[PATCH 02/16] drm/i915/display: Prepare for dsc 3 stream splitter

Nautiyal, Ankit K ankit.k.nautiyal at intel.com
Tue Oct 22 03:53:12 UTC 2024


On 10/21/2024 6:16 PM, Jani Nikula wrote:
> On Mon, 21 Oct 2024, Ankit Nautiyal <ankit.k.nautiyal at intel.com> wrote:
>> At the moment dsc_split represents that dsc splitter is used or not.
>> With 3 DSC engines, the splitter can split into two streams or three
>> streams. Make the member dsc_split as int and set that to 2 when dsc
>> splitter splits to 2 stream.
> Maybe also name it accordingly? "dsc split" sounds like a boolean, not
> like an int.
>
> Moreover, when you change the meaning of a member, it's often good code
> hygiene to rename the member to catch any incorrect uses and to ensure
> you changed them all.

Noted. Will change the name accordingly.

>
>> v2: Avoid new enum for dsc split. (Suraj)
>>
>> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
>> ---
>>   drivers/gpu/drm/i915/display/icl_dsi.c        |  2 +-
>>   drivers/gpu/drm/i915/display/intel_display.c  |  2 +-
>>   .../drm/i915/display/intel_display_types.h    |  2 +-
>>   drivers/gpu/drm/i915/display/intel_dp.c       |  2 +-
>>   drivers/gpu/drm/i915/display/intel_vdsc.c     | 20 ++++++++++++++-----
>>   5 files changed, 19 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/icl_dsi.c b/drivers/gpu/drm/i915/display/icl_dsi.c
>> index 87a27d91d15d..553e75cf118c 100644
>> --- a/drivers/gpu/drm/i915/display/icl_dsi.c
>> +++ b/drivers/gpu/drm/i915/display/icl_dsi.c
>> @@ -1595,7 +1595,7 @@ static int gen11_dsi_dsc_compute_config(struct intel_encoder *encoder,
>>   
>>   	/* FIXME: split only when necessary */
>>   	if (crtc_state->dsc.slice_count > 1)
>> -		crtc_state->dsc.dsc_split = true;
>> +		crtc_state->dsc.dsc_split = 2;
>>   
>>   	/* FIXME: initialize from VBT */
>>   	vdsc_cfg->rc_model_size = DSC_RC_MODEL_SIZE_CONST;
>> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
>> index ef1436146325..9e2f0fd0558f 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display.c
>> +++ b/drivers/gpu/drm/i915/display/intel_display.c
>> @@ -5741,7 +5741,7 @@ intel_pipe_config_compare(const struct intel_crtc_state *current_config,
>>   	PIPE_CONF_CHECK_I(dsc.config.nsl_bpg_offset);
>>   
>>   	PIPE_CONF_CHECK_BOOL(dsc.compression_enable);
>> -	PIPE_CONF_CHECK_BOOL(dsc.dsc_split);
>> +	PIPE_CONF_CHECK_I(dsc.dsc_split);
>>   	PIPE_CONF_CHECK_I(dsc.compressed_bpp_x16);
>>   
>>   	PIPE_CONF_CHECK_BOOL(splitter.enable);
>> diff --git a/drivers/gpu/drm/i915/display/intel_display_types.h b/drivers/gpu/drm/i915/display/intel_display_types.h
>> index 2bb1fa64da2f..58f510909f4d 100644
>> --- a/drivers/gpu/drm/i915/display/intel_display_types.h
>> +++ b/drivers/gpu/drm/i915/display/intel_display_types.h
>> @@ -1235,7 +1235,7 @@ struct intel_crtc_state {
>>   	/* Display Stream compression state */
>>   	struct {
>>   		bool compression_enable;
>> -		bool dsc_split;
>> +		int dsc_split;
>>   		/* Compressed Bpp in U6.4 format (first 4 bits for fractional part) */
>>   		u16 compressed_bpp_x16;
>>   		u8 slice_count;
>> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
>> index 286b272aa98c..c1867c883b73 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dp.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
>> @@ -2409,7 +2409,7 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
>>   	 * then we need to use 2 VDSC instances.
>>   	 */
>>   	if (pipe_config->joiner_pipes || pipe_config->dsc.slice_count > 1)
>> -		pipe_config->dsc.dsc_split = true;
>> +		pipe_config->dsc.dsc_split = 2;
>>   
>>   	ret = intel_dp_dsc_compute_params(connector, pipe_config);
>>   	if (ret < 0) {
>> diff --git a/drivers/gpu/drm/i915/display/intel_vdsc.c b/drivers/gpu/drm/i915/display/intel_vdsc.c
>> index 40525f5c4c42..3bce13c21756 100644
>> --- a/drivers/gpu/drm/i915/display/intel_vdsc.c
>> +++ b/drivers/gpu/drm/i915/display/intel_vdsc.c
>> @@ -379,7 +379,14 @@ intel_dsc_power_domain(struct intel_crtc *crtc, enum transcoder cpu_transcoder)
>>   
>>   static int intel_dsc_get_vdsc_per_pipe(const struct intel_crtc_state *crtc_state)
>>   {
>> -	return crtc_state->dsc.dsc_split ? 2 : 1;
>> +	switch (crtc_state->dsc.dsc_split) {
>> +	case 2:
>> +		return 2;
>> +	case 0:
>> +	default:
>> +		break;
>> +	}
>> +	return 1;
> Seems overly complicated.
>
>>   }
>>   
>>   int intel_dsc_get_num_vdsc_instances(const struct intel_crtc_state *crtc_state)
>> @@ -976,8 +983,11 @@ void intel_dsc_get_config(struct intel_crtc_state *crtc_state)
>>   	if (!crtc_state->dsc.compression_enable)
>>   		goto out;
>>   
>> -	crtc_state->dsc.dsc_split = (dss_ctl2 & RIGHT_BRANCH_VDSC_ENABLE) &&
>> -		(dss_ctl1 & JOINER_ENABLE);
>> +	if ((dss_ctl1 & JOINER_ENABLE) &&
>> +	    (dss_ctl2 & RIGHT_BRANCH_VDSC_ENABLE))
> The extra parens are unnecessary.
>
>> +		crtc_state->dsc.dsc_split = 2;
>> +	else
>> +		crtc_state->dsc.dsc_split = 0;
>>   
>>   	intel_dsc_get_pps_config(crtc_state);
>>   out:
>> @@ -988,10 +998,10 @@ static void intel_vdsc_dump_state(struct drm_printer *p, int indent,
>>   				  const struct intel_crtc_state *crtc_state)
>>   {
>>   	drm_printf_indent(p, indent,
>> -			  "dsc-dss: compressed-bpp:" FXP_Q4_FMT ", slice-count: %d, split: %s\n",
>> +			  "dsc-dss: compressed-bpp:" FXP_Q4_FMT ", slice-count: %d, split: %d\n",
> So what does the reader think when they see "split: 1" in the logs?
> Split enabled?

I was meaning to capture the DSC split state as originally intended, and 
extend it to have splitting to 3, 2, or None.

With that we can never have split: 1, but can have either 3, 2, or 0.

I realize, split:0 is a bit ambiguous, so I am thinking about:

-change the dsc_split to dsc_streams: to capture number of DSC streams 
per pipe, instead of DSC splitter operation.

-dsc_streams can be 1, 2 and extended to 3.

-Splitter state will then be implicit, 1 DSC Stream => No Splitter, 2 
DSC Streams => Splitter used to split 2 DSC streams and so on.

With that, deriving number of DSC engine will also be straight forward 
(avoiding the switch case above).


Thanks & Regards,

Ankit



>
>>   			  FXP_Q4_ARGS(crtc_state->dsc.compressed_bpp_x16),
>>   			  crtc_state->dsc.slice_count,
>> -			  str_yes_no(crtc_state->dsc.dsc_split));
>> +			  crtc_state->dsc.dsc_split);
>>   }
>>   
>>   void intel_vdsc_state_dump(struct drm_printer *p, int indent,


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