Re: [PATCH v8 3/5] drm/i915: Add option to support dynamic backlight via DPCD

From: "Pandiyan, Dhinakaran" <dhinakaran.pandiyan@intel.com>
To: Puthikorn Voravootivat <puthik@chromium.org>
Cc: "intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>
Subject: Re: [PATCH v8 3/5] drm/i915: Add option to support dynamic backlight via DPCD
Date: Tue, 23 May 2017 20:55:35 +0000	[thread overview]
Message-ID: <C56C55B681623645A065C9EE352337D611132D50@ORSMSX109.amr.corp.intel.com> (raw)
In-Reply-To: <CANCcNXcT9zWuOA8Es-5jXydS0FzGr98dqGppMjqACGp-2YHLgg@mail.gmail.com>

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Yeah, looks fine to me.

-DK

From: puthik@google.com [mailto:puthik@google.com] On Behalf Of Puthikorn Voravootivat
Sent: Friday, May 19, 2017 2:00 PM
To: Pandiyan, Dhinakaran <dhinakaran.pandiyan@intel.com>
Cc: puthik@chromium.org; dri-devel@lists.freedesktop.org; intel-gfx@lists.freedesktop.org; jani.nikula@linux.intel.com
Subject: Re: [Intel-gfx] [PATCH v8 3/5] drm/i915: Add option to support dynamic backlight via DPCD

Hi Dhinakaran,

Quick question

So what is the update about adding new option in i915_params?
Is this patch good to go after fixing the 2 points you mentioned?

Thanks

On Wed, May 17, 2017 at 1:33 PM, Pandiyan, Dhinakaran <dhinakaran.pandiyan@intel.com<mailto:dhinakaran.pandiyan@intel.com>> wrote:
On Tue, 2017-05-16 at 17:34 -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.
>
> Signed-off-by: Puthikorn Voravootivat <puthik@chromium.org<mailto:puthik@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 | 40 +++++++++++++++++++++++----
>  3 files changed, 41 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
> index 13cf3f1572ab..6eaf660e74da 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 = false,
>  };
>
>  module_param_named(modeset, i915.modeset, int, 0400);
> @@ -255,3 +256,7 @@ 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(enable_dbc, i915.enable_dbc, bool, 0600);
> +MODULE_PARM_DESC(enable_dbc,
> +     "Enable support for dynamic backlight control (default:false)");
> diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
> index ac02efce6e22..2de3e2850b54 100644
> --- a/drivers/gpu/drm/i915/i915_params.h
> +++ b/drivers/gpu/drm/i915/i915_params.h
> @@ -67,7 +67,8 @@
>       func(bool, nuclear_pageflip); \
>       func(bool, enable_dp_mst); \
>       func(int, enable_dpcd_backlight); \
> -     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 16ba1924308d..c0eeb8fc2013 100644
> --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> @@ -100,10 +100,27 @@ intel_dp_aux_set_backlight(struct intel_connector *connector, u32 level)
>       }
>  }
>
> +/*
> + * Set minimum / maximum dynamic brightness percentage. This value is expressed
> + * as the percentage of normal brightness in 5% increments.
> + */
> +static void
> +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)) {
Incorrect parentheses placement and return value check.

> +             DRM_DEBUG_KMS("Failed to write aux DBC brightness level\n");
> +     }
> +}
> +
>  static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
>  {
>       struct intel_dp *intel_dp = enc_to_intel_dp(&connector->encoder->base);
>       uint8_t dpcd_buf = 0;
> +     uint8_t new_dpcd_buf = 0;

nit: unnecessary initialization.

>       uint8_t edp_backlight_mode = 0;
>
>       if (drm_dp_dpcd_readb(&intel_dp->aux,
> @@ -113,18 +130,15 @@ static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
>               return;
>       }
>
> +     new_dpcd_buf = dpcd_buf;
>       edp_backlight_mode = dpcd_buf & DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
>
>       switch (edp_backlight_mode) {
>       case DP_EDP_BACKLIGHT_CONTROL_MODE_PWM:
>       case DP_EDP_BACKLIGHT_CONTROL_MODE_PRESET:
>       case DP_EDP_BACKLIGHT_CONTROL_MODE_PRODUCT:
> -             dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> -             dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
> -             if (drm_dp_dpcd_writeb(&intel_dp->aux,
> -                     DP_EDP_BACKLIGHT_MODE_SET_REGISTER, dpcd_buf) < 0) {
> -                     DRM_DEBUG_KMS("Failed to write aux backlight mode\n");
> -             }
> +             new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
> +             new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
>               break;
>
>       /* Do nothing when it is already DPCD mode */
> @@ -133,6 +147,20 @@ static void intel_dp_aux_enable_backlight(struct intel_connector *connector)
>               break;
>       }
>
> +     if (i915.enable_dbc &&
> +         (intel_dp->edp_dpcd[2] & DP_EDP_DYNAMIC_BACKLIGHT_CAP)) {
> +             new_dpcd_buf |= DP_EDP_DYNAMIC_BACKLIGHT_ENABLE;
> +             intel_dp_aux_set_dynamic_backlight_percent(intel_dp, 0, 100);
> +             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) {
> +                     DRM_DEBUG_KMS("Failed to write aux backlight mode\n");
> +             }
> +     }
> +
>       set_aux_backlight_enable(intel_dp, true);
>       intel_dp_aux_set_backlight(connector, connector->panel.backlight.level);
>  }

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