Re: [PATCH RFC v2 3/8] drm/bridge: synopsys: dw-hdmi: add bus format negociation

[Neil Armstrong <narmstrong@baylibre.com>]

On 27/08/2019 11:03, Boris Brezillon wrote:
> On Tue, 27 Aug 2019 10:14:20 +0200
> Neil Armstrong <narmstrong@baylibre.com> wrote:
> 
>> Add the atomic_get_output_bus_fmts, atomic_get_input_bus_fmts to negociate
> 
> 								   ^negotiate
> 
>> the possible output and input formats for the current mode and monitor,
>> and use the negociated formats in a basic atomic_check callback.
> 
> 	      ^negotiated

Indeed, thx

> 
>>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> ---
> 
> 
>>  
>> +static void dw_hdmi_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
>> +					struct drm_bridge_state *bridge_state,
>> +					struct drm_crtc_state *crtc_state,
>> +					struct drm_connector_state *conn_state,
>> +					unsigned int *num_output_fmts,
>> +					u32 *output_fmts)
>> +{
>> +	struct drm_connector *conn = conn_state->connector;
>> +	struct drm_display_info *info = &conn->display_info;
>> +	struct drm_display_mode *mode = &crtc_state->mode;
>> +	bool is_hdmi2_sink = info->hdmi.scdc.supported;	
>> +	int i = 0;
>> +
>> +	/*
>> +	 * If the current mode enforces 4:2:0, force the output but format
>> +	 * to 4:2:0 and do not add the YUV422/444/RGB formats
>> +	 */
>> +	if (drm_mode_is_420_only(info, mode) ||
>> +	    (!is_hdmi2_sink && drm_mode_is_420_also(info, mode))) {
>> +
>> +		/* Order bus formats from 16bit to 8bit if supported */
>> +		if (info->bpc == 16 &&
>> +		    (info->hdmi.y420_dc_modes & DRM_EDID_YCBCR420_DC_48)) {
>> +			if (output_fmts)
>> +				output_fmts[i] = MEDIA_BUS_FMT_UYYVYY16_0_5X48;
>> +			++i;
>> +		}
> 
> You could probably add the following helper:
> 
> static void dw_hdmi_bridge_add_fmt(unsigned int *num_fmts, u32 *fmts,
> 				   u32 new_fmt)
> {
> 	if (fmts)
> 		fmts[*num_fmts] = new_fmt;
> 
> 	(*num_fmts)++;
> }
> 
> to avoid duplicating the
> 
> 	if (fmts)
> 		...
> 
> 	i++;			
> 
> logic.
> 

Yes, I was planning this,

Thanks,
Neil


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