Re: [PATCH 6/6] drm/i915: set the backlight panel delays registers to 1

Jesse Barnes
2013-12-19T17:39:36Z

On Thu, 19 Dec 2013 14:29:44 -0200
Paulo Zanoni <przanoni@gmail.com> wrote:

> From: Paulo Zanoni <paulo.r.zanoni@intel.com>
>
> Because we already do the wait in software: see
> ironlake_wait_backlight_on and ironlake_edp_wait_backlight_off.
>
> For the "backlight on" delay, even BSpec says we need to program 0x1
> to PP_ON_DELAYS 12:0.
>
> For the "backlight off" delay, if we don't do the same thing, when we
> call ironlake_wait_panel_off we'll end up waiting for the it again.
>
> On my machine the off delay is 200ms, so we save this amount of time
> whenever we disable the panel (e.g, suspend).
>
> Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
> ---
> drivers/gpu/drm/i915/intel_dp.c | 13 ++++++++++---
> 1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 69d8f1c..90ff059 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -3535,10 +3535,17 @@ intel_dp_init_panel_power_sequencer_registers(struct drm_device *dev,
> pp_div_reg = VLV_PIPE_PP_DIVISOR(pipe);
> }
>
> - /* And finally store the new values in the power sequencer. */
> + /*
> + * And finally store the new values in the power sequencer. The
> + * backlight delays are set to 1 because we do manual waits on them. For
> + * T8, even BSpec recommends doing it. For T9, if we don't do this,
> + * we'll end up waiting for the backlight off delay twice: once when we
> + * do the manual sleep, and once when we disable the panel and wait for
> + * the PP_STATUS bit to become zero.
> + */
> pp_on = (seq->t1_t3 << PANEL_POWER_UP_DELAY_SHIFT) |
> - (seq->t8 << PANEL_LIGHT_ON_DELAY_SHIFT);
> - pp_off = (seq->t9 << PANEL_LIGHT_OFF_DELAY_SHIFT) |
> + (1 << PANEL_LIGHT_ON_DELAY_SHIFT);
> + pp_off = (1 << PANEL_LIGHT_OFF_DELAY_SHIFT) |
> (seq->t10 << PANEL_POWER_DOWN_DELAY_SHIFT);
> /* Compute the divisor for the pp clock, simply match the Bspec
> * formula. */

Yay!

Reviewed-by: Jesse Barnes <jbarnes@virtuousgeek.org>