Re: [PATCH] drm/i915/dp: Backlight PWM enable before BL Enable assert

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

On Fri, 15 Aug 2014, clinton.a.taylor@intel.com wrote:
> From: Clint Taylor <clinton.a.taylor@intel.com>
>
> Backlight on delay uses PWM enable time to seperate PWM to
> backlight enable assert. Previous time difference used timing
> from VDD enable which occur several seconds before resulting
> in PWM starting 5ms after backlight enable. Changes to backlight
>  duty cycle take affect at the end of the current PWM cycle.
> Measured time for the PWM cycle is 5ms. 5 additional ms must be
> added to the backlight_on_delay to get correct VBT timing of
> PWM to backlight enable assert.

The patch seems sane, but I'd like you to rebase this on top of patch
1/4 of my backlight series [1] so I can queue them both to
drm-intel-fixes. Then we'll have fewer conflicts with the rest of the
backlight series going forward.

Hint hint, I'd also appreciate review of my backlight series. ;)

BR,
Jani.


[1] http://mid.gmane.org/e7a47b50ed0f25cafdc26711fc09561ea8af3b81.1407849872.git.jani.nikula@intel.com


>
> Change-Id: I484999a597fd84dacf4cf99a168ec9ba4bb6ff11
> Signed-off-by: Clint Taylor <clinton.a.taylor@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c  | 6 ++++--
>  drivers/gpu/drm/i915/intel_drv.h | 1 +
>  2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index e5ada4f..c59ccdb 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -1141,7 +1141,7 @@ static void wait_panel_power_cycle(struct intel_dp *intel_dp)
>  
>  static void wait_backlight_on(struct intel_dp *intel_dp)
>  {
> -	wait_remaining_ms_from_jiffies(intel_dp->last_power_on,
> +	wait_remaining_ms_from_jiffies(intel_dp->last_backlight_on,
>  				       intel_dp->backlight_on_delay);
>  }
>  
> @@ -1398,6 +1398,7 @@ void intel_edp_backlight_on(struct intel_dp *intel_dp)
>  	DRM_DEBUG_KMS("\n");
>  
>  	intel_panel_enable_backlight(intel_dp->attached_connector);
> +	intel_dp->last_backlight_on = jiffies;
>  
>  	/*
>  	 * If we enable the backlight right away following a panel power
> @@ -4243,9 +4244,10 @@ intel_dp_init_panel_power_sequencer(struct drm_device *dev,
>  	assign_final(t11_t12);
>  #undef assign_final
>  
> +#define PWM_CYCLE_DELAY 5
>  #define get_delay(field)	(DIV_ROUND_UP(final.field, 10))
>  	intel_dp->panel_power_up_delay = get_delay(t1_t3);
> -	intel_dp->backlight_on_delay = get_delay(t8);
> +	intel_dp->backlight_on_delay = get_delay(t8) + PWM_CYCLE_DELAY;
>  	intel_dp->backlight_off_delay = get_delay(t9);
>  	intel_dp->panel_power_down_delay = get_delay(t10);
>  	intel_dp->panel_power_cycle_delay = get_delay(t11_t12);
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index 3abc915..ad6fcc1 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -556,6 +556,7 @@ struct intel_dp {
>  	bool want_panel_vdd;
>  	unsigned long last_power_cycle;
>  	unsigned long last_power_on;
> +	unsigned long last_backlight_on;
>  	unsigned long last_backlight_off;
>  
>  	struct notifier_block edp_notifier;
> -- 
> 1.8.3.2
>
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-- 
Jani Nikula, Intel Open Source Technology Center