Re: [PATCH v3 7/7] drm/i915: Add YCBCR 4:2:0/4:4:4 support for LSPCON

Sharma, Shashank
2018-01-18T15:30:53Z

Regards

Shashank

On 1/18/2018 7:33 PM, Ville Syrjälä wrote:
> On Thu, Jan 18, 2018 at 11:57:09AM +0530, Sharma, Shashank wrote:
>> Regards
>>
>> Shashank
>>
>>
>> On 1/17/2018 11:57 PM, Ville Syrjälä wrote:
>>> On Fri, Jan 05, 2018 at 03:15:35PM +0530, Shashank Sharma wrote:
>>>> 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)
>>>>
>>>> Cc: Ville Syrjala <ville.syrjala@linux.intel.com>
>>>> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>>>> Signed-off-by: Shashank Sharma <shashank.sharma@intel.com>
>>>> ---
>>>> drivers/gpu/drm/i915/i915_reg.h | 2 ++
>>>> drivers/gpu/drm/i915/intel_ddi.c | 7 +++++++
>>>> drivers/gpu/drm/i915/intel_dp.c | 10 ++++++++++
>>>> drivers/gpu/drm/i915/intel_drv.h | 2 ++
>>>> drivers/gpu/drm/i915/intel_lspcon.c | 28 ++++++++++++++++++++++++++++
>>>> 5 files changed, 49 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
>>>> index 966e4df..45ee264 100644
>>>> --- a/drivers/gpu/drm/i915/i915_reg.h
>>>> +++ b/drivers/gpu/drm/i915/i915_reg.h
>>>> @@ -8547,6 +8547,8 @@ 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 7b89f2a..7616f6f 100644
>>>> --- a/drivers/gpu/drm/i915/intel_ddi.c
>>>> +++ b/drivers/gpu/drm/i915/intel_ddi.c
>>>> @@ -1499,6 +1499,13 @@ 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.
>>>> + */
>>>> + if (crtc_state->output_format == CRTC_OUTPUT_YCBCR444)
>>>> + temp |= TRANS_MSA_SAMPLING_444 | TRANS_MSA_CLRSP_YCBCR;
>>> This fails to state that we're indicating BT.601 encoding. I think we
>>> should spell that out explicitly.
>> Agree, I will add this in comments.
>>>> I915_WRITE(TRANS_MSA_MISC(cpu_transcoder), temp);
>>>> }
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
>>>> index 35c5299..3bf82ea 100644
>>>> --- a/drivers/gpu/drm/i915/intel_dp.c
>>>> +++ b/drivers/gpu/drm/i915/intel_dp.c
>>>> @@ -1613,6 +1613,7 @@ 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;
>>>> @@ -1642,6 +1643,15 @@ intel_dp_compute_config(struct intel_encoder *encoder,
>>>> if (HAS_PCH_SPLIT(dev_priv) && !HAS_DDI(dev_priv) && port != PORT_A)
>>>> pipe_config->has_pch_encoder = true;
>>>>
>>>> + if (lspcon->active) {
>>>> + struct drm_connector *connector = &intel_connector->base;
>>>> +
>>>> + if (lspcon_ycbcr420_config(connector, pipe_config)) {
>>>> + pipe_config->output_format = CRTC_OUTPUT_YCBCR444;
>>> I think I'd like to see all compute_config hooks explicitly set the
>>> outout_format (to RGB usually obviously).
>> That's the one I was talking about in previous patch. If we keep
>> output_format_RGB = 0, we need
>> not to do this, as reset of the pipe_config will automatically make it RGB.
> IMO either we have INVALID=0 so that we use it to catch readout
> fails, or we have no INVALID. Other options make little sense to me.
Its a minor thing, and doesn't really matter. I can change this.
>>>> + lspcon->output_format = CRTC_OUTPUT_YCBCR420;
>>> You should not modify any non-atomic state like that in compute_config.
>> Please help me to understand this better, Can you elaborate a bit more on:
>> - Why is this a non-atomic state ?
>> - What is the right place we should modify it ?
> I don't think you need it at all. Just consult the crtc state when
> needed.
I dont think CRTC state can cover all the cases, for example, what would
be do when we need
YCBCR 4:4:4 output from LSPCON ? As we have already used crtc_state->444
for LSPCON output
420, we can't handle this. This is equivalent to your previous
suggestion of adding 'scaling_reqd',
but I added in LPSCON (instead of CRTC state) as this information is
required only in case of LSPCON.
In all native cases, scaling would be always required for 4:2:0 outputs.

- Shashank
>> - Shashank
>>>> + }
>>>> + }
>>>> +
>>>> 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 2de6b41..5edba06 100644
>>>> --- a/drivers/gpu/drm/i915/intel_drv.h
>>>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>>>> @@ -2047,6 +2047,8 @@ void lspcon_set_infoframes(struct drm_encoder *encoder,
>>>> const struct drm_connector_state *conn_state);
>>>> bool lspcon_infoframe_enabled(struct drm_encoder *encoder,
>>>> const struct intel_crtc_state *pipe_config);
>>>> +bool lspcon_ycbcr420_config(struct drm_connector *connector,
>>>> + struct intel_crtc_state *config);
>>>>
>>>> /* intel_pipe_crc.c */
>>>> int intel_pipe_crc_create(struct drm_minor *minor);
>>>> diff --git a/drivers/gpu/drm/i915/intel_lspcon.c b/drivers/gpu/drm/i915/intel_lspcon.c
>>>> index 066ea91..cb88138 100644
>>>> --- a/drivers/gpu/drm/i915/intel_lspcon.c
>>>> +++ b/drivers/gpu/drm/i915/intel_lspcon.c
>>>> @@ -180,6 +180,25 @@ static bool lspcon_wake_native_aux_ch(struct intel_lspcon *lspcon)
>>>> return true;
>>>> }
>>>>
>>>> +bool lspcon_ycbcr420_config(struct drm_connector *connector,
>>>> + struct intel_crtc_state *config)
>>>> +{
>>>> + struct drm_display_info *info = &connector->display_info;
>>>> + struct drm_display_mode *mode = &config->base.adjusted_mode;
>>>> +
>>>> + if (drm_mode_is_420_only(info, mode)) {
>>>> + if (!connector->ycbcr_420_allowed) {
>>>> + DRM_ERROR("Platform doesn't support YCBCR420 output\n");
>>>> + return false;
>>>> + }
>>>> +
>>>> + config->port_clock /= 2;
>>>> + return true;
>>>> + }
>>>> +
>>>> + return false;
>>>> +}
>>>> +
>>>> static bool lspcon_probe(struct intel_lspcon *lspcon)
>>>> {
>>>> int retry;
>>>> @@ -459,6 +478,13 @@ void lspcon_set_infoframes(struct drm_encoder *encoder,
>>>> return;
>>>> }
>>>>
>>>> + if (lspcon->output_format == CRTC_OUTPUT_YCBCR420)
>>>> + frame.avi.colorspace = HDMI_COLORSPACE_YUV420;
>>>> + else if (lspcon->output_format == CRTC_OUTPUT_YCBCR444)
>>>> + 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 :
>>>> @@ -512,6 +538,7 @@ 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");
>>>> @@ -536,6 +563,7 @@ 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