> -----Original Message-----
> From: Sebastian Wick <sebastian.wick@xxxxxxxxxx>
> Sent: Wednesday, April 17, 2024 3:54 PM
> To: Kandpal, Suraj <suraj.kandpal@xxxxxxxxx>
> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Borah, Chaitanya Kumar
> <chaitanya.kumar.borah@xxxxxxxxx>; Shankar, Uma
> <uma.shankar@xxxxxxxxx>; Nautiyal, Ankit K <ankit.k.nautiyal@xxxxxxxxx>;
> Murthy, Arun R <arun.r.murthy@xxxxxxxxx>; Nikula, Jani
> <jani.nikula@xxxxxxxxx>; Kumar, Naveen1 <naveen1.kumar@xxxxxxxxx>
> Subject: Re: [5/6] drm/i915/dp: Enable AUX based backlight for HDR
>
> On Wed, Apr 17, 2024 at 04:58:06AM +0000, Kandpal, Suraj wrote:
> >
> >
> > > -----Original Message-----
> > > From: Sebastian Wick <sebastian.wick@xxxxxxxxxx>
> > > Sent: Tuesday, April 16, 2024 7:10 PM
> > > To: Kandpal, Suraj <suraj.kandpal@xxxxxxxxx>
> > > Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx; Borah, Chaitanya Kumar
> > > <chaitanya.kumar.borah@xxxxxxxxx>; Shankar, Uma
> > > <uma.shankar@xxxxxxxxx>; Nautiyal, Ankit K
> > > <ankit.k.nautiyal@xxxxxxxxx>; Murthy, Arun R
> > > <arun.r.murthy@xxxxxxxxx>; Nikula, Jani <jani.nikula@xxxxxxxxx>;
> > > Kumar, Naveen1 <naveen1.kumar@xxxxxxxxx>
> > > Subject: Re: [5/6] drm/i915/dp: Enable AUX based backlight for HDR
> > >
> > > On Thu, Apr 11, 2024 at 11:39:24AM +0530, Suraj Kandpal wrote:
> > > > As of now whenerver HDR is switched on we use the PWM to change
> > > > the backlight as opposed to AUX based backlight changes in terms of
> nits.
> > > > This patch writes to the appropriate DPCD registers to enable aux
> > > > based backlight using values in nits.
> > > >
> > > > --v2
> > > > -Fix max_cll and max_fall assignment [Jani] -Fix the size sent in
> > > > drm_dpcd_write [Jani]
> > > >
> > > > --v3
> > > > -Content Luminance needs to be sent only for pre-ICL after that it
> > > > is directly picked up from hdr metadata [Ville]
> > > >
> > > > --v4
> > > > -Add checks for HDR TCON cap bits [Ville] -Check eotf of
> > > > hdr_output_data and sets bits base of that value.
> > > >
> > > > --v5
> > > > -Fix capability check bits.
> > > > -Check colorspace before setting BT2020
> > > >
> > > > --v6
> > > > -Use intel_dp_has_gamut_dip to check if we have capability to send
> > > > sdp [Ville] -Seprate filling of all hdr tcon related bits into
> > > > it's own function.
> > > > -Check eotf data to make sure we are in HDR mode [Sebastian]
> > > >
> > > > --v7
> > > > -Fix confusion function name for hdr mode check [Jani] -Fix the
> > > > condition which tells us if we are in HDR mode or not [Sebastian]
> > > >
> > > > Signed-off-by: Suraj Kandpal <suraj.kandpal@xxxxxxxxx>
> > > > ---
> > > > .../drm/i915/display/intel_dp_aux_backlight.c | 105
> > > > ++++++++++++++++--
> > > > 1 file changed, 94 insertions(+), 11 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> > > > b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> > > > index b61bad218994..b13eee250dc4 100644
> > > > --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> > > > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
> > > > @@ -40,11 +40,6 @@
> > > > #include "intel_dp.h"
> > > > #include "intel_dp_aux_backlight.h"
> > > >
> > > > -/* TODO:
> > > > - * Implement HDR, right now we just implement the bare minimum to
> > > > bring us back into SDR mode so we
> > > > - * can make people's backlights work in the mean time
> > > > - */
> > > > -
> > > > /*
> > > > * DP AUX registers for Intel's proprietary HDR backlight interface. We
> define
> > > > * them here since we'll likely be the only driver to ever use these.
> > > > @@ -127,9 +122,6 @@ intel_dp_aux_supports_hdr_backlight(struct
> > > intel_connector *connector)
> > > > if (ret != sizeof(tcon_cap))
> > > > return false;
> > > >
> > > > - if (!(tcon_cap[1] & INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP))
> > > > - return false;
> > > > -
> > > > drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] Detected %s HDR
> > > backlight interface version %d\n",
> > > > connector->base.base.id, connector->base.name,
> > > > is_intel_tcon_cap(tcon_cap) ? "Intel" : "unsupported",
> > > > tcon_cap[0]); @@ -137,6 +129,9 @@
> > > intel_dp_aux_supports_hdr_backlight(struct intel_connector
> > > *connector)
> > > > if (!is_intel_tcon_cap(tcon_cap))
> > > > return false;
> > > >
> > > > + if (!(tcon_cap[1] & INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP))
> > > > + return false;
> > > > +
> > > > /*
> > > > * If we don't have HDR static metadata there is no way to
> > > > * runtime detect used range for nits based control. For now @@
> > > > -225,13 +220,27 @@ intel_dp_aux_hdr_set_aux_backlight(const struct
> > > drm_connector_state *conn_state,
> > > > connector->base.base.id, connector->base.name); }
> > > >
> > > > +static bool
> > > > +intel_dp_in_hdr_mode(const struct drm_connector_state *conn_state)
> {
> > > > + struct hdr_output_metadata *hdr_metadata;
> > > > +
> > > > + if (!conn_state->hdr_output_metadata)
> > > > + return false;
> > > > +
> > > > + hdr_metadata = conn_state->hdr_output_metadata->data;
> > > > +
> > > > + return hdr_metadata->hdmi_metadata_type1.eotf ==
> > > > +HDMI_EOTF_SMPTE_ST2084; }
> > > > +
> > > > static void
> > > > intel_dp_aux_hdr_set_backlight(const struct drm_connector_state
> > > >*conn_state, u32 level) {
> > > > struct intel_connector *connector =
> > > >to_intel_connector(conn_state- connector);
> > > > struct intel_panel *panel = &connector->panel;
> > > >
> > > > - if (panel->backlight.edp.intel.sdr_uses_aux) {
> > > > + if (intel_dp_in_hdr_mode(conn_state) ||
> > > > + panel->backlight.edp.intel.sdr_uses_aux) {
> > > > intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
> > > > } else {
> > > > const u32 pwm_level =
> > > intel_backlight_level_to_pwm(connector,
> > > > level); @@ -240,6 +249,70 @@ intel_dp_aux_hdr_set_backlight(const
> > > struct drm_connector_state *conn_state, u32
> > > > }
> > > > }
> > > >
> > > > +static void
> > > > +intel_dp_aux_write_content_luminance(struct intel_connector
> *connector,
> > > > + struct hdr_output_metadata
> > > *hdr_metadata) {
> > > > + struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
> > > > + struct drm_i915_private *i915 = to_i915(connector->base.dev);
> > > > + int ret;
> > > > + u8 buf[4];
> > > > +
> > > > + if (!intel_dp_has_gamut_metadata_dip(connector->encoder))
> > > > + return;
> > > > +
> > > > + buf[0] = hdr_metadata->hdmi_metadata_type1.max_cll & 0xFF;
> > > > + buf[1] = (hdr_metadata->hdmi_metadata_type1.max_cll & 0xFF00)
> > > >> 8;
> > > > + buf[2] = hdr_metadata->hdmi_metadata_type1.max_fall & 0xFF;
> > > > + buf[3] = (hdr_metadata->hdmi_metadata_type1.max_fall & 0xFF00)
> > > >> 8;
> > > > +
> > > > + ret = drm_dp_dpcd_write(&intel_dp->aux,
> > > > + INTEL_EDP_HDR_CONTENT_LUMINANCE,
> > > > + buf, sizeof(buf));
> > > > + if (ret < 0)
> > > > + drm_dbg_kms(&i915->drm,
> > > > + "Content Luminance DPCD reg write failed, err:-
> > > %d\n",
> > > > + ret);
> > > > +}
> > > > +
> > > > +static void
> > > > +intel_dp_aux_fill_hdr_tcon_params(const struct
> > > > +drm_connector_state *conn_state, u8 *ctrl) {
> > > > + struct intel_connector *connector =
> > > > +to_intel_connector(conn_state-
> > > >connector);
> > > > + struct intel_panel *panel = &connector->panel;
> > > > + struct drm_i915_private *i915 = to_i915(connector->base.dev);
> > > > + struct hdr_output_metadata *hdr_metadata =
> > > > +conn_state->hdr_output_metadata->data;
> > > > +
> > > > + /* According to spec segmented backlight needs to be set
> > > > +whenever
> > > panel is in
> > > > + * HDR mode.
> > > > + */
> > > > + *ctrl |= INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_ENABLE;
> > > > +
> > > > + /* 2084 decode needs to set if eotf suggests so or in case of
> > > > +pre-ICL
> > > we disable
> > > > + * tone mapping and set 2084 decode.
> > > > + */
> > > > + if (hdr_metadata->hdmi_metadata_type1.eotf ==
> > > > + HDMI_EOTF_SMPTE_ST2084 || DISPLAY_VER(i915) < 11) {
> > >
> > > this function only gets called when eotf == HDMI_EOTF_SMPTE_ST2084
> > > which means all of this is qeuivalent to
> > >
> > > *ctrl |= INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_ENABLE;
> > > *ctrl |= INTEL_EDP_HDR_TCON_2084_DECODE_ENABLE;
> > > *ctrl &= ~INTEL_EDP_HDR_TCON_TONE_MAPPING_ENABLE;
> > >
> >
> > Right will drop the SMPTE check altogether
> >
> > > The comment about pre-ICL is also really confusing to me, especially
> > > because it doesn't actually change the semantics. Can you explain
> > > what you're trying to achieve here?
> > >
> >
> > Spec states that we need to disable Tone mapping pre-ICL and after
> > that it will Be TCON's decision to enable TM based on panel override
> > values
>
> Right, but the TCON will just ignore it so you always set it.
>
Sure will rework this patch a little
> >
> > > > + *ctrl |= INTEL_EDP_HDR_TCON_2084_DECODE_ENABLE;
> > > > + *ctrl &= ~INTEL_EDP_HDR_TCON_TONE_MAPPING_ENABLE;
> > > > + } else {
> > > > + drm_dbg_kms(&i915->drm, "[CONNECTOR:%d:%s] TCON:
> > > Cannot decode requested EOTF\n",
> > > > + connector->base.base.id, connector->base.name);
> > > > + }
> > > > +
> > > > + if (panel->backlight.edp.intel.supports_2020_gamut &&
> > > > + (conn_state->colorspace ==
> > > DRM_MODE_COLORIMETRY_BT2020_RGB ||
> > > > + conn_state->colorspace ==
> > > DRM_MODE_COLORIMETRY_BT2020_YCC ||
> > > > + conn_state->colorspace ==
> > > DRM_MODE_COLORIMETRY_BT2020_CYCC))
> > > > + *ctrl |= INTEL_EDP_HDR_TCON_2020_GAMUT_ENABLE;
> > >
> > > The Colorspace prop can be set independently of the
> > > HDR_OUTPUT_METADATA prop but this only enables the bt2020 gamut
> when
> > > in HDR mode
> > > (intel_dp_in_hdr_mode() == true).
> > >
> >
> > there's only two states in the DPCD register Standard gamma and bt2020
> > now this case here is specific to when we are in HDR mode and do not
> > want to write in this register when not in HDR mode.
>
> That doesn't seem right. bt2020 gamut is completely independent of 2084
> decode and segmented backlight (i.e. HDR mode). From a uAPI perspective
> when the Colorspace prop is set to bt2020 we need the sink to expect
> bt2020 content, no matter any other property.
>
> The question really is if on devices with the TCON are you able to get it to
> process bt2020 without setting
> INTEL_EDP_HDR_TCON_2020_GAMUT_ENABLE? I don't believe so. From the
> testing we've done it looks like DPCD is ignored unless
> INTEL_EDP_HDR_TCON_SDP_OVERRIDE_AUX is set.
>
> >
> > > > +
> > > > + if (panel->backlight.edp.intel.supports_sdp_colorimetry &&
> > > > + intel_dp_has_gamut_metadata_dip(connector->encoder))
> > > > + *ctrl |= INTEL_EDP_HDR_TCON_SDP_OVERRIDE_AUX;
> > > > + else
> > > > + *ctrl &= ~INTEL_EDP_HDR_TCON_SDP_OVERRIDE_AUX;
> > > > +}
> > > > +
> > > > static void
> > > > intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state
> *crtc_state,
> > > > const struct drm_connector_state
> > > *conn_state, u32 level) @@
> > > > -248,6 +321,7 @@ intel_dp_aux_hdr_enable_backlight(const struct
> > > intel_crtc_state *crtc_state,
> > > > struct intel_panel *panel = &connector->panel;
> > > > struct drm_i915_private *i915 = to_i915(connector->base.dev);
> > > > struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
> > > > + struct hdr_output_metadata *hdr_metadata;
> > > > int ret;
> > > > u8 old_ctrl, ctrl;
> > > >
> > > > @@ -261,8 +335,10 @@ intel_dp_aux_hdr_enable_backlight(const
> > > > struct
> > > intel_crtc_state *crtc_state,
> > > > }
> > > >
> > > > ctrl = old_ctrl;
> > > > - if (panel->backlight.edp.intel.sdr_uses_aux) {
> > > > + if (intel_dp_in_hdr_mode(conn_state) ||
> > > > + panel->backlight.edp.intel.sdr_uses_aux) {
> > > > ctrl |= INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
> > > > +
> > > > intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
> > > > } else {
> > > > u32 pwm_level = intel_backlight_level_to_pwm(connector,
> > > level); @@
> > > > -272,10 +348,18 @@ intel_dp_aux_hdr_enable_backlight(const struct
> > > intel_crtc_state *crtc_state,
> > > > ctrl &= ~INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
> > > > }
> > > >
> > > > + if (intel_dp_in_hdr_mode(conn_state))
> > > > + intel_dp_aux_fill_hdr_tcon_params(conn_state, &ctrl);
> > > > +
> > >
> > > I think you should call intel_dp_aux_fill_hdr_tcon_params
> > > unconditionally and in there have the logic like this:
> > >
> > > if (hdr_metadata->hdmi_metadata_type1.eotf ==
> > > HDMI_EOTF_SMPTE_ST2084) {
> > > *ctrl |= INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_ENABLE;
> > > *ctrl |= INTEL_EDP_HDR_TCON_2084_DECODE_ENABLE;
> > > *ctrl &= ~INTEL_EDP_HDR_TCON_TONE_MAPPING_ENABLE;
> > > }
> > > if (conn_state->colorspace == DRM_MODE_COLORIMETRY_BT2020_RGB
> ...) {
> > > *ctrl |= INTEL_EDP_HDR_TCON_2020_GAMUT_ENABLE;
> > > }
> > >
> >
> > I'll be dropping the condition inside the
> > intel_dp_aux_fill_hdr_tcon_params As writing to DPCD and filling in the
> params does not make sense until we are in HDR mode.
>
> See above. I believe HDR mode is just one thing you have to handle in the
> TCON and the gamut processing must be set independently.
>
Sure got your point will rework it to have bt 2020 gamut set regardess of when in hdr mode or not.
Regards,
Suraj Kandpal
> >
> > Regards,
> > Suraj Kandpal
> >
> > > > if (ctrl != old_ctrl &&
> > > > drm_dp_dpcd_writeb(&intel_dp->aux,
> > > INTEL_EDP_HDR_GETSET_CTRL_PARAMS, ctrl) != 1)
> > > > drm_err(&i915->drm, "[CONNECTOR:%d:%s] Failed to
> > > configure DPCD brightness controls\n",
> > > > connector->base.base.id, connector->base.name);
> > > > +
> > > > + if (intel_dp_in_hdr_mode(conn_state)) {
> > > > + hdr_metadata = conn_state->hdr_output_metadata->data;
> > > > + intel_dp_aux_write_content_luminance(connector,
> > > hdr_metadata);
> > > > + }
> > > > }
> > > >
> > > > static void
> > > > @@ -332,7 +416,6 @@ intel_dp_aux_hdr_setup_backlight(struct
> > > intel_connector *connector, enum pipe pi
> > > > connector->base.base.id, connector->base.name,
> > > > panel->backlight.min, panel->backlight.max);
> > > >
> > > > -
> > > > panel->backlight.level =
> > > > intel_dp_aux_hdr_get_backlight(connector,
> > > pipe);
> > > > panel->backlight.enabled = panel->backlight.level != 0;
> > > >
> >
