On Sat, Oct 13, 2018 at 12:02:25AM +0530, Sharma, Shashank wrote:
> Regards
> 
> Shashank
> 
> 
> On 10/12/2018 11:39 PM, Ville Syrjälä wrote:
> > On Fri, Oct 12, 2018 at 11:21:56PM +0530, Sharma, Shashank wrote:
> >> Regards
> >>
> >> Shashank
> >>
> >>
> >> On 10/12/2018 7:28 PM, Ville Syrjälä wrote:
> >>> On Fri, Oct 12, 2018 at 11:53:14AM +0530, Shashank Sharma wrote:
> >>>> From: Shashank Sharma <[email protected]>
> >>>>
> >>>> LSPCON chips can generate YCBCR outputs, if asked nicely :).
> >>>>
> >>>> In order to generate YCBCR 4:2:0 outputs, a source must:
> >>>> - send YCBCR 4:4:4 signals to LSPCON
> >>>> - program color space as 4:2:0 in AVI infoframes
> >>>>
> >>>> Whereas for YCBCR 4:4:4 outputs, the source must:
> >>>> - send YCBCR 4:4:4 signals to LSPCON
> >>>> - program color space as 4:4:4 in AVI infoframes
> >>>>
> >>>> So for both 4:2:0 as well as 4:4:4 outputs, we are driving the
> >>>> pipe for YCBCR 4:4:4 output, but AVI infoframe's color space
> >>>> information indicates LSPCON FW to start scaling down from YCBCR
> >>>> 4:4:4 and generate YCBCR 4:2:0 output. As the scaling is done by
> >>>> LSPCON device, we need not to reserve a scaler for 4:2:0 outputs.
> >>>>
> >>>> V2: rebase
> >>>> V3: Addressed review comments from Ville
> >>>>       - add enum crtc_output_format instead of bool ycbcr420
> >>>>       - use crtc_output_format=4:4:4 for modeset of LSPCON 4:2:0 output
> >>>>         cases in this way we will have YCBCR 4:4:4 framework ready 
> >>>> (except
> >>>>         the ABI part)
> >>>> V4: Added r-b from Maarten (for v3)
> >>>>       Addressed review comments from Ville:
> >>>>       - Do not add a non-atomic state variable to determine lspcon 
> >>>> output.
> >>>>         Instead add bool in CRTC state to indicate lspcon based scaling.
> >>>> V5: Addressed review comments from Ville:
> >>>>       - Change the state bool name from external scaling to something 
> >>>> more
> >>>>         relavent.
> >>>>       - Keep the info and adjusted_mode structures const.
> >>>>       - use crtc_state instead of pipe_config.
> >>>>       - Push all the config change into lspcon_ycbcr420_config function.
> >>>> V6: Rebase, small changes to accommodate changes in patch 2.
> >>>> V7: Fixed checkpatch warnings for alignment
> >>>> V8: Rebase
> >>>>
> >>>>       PS: Ignored following warnings to match the current formatting:
> >>>>       drm/i915: Add YCBCR 4:2:0/4:4:4 support for LSPCON
> >>>>        -:53: CHECK:SPACING: spaces preferred around that '<<' (ctx:VxV)
> >>>>       #53: FILE: drivers/gpu/drm/i915/i915_reg.h:8721:
> >>>>       +#define  TRANS_MSA_SAMPLING_444        (2<<1)
> >>>>                                             ^
> >>>>       -:54: CHECK:SPACING: spaces preferred around that '<<' (ctx:VxV)
> >>>>       #54: FILE: drivers/gpu/drm/i915/i915_reg.h:8722:
> >>>>       +#define  TRANS_MSA_CLRSP_YCBCR         (2<<3)
> >>>> V9: Rebase
> >>>> V10: Rebase
> >>>> V11: Rebase
> >>>>
> >>>> Cc: Ville Syrjala <[email protected]>
> >>>> Cc: Maarten Lankhorst <[email protected]>
> >>>> Reviewed-by: Maarten Lankhorst <[email protected]>
> >>>> Signed-off-by: Shashank Sharma <[email protected]>
> >>>> ---
> >>>>    drivers/gpu/drm/i915/i915_reg.h      |  2 ++
> >>>>    drivers/gpu/drm/i915/intel_ddi.c     |  7 +++++++
> >>>>    drivers/gpu/drm/i915/intel_display.c | 12 ++++++++++++
> >>>>    drivers/gpu/drm/i915/intel_dp.c      |  4 ++++
> >>>>    drivers/gpu/drm/i915/intel_drv.h     |  5 +++++
> >>>>    drivers/gpu/drm/i915/intel_lspcon.c  | 26 ++++++++++++++++++++++++++
> >>>>    6 files changed, 56 insertions(+)
> >>>>
> >>>> diff --git a/drivers/gpu/drm/i915/i915_reg.h 
> >>>> b/drivers/gpu/drm/i915/i915_reg.h
> >>>> index 2078541..1e13e51 100644
> >>>> --- a/drivers/gpu/drm/i915/i915_reg.h
> >>>> +++ b/drivers/gpu/drm/i915/i915_reg.h
> >>>> @@ -9229,6 +9229,8 @@ enum skl_power_gate {
> >>>>    #define TRANS_MSA_MISC(tran) _MMIO_TRANS2(tran, _TRANSA_MSA_MISC)
> >>>>    
> >>>>    #define  TRANS_MSA_SYNC_CLK           (1 << 0)
> >>>> +#define  TRANS_MSA_SAMPLING_444         (2 << 1)
> >>>> +#define  TRANS_MSA_CLRSP_YCBCR          (2 << 3)
> >>>>    #define  TRANS_MSA_6_BPC              (0 << 5)
> >>>>    #define  TRANS_MSA_8_BPC              (1 << 5)
> >>>>    #define  TRANS_MSA_10_BPC             (2 << 5)
> >>>> diff --git a/drivers/gpu/drm/i915/intel_ddi.c 
> >>>> b/drivers/gpu/drm/i915/intel_ddi.c
> >>>> index be21131..186111a 100644
> >>>> --- a/drivers/gpu/drm/i915/intel_ddi.c
> >>>> +++ b/drivers/gpu/drm/i915/intel_ddi.c
> >>>> @@ -1784,6 +1784,13 @@ void intel_ddi_set_pipe_settings(const struct 
> >>>> intel_crtc_state *crtc_state)
> >>>>                  break;
> >>>>          }
> >>>>    
> >>>> +        /*
> >>>> +         * As per DP 1.2 spec section 2.3.4.3 while sending
> >>>> +         * YCBCR 444 signals we should program MSA MISC1/0 fields with
> >>>> +         * colorspace information. The output colorspace encoding is 
> >>>> BT601.
> >>>> +         */
> >>>> +        if (crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR444)
> >>>> +                temp |= TRANS_MSA_SAMPLING_444 | TRANS_MSA_CLRSP_YCBCR;
> >>>>          I915_WRITE(TRANS_MSA_MISC(cpu_transcoder), temp);
> >>>>    }
> >>>>    
> >>>> diff --git a/drivers/gpu/drm/i915/intel_display.c 
> >>>> b/drivers/gpu/drm/i915/intel_display.c
> >>>> index 3317c6c..41abd03 100644
> >>>> --- a/drivers/gpu/drm/i915/intel_display.c
> >>>> +++ b/drivers/gpu/drm/i915/intel_display.c
> >>>> @@ -7797,6 +7797,8 @@ static void intel_get_crtc_ycbcr_config(struct 
> >>>> intel_crtc *crtc,
> >>>>          struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> >>>>          enum intel_output_format output = INTEL_OUTPUT_FORMAT_RGB;
> >>>>    
> >>>> +        pipe_config->lspcon_downsampling = false;
> >>>> +
> >>>>          if (IS_BROADWELL(dev_priv) || INTEL_GEN(dev_priv) >= 9) {
> >>>>                  u32 tmp = I915_READ(PIPEMISC(crtc->pipe));
> >>>>    
> >>>> @@ -7814,6 +7816,16 @@ static void intel_get_crtc_ycbcr_config(struct 
> >>>> intel_crtc *crtc,
> >>>>                                  else
> >>>>                                          output = 
> >>>> INTEL_OUTPUT_FORMAT_YCBCR420;
> >>>>                          } else {
> >>>> +                                /*
> >>>> +                                 * Currently there is no interface 
> >>>> defined to
> >>>> +                                 * check user preference between 
> >>>> RGB/YCBCR444
> >>>> +                                 * or YCBCR420. So the only possible 
> >>>> case for
> >>>> +                                 * YCBCR444 usage is driving YCBCR420 
> >>>> output
> >>>> +                                 * with LSPCON, when pipe is configured 
> >>>> for
> >>>> +                                 * YCBCR444 output and LSPCON takes 
> >>>> care of
> >>>> +                                 * downsampling it.
> >>>> +                                 */
> >>>> +                                pipe_config->lspcon_downsampling = true;
> >>>>                                  output = INTEL_OUTPUT_FORMAT_YCBCR444;
> >>>>                          }
> >>>>                  }
> >>>> diff --git a/drivers/gpu/drm/i915/intel_dp.c 
> >>>> b/drivers/gpu/drm/i915/intel_dp.c
> >>>> index c3f6330..1156d59 100644
> >>>> --- a/drivers/gpu/drm/i915/intel_dp.c
> >>>> +++ b/drivers/gpu/drm/i915/intel_dp.c
> >>>> @@ -2074,6 +2074,7 @@ intel_dp_compute_config(struct intel_encoder 
> >>>> *encoder,
> >>>>          struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
> >>>>          struct drm_display_mode *adjusted_mode = 
> >>>> &pipe_config->base.adjusted_mode;
> >>>>          struct intel_dp *intel_dp = enc_to_intel_dp(&encoder->base);
> >>>> +        struct intel_lspcon *lspcon = 
> >>>> enc_to_intel_lspcon(&encoder->base);
> >>>>          enum port port = encoder->port;
> >>>>          struct intel_crtc *intel_crtc = 
> >>>> to_intel_crtc(pipe_config->base.crtc);
> >>>>          struct intel_connector *intel_connector = 
> >>>> intel_dp->attached_connector;
> >>>> @@ -2086,6 +2087,9 @@ intel_dp_compute_config(struct intel_encoder 
> >>>> *encoder,
> >>>>                  pipe_config->has_pch_encoder = true;
> >>>>    
> >>>>          pipe_config->output_format = INTEL_OUTPUT_FORMAT_RGB;
> >>>> +        if (lspcon->active)
> >>>> +                lspcon_ycbcr420_config(&intel_connector->base, 
> >>>> pipe_config);
> >>>> +
> >>>>          pipe_config->has_drrs = false;
> >>>>          if (IS_G4X(dev_priv) || port == PORT_A)
> >>>>                  pipe_config->has_audio = false;
> >>>> diff --git a/drivers/gpu/drm/i915/intel_drv.h 
> >>>> b/drivers/gpu/drm/i915/intel_drv.h
> >>>> index b8e5f95..95e252e 100644
> >>>> --- a/drivers/gpu/drm/i915/intel_drv.h
> >>>> +++ b/drivers/gpu/drm/i915/intel_drv.h
> >>>> @@ -908,6 +908,9 @@ struct intel_crtc_state {
> >>>>    
> >>>>          /* Output format RGB/YCBCR etc */
> >>>>          enum intel_output_format output_format;
> >>>> +
> >>>> +        /* Output down scaling is done in LSPCON device */
> >>>> +        bool lspcon_downsampling;
> >>>>    };
> >>>>    
> >>>>    struct intel_crtc {
> >>>> @@ -2225,6 +2228,8 @@ void lspcon_set_infoframes(struct intel_encoder 
> >>>> *encoder,
> >>>>                             const struct drm_connector_state 
> >>>> *conn_state);
> >>>>    bool lspcon_infoframe_enabled(struct intel_encoder *encoder,
> >>>>                                const struct intel_crtc_state 
> >>>> *pipe_config);
> >>>> +void lspcon_ycbcr420_config(struct drm_connector *connector,
> >>>> +                            struct intel_crtc_state *crtc_state);
> >>>>    
> >>>>    /* intel_pipe_crc.c */
> >>>>    #ifdef CONFIG_DEBUG_FS
> >>>> diff --git a/drivers/gpu/drm/i915/intel_lspcon.c 
> >>>> b/drivers/gpu/drm/i915/intel_lspcon.c
> >>>> index 829c40a..fff32b3 100644
> >>>> --- a/drivers/gpu/drm/i915/intel_lspcon.c
> >>>> +++ b/drivers/gpu/drm/i915/intel_lspcon.c
> >>>> @@ -180,6 +180,21 @@ static bool lspcon_wake_native_aux_ch(struct 
> >>>> intel_lspcon *lspcon)
> >>>>          return true;
> >>>>    }
> >>>>    
> >>>> +void lspcon_ycbcr420_config(struct drm_connector *connector,
> >>>> +                            struct intel_crtc_state *crtc_state)
> >>>> +{
> >>>> +        const struct drm_display_info *info = &connector->display_info;
> >>>> +        const struct drm_display_mode *adjusted_mode =
> >>>> +                                        &crtc_state->base.adjusted_mode;
> >>>> +
> >>>> +        if (drm_mode_is_420_only(info, adjusted_mode) &&
> >>>> +            connector->ycbcr_420_allowed) {
> >>>> +                crtc_state->port_clock /= 2;
> >>> This looks bogus. We're talking about DP here so we should not be
> >>> frobbing port_clock. And since we output 4:4:4 from the port
> >>> anyway we don't even have to take 4:2:0 into consideration
> >>> when calculating port_clock.
> >> I agree on this.
> >>> Ah, this guy is called before we even calculate port_clock.
> >>> That explains why this didn't cause any problems. So this is
> >>> just dead code here.
> >>>
> >>> And looks like the port_clock adjustment in intel_hdmi_ycbcr420_config()
> >>> also dead code since the caller overwrites it there as well.
> >> I am not sure if that's the case for Native HDMI 2.0.
> >> In intel_hdmi_420_config we are updating the config->port_clock, which
> >> is the same thing being updated for 8/12/16 BPC deep color too, just
> >> after this function.
> >> I have tested the output with HDMI 2.0 analyzer, which reported right
> >> pixel clock (297Mhz). Now, as any of the port clock calculations do not
> >> get information
> >> about HDMI output type, there is no other way they will calculate the
> >> right pixel clock (594/2) for 4:2:0 outputs. So I believe that code is
> >> active.
> > It effectively does this:
> >
> > 1. port_clock = who knows
> > 2. port_clock /= 2;
> Here, in intel_hdmi_compute_ycbcr_config() function, we are additionally 
> doing this also:
> 
> clock_8bpc /= 2;
> clock_10bpc /= 2;
> clock_12bpc /= 2;
> 
> > 3. if (12bpc)
> >             port_clock = clock_12bpc;
> >     else if (10bpc)
> >             port_clock = clock_10bpc;
> >     else
> >             port_clock = clock_8bpc;
> This means effectively the selected clock is /2, so the code is not dead 
> (thankfully :-))

Only the port_clock/=2 part. I never claimed the rest was dead.

> - Shashank
> >
> > Ie. step 2. is dead code.
> >
> >> - Shashank
> >>>> +                crtc_state->output_format = 
> >>>> INTEL_OUTPUT_FORMAT_YCBCR444;
> >>>> +                crtc_state->lspcon_downsampling = true;
> >>>> +        }
> >>>> +}
> >>>> +
> >>>>    static bool lspcon_probe(struct intel_lspcon *lspcon)
> >>>>    {
> >>>>          int retry;
> >>>> @@ -464,6 +479,15 @@ void lspcon_set_infoframes(struct intel_encoder 
> >>>> *encoder,
> >>>>                  return;
> >>>>          }
> >>>>    
> >>>> +        if (crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR444) {
> >>>> +                if (crtc_state->lspcon_downsampling)
> >>>> +                        frame.avi.colorspace = HDMI_COLORSPACE_YUV420;
> >>>> +                else
> >>>> +                        frame.avi.colorspace = HDMI_COLORSPACE_YUV444;
> >>>> +        } else {
> >>>> +                frame.avi.colorspace = HDMI_COLORSPACE_RGB;
> >>>> +        }
> >>>> +
> >>>>          drm_hdmi_avi_infoframe_quant_range(&frame.avi, mode,
> >>>>                                             
> >>>> crtc_state->limited_color_range ?
> >>>>                                             
> >>>> HDMI_QUANTIZATION_RANGE_LIMITED :
> >>>> @@ -517,6 +541,7 @@ bool lspcon_init(struct intel_digital_port 
> >>>> *intel_dig_port)
> >>>>          struct intel_lspcon *lspcon = &intel_dig_port->lspcon;
> >>>>          struct drm_device *dev = intel_dig_port->base.base.dev;
> >>>>          struct drm_i915_private *dev_priv = to_i915(dev);
> >>>> +        struct drm_connector *connector = &dp->attached_connector->base;
> >>>>    
> >>>>          if (!HAS_LSPCON(dev_priv)) {
> >>>>                  DRM_ERROR("LSPCON is not supported on this platform\n");
> >>>> @@ -541,6 +566,7 @@ bool lspcon_init(struct intel_digital_port 
> >>>> *intel_dig_port)
> >>>>                  return false;
> >>>>          }
> >>>>    
> >>>> +        connector->ycbcr_420_allowed = true;
> >>>>          lspcon->active = true;
> >>>>          DRM_DEBUG_KMS("Success: LSPCON init\n");
> >>>>          return true;
> >>>> -- 
> >>>> 2.7.4

-- 
Ville Syrjälä
Intel
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