[Intel-gfx] [PATCH v10 2/3] drm/i915: Add option to support dynamic backlight via DPCD
Puthikorn Voravootivat
puthik at chromium.org
Wed May 31 21:37:29 UTC 2017
On Tue, May 30, 2017 at 9:18 PM, Pandiyan, Dhinakaran <
dhinakaran.pandiyan at intel.com> wrote:
> On Fri, 2017-05-26 at 18:42 -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 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 | 42
> ++++++++++++++++++++++-----
> > 3 files changed, 41 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_params.c
> b/drivers/gpu/drm/i915/i915_params.c
> > index 3758ae1f11b4..ce033d58134e 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,
>
> Based on Daniel's earlier comments on module parameters, shouldn't this
> be enabled by default too?
>
Yes. Will do.
>
> Or even more importantly, is this the right approach to enable/disable
> dynamic back light control? The reason I recommended having some sort of
> control to disable/enable is that the eDP spec. says the feature can
> have user visible impact.
>
I don't think we should expect end user to set this correctly. For power
user,
I think the i915_params is adequate. I don't want to add more complication
to the driver.
>
> Table 10-3 Display Control Capabilities
>
> "While the DBC control bit’s function is defined in this
> Standard, DBC implementation specifics are not defined, including
> interaction with other DPCD register settings. The DBC implementation,
> visual performance, and power savings characteristics can differ between
> specific panels."
>
> -DK
>
> > };
> >
> > 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: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 c89aae804659..f55af41ce3bd 100644
> > --- a/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> > +++ b/drivers/gpu/drm/i915/intel_dp_aux_backlight.c
> > @@ -100,11 +100,26 @@ 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) {
> > + 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 edp_backlight_mode = 0;
> > + uint8_t dpcd_buf, new_dpcd_buf, edp_backlight_mode;
> >
> > if (drm_dp_dpcd_readb(&intel_dp->aux,
> > DP_EDP_BACKLIGHT_MODE_SET_REGISTER, &dpcd_buf) !=
> 1) {
> > @@ -113,18 +128,15 @@ 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 +145,20 @@ 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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