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

[Jani Nikula <jani.nikula@linux.intel.com>]

On Sat, 17 May 2014, clinton.a.taylor@intel.com 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.

Wrap to about 72 cols.

>
> Ver2: removed redundant pr_crit(), commented magic value for pp_div_reg
>
> Signed-off-by: Clint Taylor <clinton.a.taylor@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c  |   43 ++++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/i915/intel_drv.h |    1 +
>  2 files changed, 44 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 5ca68aa9..023efda 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>
> @@ -302,6 +304,39 @@ 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 gaurantee T12 timing */

guarantee

> +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 intel_digital_port *intel_dig_port = dp_to_dig_port(intel_dp);
> +	struct drm_device *dev = intel_dig_port->base.base.dev;
> +	struct drm_i915_private *dev_priv = dev->dev_private;
> +	u32 pp;
> +	u32 pp_ctrl_reg, pp_div_reg;
> +	enum pipe pipe = vlv_power_sequencer_pipe(intel_dp);
> +
> +	if (!is_edp(intel_dp))
> +		return 0;
> +
> +	if (IS_VALLEYVIEW(dev)) {
> +		pp_ctrl_reg = VLV_PIPE_PP_CONTROL(pipe);
> +		pp_div_reg  = VLV_PIPE_PP_DIVISOR(pipe);
> +		if (code == SYS_RESTART) {

Check for code != SYS_RESTART along with !is_edp above and bail out
early.

> +			pp = I915_READ(VLV_PIPE_PP_DIVISOR(pipe));

Elsewhere pp is used for the control reg. Please use pp_div instead.

You use pp_div_reg inconsistently; the above doesn't have it. (I think
you could drop the temp vars for regs here completely, but up to you.)

> +			pp &= PP_REFERENCE_DIVIDER_MASK;
> +			/* 0x1F write to PP_DIV_REG sets max cycle delay */
> +			I915_WRITE(pp_div_reg , pp | 0x1F);
> +			I915_WRITE(pp_ctrl_reg,
> +					   PANEL_UNLOCK_REGS | PANEL_POWER_OFF);
> +			/* VBT entries are in tenths of uS convert to mS */

Use s for seconds; S is Siemens. But really, drop the comment
altogether because...

> +			msleep(dev_priv->vbt.edp_pps.t11_t12 / 10);

I think you should use msleep(intel_dp->panel_power_cycle_delay)
instead. The units are already taken care of, and it has fallbacks for
when VBT is bogus or zero.

> +		}
> +	}
> +	return 0;
> +}
> +
>  static bool edp_have_panel_power(struct intel_dp *intel_dp)
>  {
>  	struct drm_device *dev = intel_dp_to_dev(intel_dp);
> @@ -3344,6 +3379,10 @@ void intel_dp_encoder_destroy(struct drm_encoder *encoder)
>  		mutex_lock(&dev->mode_config.mutex);
>  		edp_panel_vdd_off_sync(intel_dp);
>  		mutex_unlock(&dev->mode_config.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);
>  }
> @@ -3782,6 +3821,10 @@ 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 328b1a7..1ea193a 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -512,6 +512,7 @@ struct intel_dp {
>  	bool psr_setup_done;
>  	bool use_tps3;
>  	struct intel_connector *attached_connector;
> +	struct notifier_block  edp_notifier;

This belongs after psr_setup_done field, preferrably add a space after
them to separate edp stuff from the rest. (I think we should have a sub
struct for edp in the long run.)

BR,
Jani.

>  
>  	uint32_t (*get_aux_clock_divider)(struct intel_dp *dp, int index);
>  	/*
> -- 
> 1.7.9.5
>
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-- 
Jani Nikula, Intel Open Source Technology Center