[Intel-gfx] [PATCH] drm/i915: edp resume/On time optimization.

[Ville Syrjälä]

On Mon, Dec 21, 2015 at 05:18:52PM -0800, abhay.kumar at intel.com wrote:
> From: Abhay Kumar <abhay.kumar at intel.com>
> 
> Make resume/on codepath not to wait for panel_power_cycle_delay(t11_t12)
> if this time is already spent in suspend/poweron time.
> 
> v2: Use CLOCK_BOOTTIME and remove jiffies for panel power cycle
>     delay calculation(Ville).

The approach seems reasonable enough to me. There are a few issues with
the patch though, see below.

> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Abhay Kumar <abhay.kumar at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_ddi.c |  3 +++
>  drivers/gpu/drm/i915/intel_dp.c  | 22 ++++++++++++++--------
>  drivers/gpu/drm/i915/intel_drv.h |  2 +-
>  3 files changed, 18 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
> index e6408e5..480697d 100644
> --- a/drivers/gpu/drm/i915/intel_ddi.c
> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> @@ -2395,6 +2395,9 @@ static void intel_ddi_post_disable(struct intel_encoder *intel_encoder)
>  		intel_dp_sink_dpms(intel_dp, DRM_MODE_DPMS_OFF);
>  		intel_edp_panel_vdd_on(intel_dp);
>  		intel_edp_panel_off(intel_dp);
> +
> +		/* storing panel power off time */

The comment seems rather pointless.

> +		intel_dp->panel_power_off_time = ktime_get_with_offset(TK_OFFS_BOOT);

There appears to be a wrapper for this: ktime_get_boottime().

Not sure why you're adding this here anyway. Should be enough to just
replace the places where we currently sample jiffies to sample the boot
clock AFAICS.

>  	}
>  
>  	if (IS_SKYLAKE(dev) || IS_KABYLAKE(dev))
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 796e3d3..c813605 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -38,7 +38,6 @@
>  #include "intel_drv.h"
>  #include <drm/i915_drm.h>
>  #include "i915_drv.h"
> -

Spurious change.

>  #define DP_LINK_CHECK_TIMEOUT	(10 * 1000)
>  
>  /* Compliance test status bits  */
> @@ -1812,13 +1811,22 @@ static void wait_panel_off(struct intel_dp *intel_dp)
>  
>  static void wait_panel_power_cycle(struct intel_dp *intel_dp)
>  {
> +	ktime_t panel_power_on_time;
> +	u32 panel_power_off_duration;
> +
>  	DRM_DEBUG_KMS("Wait for panel power cycle\n");
>  
> -	/* When we disable the VDD override bit last we have to do the manual
> -	 * wait. */
> -	wait_remaining_ms_from_jiffies(intel_dp->last_power_cycle,
> -				       intel_dp->panel_power_cycle_delay);
> +        /* take the diffrence of currrent time and panel power off time
> +           and then make panel wait for t11_t12 if needed */

Indent fail. Also the comment isn't in proper format.

> +	panel_power_on_time = ktime_get_with_offset(TK_OFFS_BOOT);
> +	panel_power_off_duration = (panel_power_on_time.tv64 - intel_dp->panel_power_off_time.tv64);
> +	panel_power_off_duration = panel_power_off_duration / 1000000;

ktime_ms_delta() perhaps?

>  
> +	/* When we disable the VDD override bit last we have to do the manual
> +	 * wait */

This comment formatting is a bit wonky too. Maybe polish it up while at
it.

> +	if (panel_power_off_duration < intel_dp->panel_power_cycle_delay)
> +		wait_remaining_ms_from_jiffies(jiffies,
> +				       (intel_dp->panel_power_cycle_delay - panel_power_off_duration));
>  	wait_panel_status(intel_dp, IDLE_CYCLE_MASK, IDLE_CYCLE_VALUE);
>  }
>  
> @@ -1969,7 +1977,7 @@ static void edp_panel_vdd_off_sync(struct intel_dp *intel_dp)
>  	I915_READ(pp_stat_reg), I915_READ(pp_ctrl_reg));
>  
>  	if ((pp & POWER_TARGET_ON) == 0)
> -		intel_dp->last_power_cycle = jiffies;
> +		intel_dp->panel_power_off_time = ktime_get_with_offset(TK_OFFS_BOOT);
>  
>  	power_domain = intel_display_port_aux_power_domain(intel_encoder);
>  	intel_display_power_put(dev_priv, power_domain);
> @@ -2118,7 +2126,6 @@ static void edp_panel_off(struct intel_dp *intel_dp)
>  	I915_WRITE(pp_ctrl_reg, pp);
>  	POSTING_READ(pp_ctrl_reg);
>  
> -	intel_dp->last_power_cycle = jiffies;

Removing this doens't seem correct. Instead we should sample the clock
here as well.

>  	wait_panel_off(intel_dp);
>  
>  	/* We got a reference when we enabled the VDD. */
> @@ -5122,7 +5129,6 @@ intel_dp_add_properties(struct intel_dp *intel_dp, struct drm_connector *connect
>  
>  static void intel_dp_init_panel_power_timestamps(struct intel_dp *intel_dp)
>  {
> -	intel_dp->last_power_cycle = jiffies;

and I suppose here too.

>  	intel_dp->last_power_on = jiffies;
>  	intel_dp->last_backlight_off = jiffies;
>  }
> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> index d523ebb..84ad134 100644
> --- a/drivers/gpu/drm/i915/intel_drv.h
> +++ b/drivers/gpu/drm/i915/intel_drv.h
> @@ -765,9 +765,9 @@ struct intel_dp {
>  	int backlight_off_delay;
>  	struct delayed_work panel_vdd_work;
>  	bool want_panel_vdd;
> -	unsigned long last_power_cycle;
>  	unsigned long last_power_on;
>  	unsigned long last_backlight_off;
> +	ktime_t panel_power_off_time;
>  
>  	struct notifier_block edp_notifier;
>  
> -- 
> 1.9.1

-- 
Ville Syrjälä
Intel OTC