On Fri, 2017-06-30 at 11:20 +0530, Sharma, Shashank wrote:
> Regards
>
> Shashank
>
>
> On 6/27/2017 5:46 PM, Ander Conselvan De Oliveira wrote:
> > On Wed, 2017-06-21 at 16:04 +0530, Shashank Sharma wrote:
> > > To get a YCBCR420 output from intel platforms, we need one
> > > scaler to scale down YCBCR444 samples to YCBCR420 samples.
> > >
> > > This patch:
> > > - Does scaler allocation for HDMI ycbcr420 outputs.
> > > - Programs PIPE_MISC register for ycbcr420 output.
> > > - Adds a new scaler user "HDMI output" to plug-into existing
> > > scaler framework. This output type is identified using bit
> > > 30 of the scaler users bitmap.
> > >
> > > V2: rebase
> > > V3: rebase
> > > V4: rebase
> > >
> > > Cc: Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx>
> > > Cc: Ander Conselvan De Oliveira <ander.conselvan.de.oliveira@xxxxxxxxx>
> > > Signed-off-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
> > > ---
> > > drivers/gpu/drm/i915/intel_atomic.c | 6 ++++++
> > > drivers/gpu/drm/i915/intel_display.c | 26 ++++++++++++++++++++++++++
> > > drivers/gpu/drm/i915/intel_drv.h | 10 +++++++++-
> > > drivers/gpu/drm/i915/intel_hdmi.c | 10 ++++++++++
> > > drivers/gpu/drm/i915/intel_panel.c | 3 ++-
> > > 5 files changed, 53 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_atomic.c b/drivers/gpu/drm/i915/intel_atomic.c
> > > index 36d4e63..a8c9ac5 100644
> > > --- a/drivers/gpu/drm/i915/intel_atomic.c
> > > +++ b/drivers/gpu/drm/i915/intel_atomic.c
> > > @@ -264,6 +264,12 @@ int intel_atomic_setup_scalers(struct drm_i915_private *dev_priv,
> > >
> > > /* panel fitter case: assign as a crtc scaler */
> > > scaler_id = &scaler_state->scaler_id;
> > > + } else if (i == SKL_HDMI_OUTPUT_INDEX) {
> > > + name = "HDMI-OUTPUT";
> > > + idx = intel_crtc->base.base.id;
> > > +
> > > + /* hdmi output case: needs a pipe scaler */
> > > + scaler_id = &scaler_state->scaler_id;
> > > } else {
> > > name = "PLANE";
> > >
> > > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > > index da29536..983f581 100644
> > > --- a/drivers/gpu/drm/i915/intel_display.c
> > > +++ b/drivers/gpu/drm/i915/intel_display.c
> > > @@ -4626,6 +4626,11 @@ skl_update_scaler(struct intel_crtc_state *crtc_state, bool force_detach,
> > > */
> > > need_scaling = src_w != dst_w || src_h != dst_h;
> > >
> > > + if (crtc_state->hdmi_output == DRM_HDMI_OUTPUT_YCBCR420
> > > + && scaler_user == SKL_HDMI_OUTPUT_INDEX)
> >
> > Is it really necessary to check for both? If it is, what's the point of creating
> > SKL_HDMI_OUTPUT_INDEX?
>
> Yes, else this will affect scaler update for planes, as this function
> gets called to update the plane scalers too, at that time the output
> will be still valid (as its at CRTC level), but the
> scaler user would be different.
Right, so there is a need to check for scaler_user == HDMI_OUTPUT. But then
wouldn't it be a bug if hdmi_output != YCBCR420 ? Point is, if the caller asked
for a HDMI_OUTPUT scaler hopefully it knows what its doing, no need to second
guess it.
> >
> > > + /* YCBCR 444 -> 420 conversion needs a scaler */
> > > + need_scaling = true;
> > > +
> > > /*
> > > * if plane is being disabled or scaler is no more required or force detach
> > > * - free scaler binded to this plane/crtc
> > > @@ -4673,6 +4678,26 @@ skl_update_scaler(struct intel_crtc_state *crtc_state, bool force_detach,
> > > }
> > >
> > > /**
> > > + * skl_update_scaler_hdmi_output - Stages update to scaler state for HDMI.
> > > + * HDMI YCBCR 420 output needs a scaler, for downsampling.
> > > + *
> > > + * @state: crtc's scaler state
> > > + *
> > > + * Return
> > > + * 0 - scaler_usage updated successfully
> > > + * error - requested scaling cannot be supported or other error condition
> > > + */
> > > +int skl_update_scaler_crtc_hdmi_output(struct intel_crtc_state *state)
> > > +{
> > > + const struct drm_display_mode *mode = &state->base.adjusted_mode;
> > > +
> > > + return skl_update_scaler(state, !state->base.active,
> > > + SKL_HDMI_OUTPUT_INDEX, &state->scaler_state.scaler_id,
> > > + state->pipe_src_w, state->pipe_src_h,
> > > + mode->crtc_hdisplay, mode->crtc_vdisplay);
> > > +}
> > > +
> > > +/**
> > > * skl_update_scaler_crtc - Stages update to scaler state for a given crtc.
> > > *
> > > * @state: crtc's scaler state
> > > @@ -8058,6 +8083,7 @@ static void haswell_set_pipemisc(struct drm_crtc *crtc)
> > > {
> > > struct drm_i915_private *dev_priv = to_i915(crtc->dev);
> > > struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
> > > + enum drm_hdmi_output_type hdmi_out = intel_crtc->config->hdmi_output;
> > >
> > > if (IS_BROADWELL(dev_priv) || INTEL_INFO(dev_priv)->gen >= 9) {
> > > u32 val = 0;
> > > diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
> > > index 38fe56c..2206aa8 100644
> > > --- a/drivers/gpu/drm/i915/intel_drv.h
> > > +++ b/drivers/gpu/drm/i915/intel_drv.h
> > > @@ -471,7 +471,8 @@ struct intel_crtc_scaler_state {
> > > *
> > > * If a bit is set, a user is using a scaler.
> > > * Here user can be a plane or crtc as defined below:
> > > - * bits 0-30 - plane (bit position is index from drm_plane_index)
> > > + * bits 0-29 - plane (bit position is index from drm_plane_index)
> > > + * bit 30 - hdmi output
> > > * bit 31 - crtc
> > > *
> > > * Instead of creating a new index to cover planes and crtc, using
> > > @@ -484,6 +485,12 @@ struct intel_crtc_scaler_state {
> > > * avilability.
> > > */
> > > #define SKL_CRTC_INDEX 31
> > > +
> > > + /*
> > > + * HDMI YCBCR 420 output consume a scaler. So adding a user
> > > + * for HDMI output 420 requirement.
> > > + */
> > > +#define SKL_HDMI_OUTPUT_INDEX 30
> >
> > I'm not convinced about this. The scaler is still used as a pipe scaler and the
> > patch even adds a call intel_pch_panel_fitting().
>
> This is a special mode usage of scalar defined in the bspec, when we
> want to run the scalar into 5x3 auto mode for YCBCR444->YCBCR420 scale down.
> It can be used only when the PIPE_MISC is also programmed to act
> accordingly. So this is different from using it as a panel fitter, and
> that's why added
> a new scalar user all together.
> >
> > > unsigned scaler_users;
> > >
> > > /* scaler used by crtc for panel fitting purpose */
> > > @@ -1481,6 +1488,7 @@ void intel_mode_from_pipe_config(struct drm_display_mode *mode,
> > > struct intel_crtc_state *pipe_config);
> > >
> > > int skl_update_scaler_crtc(struct intel_crtc_state *crtc_state);
> > > +int skl_update_scaler_crtc_hdmi_output(struct intel_crtc_state *state);
> > > int skl_max_scale(struct intel_crtc *crtc, struct intel_crtc_state *crtc_state);
> > >
> > > static inline u32 intel_plane_ggtt_offset(const struct intel_plane_state *state)
> > > diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> > > index 22da5cd..8d5aa1e 100644
> > > --- a/drivers/gpu/drm/i915/intel_hdmi.c
> > > +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> > > @@ -1415,6 +1415,7 @@ intel_hdmi_compute_ycbcr_config(struct drm_connector_state *conn_state,
> > > }
> > >
> > > if (type == DRM_HDMI_OUTPUT_YCBCR420) {
> > > + struct intel_crtc *intel_crtc = to_intel_crtc(conn_state->crtc);
> > >
> > > /* YCBCR420 TMDS rate requirement is half the pixel clock */
> > > config->hdmi_output = DRM_HDMI_OUTPUT_YCBCR420;
> > > @@ -1422,6 +1423,15 @@ intel_hdmi_compute_ycbcr_config(struct drm_connector_state *conn_state,
> > > *clock_12bpc /= 2;
> > > *clock_8bpc /= 2;
> > >
> > > + /* YCBCR 420 output conversion needs a scaler */
> > > + if (skl_update_scaler_crtc_hdmi_output(config)) {
> > > + DRM_ERROR("Scaler allocation for output failed\n");
> > > + return DRM_HDMI_OUTPUT_INVALID;
> > > + }
> > > +
> > > + /* Bind this scaler to pipe */
> > > + intel_pch_panel_fitting(intel_crtc, config,
> > > + DRM_MODE_SCALE_FULLSCREEN);
> > > }
> > >
> > > /* Encoder is capable of this output, lets commit to CRTC */
> > > diff --git a/drivers/gpu/drm/i915/intel_panel.c b/drivers/gpu/drm/i915/intel_panel.c
> > > index 96c2cbd..b6a32c4 100644
> > > --- a/drivers/gpu/drm/i915/intel_panel.c
> > > +++ b/drivers/gpu/drm/i915/intel_panel.c
> > > @@ -110,7 +110,8 @@ intel_pch_panel_fitting(struct intel_crtc *intel_crtc,
> > >
> > > /* Native modes don't need fitting */
> > > if (adjusted_mode->crtc_hdisplay == pipe_config->pipe_src_w &&
> > > - adjusted_mode->crtc_vdisplay == pipe_config->pipe_src_h)
> > > + adjusted_mode->crtc_vdisplay == pipe_config->pipe_src_h &&
> > > + pipe_config->hdmi_output != DRM_HDMI_OUTPUT_YCBCR420)
> >
> > I don't like that the knowledge that YCBCR420 needs the scaler is spread
> > everywhere, including this function that should only deal with panel fitting. I
> > would rather add a force parameter to intel_pch_panel_fitting() and
> > skl_update_scaler() that would mean setup the scaler even if looks like it's not
> > necessary. That way the hdmi code would just call them with force enabled,
> > without sprinkling "hdmi_output == YCBCR420" everywhere.
>
> As explained in the comment above, its special case usage of pipe
> scalar, and that's why being checked specifically.
I'm still not convinced about this. If this is a special scaler mode that is not
panel fitting, then this should definitely not touch a function in
intel_panel.c, specially one with "panel fitting" in the name.
My point is, if this is panel fitting, then it should use panel fitting code
without special casing. If it isn't, then it should have its own code paths. But
this patch just creates a blurry line where the panel fitting code needs to be
special cased for when the HDMI output is YCBCR420 and we are *not* actually
doing panel fitting.
Ander
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