[Intel-gfx] [PATCH v11 3/3] drm/i915: Add option to support dynamic backlight via DPCD

[Puthikorn Voravootivat]

Sorry forgot to remove Gerrit Change-ID before sending the email.

Do you want me to send the same patches again with your reviewed-by tag and
the Gerrit change-Id removed?

On Mon, Jun 5, 2017 at 11:49 AM, Pandiyan, Dhinakaran <
dhinakaran.pandiyan at intel.com> wrote:

> On Fri, 2017-06-02 at 19:04 -0700, Puthikorn Voravootivat wrote:
> > This patch adds option to enable dynamic backlight for eDP
> > panel that supports this feature via DPCD register and
> > set minimum / maximum brightness to 0% and 100% of the
> > normal brightness.
> >
> > Change-Id: I52f04b814bb4cd9df570ab59094ae974b9baec5b
> > Signed-off-by: Puthikorn Voravootivat <puthik at chromium.org>
> > ---
> >  drivers/gpu/drm/i915/i915_params.c            |  5 +++++
> >  drivers/gpu/drm/i915/i915_params.h            |  3 ++-
> >  drivers/gpu/drm/i915/intel_dp_aux_backlight.c | 26
> ++++++++++++++++++++++++++
> >  3 files changed, 33 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_params.c
> b/drivers/gpu/drm/i915/i915_params.c
> > index 3758ae1f11b4..d84042ddf1fc 100644
> > --- a/drivers/gpu/drm/i915/i915_params.c
> > +++ b/drivers/gpu/drm/i915/i915_params.c
> > @@ -65,6 +65,7 @@ struct i915_params i915 __read_mostly = {
> >       .inject_load_failure = 0,
> >       .enable_dpcd_backlight = -1,
> >       .enable_gvt = false,
> > +     .enable_dbc = true,
> >  };
> >
> >  module_param_named(modeset, i915.modeset, int, 0400);
> > @@ -254,3 +255,7 @@ MODULE_PARM_DESC(enable_dpcd_backlight,
> >  module_param_named(enable_gvt, i915.enable_gvt, bool, 0400);
> >  MODULE_PARM_DESC(enable_gvt,
> >       "Enable support for Intel GVT-g graphics virtualization host
> support(default:false)");
> > +
> > +module_param_named_unsafe(enable_dbc, i915.enable_dbc, bool, 0600);
> > +MODULE_PARM_DESC(enable_dbc,
> > +     "Enable support for dynamic backlight control (default:true)");
> > diff --git a/drivers/gpu/drm/i915/i915_params.h
> b/drivers/gpu/drm/i915/i915_params.h
> > index 643dfaf41c1f..99f68d853c18 100644
> > --- a/drivers/gpu/drm/i915/i915_params.h
> > +++ b/drivers/gpu/drm/i915/i915_params.h
> > @@ -67,7 +67,8 @@
> >       func(bool, verbose_state_checks); \
> >       func(bool, nuclear_pageflip); \
> >       func(bool, enable_dp_mst); \
> > -     func(bool, enable_gvt)
> > +     func(bool, enable_gvt); \
> > +     func(bool, enable_dbc)
> >
> >  #define MEMBER(T, member) T member
> >  struct i915_params {
> > diff --git a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> > index b73b3d431a82..b2f4cc975a3e 100644
> > --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> > +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> > @@ -172,6 +172,24 @@ static bool intel_dp_aux_set_pwm_freq(struct
> intel_connector *connector)
> >       return true;
> >  }
> >
> > +/*
> > +* Set minimum / maximum dynamic brightness percentage. This value is
> expressed
> > +* as the percentage of normal brightness in 5% increments.
> > +*/
> > +static bool
> > +intel_dp_aux_set_dynamic_backlight_percent(struct intel_dp *intel_dp,
> > +                                        u32 min, u32 max)
> > +{
> > +     u8 dbc[] = { DIV_ROUND_CLOSEST(min, 5), DIV_ROUND_CLOSEST(max, 5)
> };
> > +
> > +     if (drm_dp_dpcd_write(&intel_dp->aux,
> DP_EDP_DBC_MINIMUM_BRIGHTNESS_SET,
> > +                       dbc, sizeof(dbc)) < 0) {
> > +             DRM_DEBUG_KMS("Failed to write aux DBC brightness
> level\n");
> > +             return false;
> > +     }
> > +     return true;
> > +}
> > +
> >  static void intel_dp_aux_enable_backlight(struct intel_connector
> *connector)
> >  {
> >       struct intel_dp *intel_dp = enc_to_intel_dp(&connector->
> encoder->base);
> > @@ -205,6 +223,14 @@ static void intel_dp_aux_enable_backlight(struct
> intel_connector *connector)
> >               if (intel_dp_aux_set_pwm_freq(connector))
> >                       new_dpcd_buf |= DP_EDP_BACKLIGHT_FREQ_AUX_SET_
> ENABLE;
> >
> > +     if (i915.enable_dbc &&
> > +         (intel_dp->edp_dpcd[2] & DP_EDP_DYNAMIC_BACKLIGHT_CAP)) {
> > +             if(intel_dp_aux_set_dynamic_backlight_percent(intel_dp,
> 0, 100)) {
> > +                     new_dpcd_buf |= DP_EDP_DYNAMIC_BACKLIGHT_ENABLE;
> > +                     DRM_DEBUG_KMS("Enable dynamic brightness.\n");
> > +             }
> > +     }
> > +
> >       if (new_dpcd_buf != dpcd_buf) {
> >               if (drm_dp_dpcd_writeb(&intel_dp->aux,
> >                       DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf)
> < 0) {
>
> 1) The Gerrit Change-ID's you've added in this version *may* be a
> problem, haven't seen any patches here with those before.
> 2) The PWM v/s AUX heuristics function looks likes a reasonable start
> that can be adjusted later. We should be taking into account the number
> of brightness levels b/w PWM pin and AUX options IMO.
> 3) The DPCD r/w needs optimization.
>
> However things lgtm for now. So,
> Reviewed-by: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com> for
> this series.
>
>
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