushing.

Quick review complete. Everything appears OK.


>
> Thanks,
> Jani.
> ---
>   drivers/gpu/drm/i915/intel_dp.c  | 40 ++++++++++++++++++++++++++++++++++++++++
>   drivers/gpu/drm/i915/intel_drv.h |  2 ++
>   2 files changed, 42 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index b5ec48913b47..f0d23c435cf6 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -28,6 +28,8 @@
>   #include <linux/i2c.h>
>   #include <linux/slab.h>
>   #include <linux/export.h>
> +#include <linux/notifier.h>
> +#include <linux/reboot.h>
>   #include <drm/drmP.h>
>   #include <drm/drm_crtc.h>
>   #include <drm/drm_crtc_helper.h>
> @@ -336,6 +338,36 @@ static u32 _pp_stat_reg(struct intel_dp *intel_dp)
>   		return VLV_PIPE_PP_STATUS(vlv_power_sequencer_pipe(intel_dp));
>   }
>
> +/* Reboot notifier handler to shutdown panel power to guarantee T12 timing */
> +static int edp_notify_handler(struct notifier_block *this, unsigned long code,
> +			      void *unused)
> +{
> +	struct intel_dp *intel_dp = container_of(this, typeof(* intel_dp),
> +						 edp_notifier);
> +	struct drm_device *dev = intel_dp_to_dev(intel_dp);
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	u32 pp_div;
> +	u32 pp_ctrl_reg, pp_div_reg;
> +	enum pipe pipe = vlv_power_sequencer_pipe(intel_dp);
> +
> +	if (!is_edp(intel_dp) || code != SYS_RESTART)
> +		return 0;
> +
> +	if (IS_VALLEYVIEW(dev)) {
> +		pp_ctrl_reg = VLV_PIPE_PP_CONTROL(pipe);
> +		pp_div_reg  = VLV_PIPE_PP_DIVISOR(pipe);
> +		pp_div = I915_READ(VLV_PIPE_PP_DIVISOR(pipe));
> +		pp_div &= PP_REFERENCE_DIVIDER_MASK;
> +
> +		/* 0x1F write to PP_DIV_REG sets max cycle delay */
> +		I915_WRITE(pp_div_reg, pp_div | 0x1F);
> +		I915_WRITE(pp_ctrl_reg, PANEL_UNLOCK_REGS | PANEL_POWER_OFF);
> +		msleep(intel_dp->panel_power_cycle_delay);
> +	}
> +
> +	return 0;
> +}
> +
>   static bool edp_have_panel_power(struct intel_dp *intel_dp)
>   {
>   	struct drm_device *dev = intel_dp_to_dev(intel_dp);
> @@ -3785,6 +3817,10 @@ void intel_dp_encoder_destroy(struct drm_encoder *encoder)
>   		drm_modeset_lock(&dev->mode_config.connection_mutex, NULL);
>   		edp_panel_vdd_off_sync(intel_dp);
>   		drm_modeset_unlock(&dev->mode_config.connection_mutex);
> +		if (intel_dp->edp_notifier.notifier_call) {
> +			unregister_reboot_notifier(&intel_dp->edp_notifier);
> +			intel_dp->edp_notifier.notifier_call = NULL;
> +		}
>   	}
>   	kfree(intel_dig_port);
>   }
> @@ -4353,6 +4389,10 @@ intel_dp_init_connector(struct intel_digital_port *intel_dig_port,
>   	if (is_edp(intel_dp)) {
>   		intel_dp_init_panel_power_timestamps(intel_dp);
>   		intel_dp_init_panel_power_sequencer(dev, intel_dp, &power_seq);
> +		if (IS_VALLEYVIEW(dev)) {
> +			intel_dp->edp_notifier.notifier_call = edp_notify_handler;
> +			register_reboot_notifier(&intel_dp->edp_notifier);
> +		}
>   	}
>
>   	intel_dp_aux_init(intel_dp, intel_connector);
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 5f7c7bd94d90..87d1715db21d 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -541,6 +541,8 @@ struct intel_dp {
>   	unsigned long last_power_cycle;
>   	unsigned long last_power_on;
>   	unsigned long last_backlight_off;
> +	struct notifier_block edp_notifier;
> +
>   	bool use_tps3;
>   	struct intel_connector *attached_connector;
>
>