Message-ID: <2970638.5fSG56mABF@jernej-laptop>
Date:   Sat, 29 Feb 2020 12:07:17 +0100
From:   Jernej Škrabec <jernej.skrabec@...l.net>
To:     a.hajda@...sung.com, Laurent.pinchart@...asonboard.com,
        boris.brezillon@...labora.com,
        Neil Armstrong <narmstrong@...libre.com>,
        Jonas Karlman <jonas@...boo.se>
Cc:     linux-amlogic@...ts.infradead.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 04/11] drm/bridge: synopsys: dw-hdmi: add bus format negociation

Dne sobota, 29. februar 2020 ob 11:09:14 CET je Jonas Karlman napisal(a):
> Hi Jernej,
> 
> On 2020-02-29 08:42, Jernej Škrabec wrote:
> > Hi Neil!
> > 
> > Dne četrtek, 06. februar 2020 ob 20:18:27 CET je Neil Armstrong 
napisal(a):
> >> Add the atomic_get_output_bus_fmts, atomic_get_input_bus_fmts to
> >> negociate
> >> the possible output and input formats for the current mode and monitor,
> >> and use the negotiated formats in a basic atomic_check callback.
> >> 
> >> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
> >> ---
> >> 
> >>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 272 +++++++++++++++++++++-
> >>  1 file changed, 268 insertions(+), 4 deletions(-)
> >> 
> >> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> >> b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index
> >> fec4a4bcd1fe..15048ad694bc 100644
> >> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> >> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> >> @@ -2095,11 +2095,10 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi,
> >> struct drm_display_mode *mode)
> >> hdmi->hdmi_data.video_mode.mpixelrepetitionoutput = 0;
> >> 
> >>  	hdmi->hdmi_data.video_mode.mpixelrepetitioninput = 0;
> >> 
> >> -	/* TOFIX: Get input format from plat data or fallback to RGB888 */
> >> 
> >>  	if (hdmi->plat_data->input_bus_format)
> >>  	
> >>  		hdmi->hdmi_data.enc_in_bus_format =
> >>  		
> >>  			hdmi->plat_data->input_bus_format;
> >> 
> >> -	else
> >> +	else if (hdmi->hdmi_data.enc_in_bus_format == MEDIA_BUS_FMT_FIXED)
> >> 
> >>  		hdmi->hdmi_data.enc_in_bus_format =
> > 
> > MEDIA_BUS_FMT_RGB888_1X24;
> > 
> >>  	/* TOFIX: Get input encoding from plat data or fallback to none */
> >> 
> >> @@ -2109,8 +2108,8 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi,
> >> struct
> >> drm_display_mode *mode) else
> >> 
> >>  		hdmi->hdmi_data.enc_in_encoding =
> > 
> > V4L2_YCBCR_ENC_DEFAULT;
> > 
> >> -	/* TOFIX: Default to RGB888 output format */
> >> -	hdmi->hdmi_data.enc_out_bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> >> +	if (hdmi->hdmi_data.enc_out_bus_format == MEDIA_BUS_FMT_FIXED)
> >> +		hdmi->hdmi_data.enc_out_bus_format =
> > 
> > MEDIA_BUS_FMT_RGB888_1X24;
> > 
> >>  	hdmi->hdmi_data.pix_repet_factor = 0;
> >>  	hdmi->hdmi_data.hdcp_enable = 0;
> >> 
> >> @@ -2388,6 +2387,267 @@ static const struct drm_connector_helper_funcs
> >> dw_hdmi_connector_helper_funcs = .atomic_check =
> >> dw_hdmi_connector_atomic_check,
> >> 
> >>  };
> >> 
> >> +/*
> >> + * Possible output formats :
> >> + * - MEDIA_BUS_FMT_UYYVYY16_0_5X48,
> >> + * - MEDIA_BUS_FMT_UYYVYY12_0_5X36,
> >> + * - MEDIA_BUS_FMT_UYYVYY10_0_5X30,
> >> + * - MEDIA_BUS_FMT_UYYVYY8_0_5X24,
> >> + * - MEDIA_BUS_FMT_YUV16_1X48,
> >> + * - MEDIA_BUS_FMT_RGB161616_1X48,
> >> + * - MEDIA_BUS_FMT_UYVY12_1X24,
> >> + * - MEDIA_BUS_FMT_YUV12_1X36,
> >> + * - MEDIA_BUS_FMT_RGB121212_1X36,
> >> + * - MEDIA_BUS_FMT_UYVY10_1X20,
> >> + * - MEDIA_BUS_FMT_YUV10_1X30,
> >> + * - MEDIA_BUS_FMT_RGB101010_1X30,
> >> + * - MEDIA_BUS_FMT_UYVY8_1X16,
> >> + * - MEDIA_BUS_FMT_YUV8_1X24,
> >> + * - MEDIA_BUS_FMT_RGB888_1X24,
> >> + */
> >> +
> >> +/* Can return a maximum of 12 possible output formats for a
> >> mode/connector
> >> */ +#define MAX_OUTPUT_SEL_FORMATS	12
> >> +
> >> +static u32 *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)
> > 
> >> +{
> >> +	struct drm_connector *conn = conn_state->connector;
> >> +	struct drm_display_info *info = &conn->display_info;
> >> +	struct drm_display_mode *mode = &crtc_state->mode;
> >> +	u8 max_bpc = conn_state->max_requested_bpc;
> >> +	bool is_hdmi2_sink = info->hdmi.scdc.supported ||
> >> +			     (info->color_formats &
> > 
> > DRM_COLOR_FORMAT_YCRCB420);
> > 
> >> +	u32 *output_fmts;
> >> +	int i = 0;
> >> +
> >> +	*num_output_fmts = 0;
> >> +
> >> +	output_fmts = kcalloc(MAX_OUTPUT_SEL_FORMATS, 
sizeof(*output_fmts),
> >> +			      GFP_KERNEL);
> >> +	if (!output_fmts)
> >> +		return NULL;
> >> +
> >> +	/*
> >> +	 * 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 (conn->ycbcr_420_allowed &&
> >> +	    (drm_mode_is_420_only(info, mode) ||
> >> +	     ())) {
> >> +
> >> +		/* Order bus formats from 16bit to 8bit if supported */
> >> +		if (max_bpc >= 16 && info->bpc == 16 &&
> >> +		    (info->hdmi.y420_dc_modes &
> > 
> > DRM_EDID_YCBCR420_DC_48))
> > 
> >> +			output_fmts[i++] =
> > 
> > MEDIA_BUS_FMT_UYYVYY16_0_5X48;
> > 
> >> +
> >> +		if (max_bpc >= 12 && info->bpc >= 12 &&
> >> +		    (info->hdmi.y420_dc_modes &
> > 
> > DRM_EDID_YCBCR420_DC_36))
> > 
> >> +			output_fmts[i++] =
> > 
> > MEDIA_BUS_FMT_UYYVYY12_0_5X36;
> > 
> >> +
> >> +		if (max_bpc >= 10 && info->bpc >= 10 &&
> >> +		    (info->hdmi.y420_dc_modes &
> > 
> > DRM_EDID_YCBCR420_DC_30))
> > 
> >> +			output_fmts[i++] =
> > 
> > MEDIA_BUS_FMT_UYYVYY10_0_5X30;
> > 
> >> +
> >> +		/* Default 8bit fallback */
> >> +		output_fmts[i++] = MEDIA_BUS_FMT_UYYVYY8_0_5X24;
> >> +
> >> +		*num_output_fmts = i;
> >> +
> >> +		return output_fmts;
> > 
> > Driver shouldn't return just yet for case "is_hdmi2_sink &&
> > drm_mode_is_420_also(info, mode)", because monitor/TV also supports YCbCr
> > 4:4:4 in that case. IMO YCbCr 4:4:4 should be even prefered. What do you
> > think?
> 
> I think we need to have some way for controller driver and userspace to
> control what hdmi output format gets selected. I know for a fact that some
> Samsung TV have issues with 444 YCbCr modes at 4k 50/60hz but have no
> problems with 420 modes. The Samsung TV edid lie and/or the TV is not fully
> following HDMI specs

Interesting, maybe just some bandwith issues? I guess we should have a 
blacklist for such cases. I know that at least Allwinner BSP driver for DW 
HDMI has a blacklist, in this case for 2 monitors which claim to support YCbCr 
4:4:4 mode but they not.

> 
> From a personal and mediaplayer userspace perspective I would like to prefer
> 420/444 YCbCr mode as soon as any yuv drm plane is active and rgb 444
> anytime else.

I would argue that YCbCr is always prefered:
- CEA 861 prefers it for all CEA modes
- avoid dealing with quantization range - it's always limited range for < hdmi 
2.0 and selectable on some hdmi 2.0 capable sinks

Anyway, there is no universal solution to avoid color space conversion in all 
cases. For example, due to design of Allwinner Display Engine 2, it can only 
work in RGB format internally, but it can convert final output to YCbCr right 
before it's feeded to DW HDMI. On the other hand, you have meson display 
pipeline which works in YCbCr format internally and relies on DW HDMI CSC unit 
to convert output to RGB. Fortunately, there are also display pipelines which 
can work in any colorspace internally, like Allwinner Display Engine 3. Not 
sure in which category Rockchip display pipeline falls into.

> 
> On Rockchip SoCs the display controller cannot output yuv422 to dw-hdmi
> block, the optimal output format selection in such case should put yuv422
> last.

Note that DW HDMI has decimation support which converts 444 to 422. This is 
part of CSC unit.

Side note: CSC unit is optional feature of DW-HDMI and presence is indicated 
by config register. However, it seems that CSC support is broken in DW HDMI 
controller on 40nm Allwinner SoCs. If it is enabled, TV loses signal. I have 
to investigate if only CSC is broken or decimation also don't work.

> 
> Maybe dw-hdmi can call a dw-hdmi glue driver callback to get the preferred
> output format order?
> 
> On a side note but related issue, the dw-hdmi format negotiation code should
> probably also filter modes on tmds rate, something like [1].
> It is needed to filter out deep color modes that is not supported by the
> sink or hdmi spec.

Ah, you mean on TMDS rates supported by the sink. Could this avoid Samsung 
deep color issues? If so, we don't need blacklist then.

Best regards,
Jernej

> 
> [1]
> https://github.com/Kwiboo/linux-rockchip/commit/fc3df6903384e764ab6ac59879c
> 489cbef55fcbe
> 
> Best regards,
> Jonas
> 
> > Best regards,
> > Jernej
> > 
> >> +	}
> >> +
> >> +	/*
> >> +	 * Order bus formats from 16bit to 8bit and from YUV422 to RGB
> >> +	 * if supported. In any case the default RGB888 format is added
> >> +	 */
> >> +
> >> +	if (max_bpc >= 16 && info->bpc == 16) {
> >> +		if (info->color_formats & DRM_COLOR_FORMAT_YCRCB444)
> >> +			output_fmts[i++] = MEDIA_BUS_FMT_YUV16_1X48;
> >> +
> >> +		output_fmts[i++] = MEDIA_BUS_FMT_RGB161616_1X48;
> >> +	}
> >> +
> >> +	if (max_bpc >= 12 && info->bpc >= 12) {
> >> +		if (info->color_formats & DRM_COLOR_FORMAT_YCRCB422)
> >> +			output_fmts[i++] = 
MEDIA_BUS_FMT_UYVY12_1X24;
> >> +
> >> +		if (info->color_formats & DRM_COLOR_FORMAT_YCRCB444)
> >> +			output_fmts[i++] = MEDIA_BUS_FMT_YUV12_1X36;
> >> +
> >> +		output_fmts[i++] = MEDIA_BUS_FMT_RGB121212_1X36;
> >> +	}
> >> +
> >> +	if (max_bpc >= 10 && info->bpc >= 10) {
> >> +		if (info->color_formats & DRM_COLOR_FORMAT_YCRCB422)
> >> +			output_fmts[i++] = 
MEDIA_BUS_FMT_UYVY10_1X20;
> >> +
> >> +		if (info->color_formats & DRM_COLOR_FORMAT_YCRCB444)
> >> +			output_fmts[i++] = MEDIA_BUS_FMT_YUV10_1X30;
> >> +
> >> +		output_fmts[i++] = MEDIA_BUS_FMT_RGB101010_1X30;
> >> +	}
> >> +
> >> +	if (info->color_formats & DRM_COLOR_FORMAT_YCRCB422)
> >> +		output_fmts[i++] = MEDIA_BUS_FMT_UYVY8_1X16;
> >> +
> >> +	if (info->color_formats & DRM_COLOR_FORMAT_YCRCB444)
> >> +		output_fmts[i++] = MEDIA_BUS_FMT_YUV8_1X24;
> >> +
> >> +	/* Default 8bit RGB fallback */
> >> +	output_fmts[i++] = MEDIA_BUS_FMT_RGB888_1X24;
> >> +
> >> +	*num_output_fmts = i;
> >> +
> >> +	return output_fmts;
> >> +}
> >> +
> >> +/*
> >> + * Possible input formats :
> >> + * - MEDIA_BUS_FMT_RGB888_1X24
> >> + * - MEDIA_BUS_FMT_YUV8_1X24
> >> + * - MEDIA_BUS_FMT_UYVY8_1X16
> >> + * - MEDIA_BUS_FMT_UYYVYY8_0_5X24
> >> + * - MEDIA_BUS_FMT_RGB101010_1X30
> >> + * - MEDIA_BUS_FMT_YUV10_1X30
> >> + * - MEDIA_BUS_FMT_UYVY10_1X20
> >> + * - MEDIA_BUS_FMT_UYYVYY10_0_5X30
> >> + * - MEDIA_BUS_FMT_RGB121212_1X36
> >> + * - MEDIA_BUS_FMT_YUV12_1X36
> >> + * - MEDIA_BUS_FMT_UYVY12_1X24
> >> + * - MEDIA_BUS_FMT_UYYVYY12_0_5X36
> >> + * - MEDIA_BUS_FMT_RGB161616_1X48
> >> + * - MEDIA_BUS_FMT_YUV16_1X48
> >> + * - MEDIA_BUS_FMT_UYYVYY16_0_5X48
> >> + */
> >> +
> >> +/* Can return a maximum of 4 possible input formats for an output format
> >> */ +#define MAX_INPUT_SEL_FORMATS	4
> >> +
> >> +static u32 *dw_hdmi_bridge_atomic_get_input_bus_fmts(struct drm_bridge
> >> *bridge, +					struct
> > 
> > drm_bridge_state *bridge_state,
> > 
> >> +					struct drm_crtc_state
> > 
> > *crtc_state,
> > 
> >> +					struct
> > 
> > drm_connector_state *conn_state,
> > 
> >> +					u32 output_fmt,
> >> +					unsigned int
> > 
> > *num_input_fmts)
> > 
> >> +{
> >> +	u32 *input_fmts;
> >> +	int i = 0;
> >> +
> >> +	*num_input_fmts = 0;
> >> +
> >> +	input_fmts = kcalloc(MAX_INPUT_SEL_FORMATS, sizeof(*input_fmts),
> >> +			     GFP_KERNEL);
> >> +	if (!input_fmts)
> >> +		return NULL;
> >> +
> >> +	switch (output_fmt) {
> >> +	/* 8bit */
> >> +	case MEDIA_BUS_FMT_RGB888_1X24:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB888_1X24;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV8_1X24;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_UYVY8_1X16;
> >> +		break;
> >> +	case MEDIA_BUS_FMT_YUV8_1X24:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV8_1X24;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_UYVY8_1X16;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB888_1X24;
> >> +		break;
> >> +	case MEDIA_BUS_FMT_UYVY8_1X16:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_UYVY8_1X16;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV8_1X24;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB888_1X24;
> >> +		break;
> >> +
> >> +	/* 10bit */
> >> +	case MEDIA_BUS_FMT_RGB101010_1X30:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB101010_1X30;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV10_1X30;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_UYVY10_1X20;
> >> +		break;
> >> +	case MEDIA_BUS_FMT_YUV10_1X30:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV10_1X30;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_UYVY10_1X20;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB101010_1X30;
> >> +		break;
> >> +	case MEDIA_BUS_FMT_UYVY10_1X20:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_UYVY10_1X20;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV10_1X30;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB101010_1X30;
> >> +		break;
> >> +
> >> +	/* 12bit */
> >> +	case MEDIA_BUS_FMT_RGB121212_1X36:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB121212_1X36;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV12_1X36;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_UYVY12_1X24;
> >> +		break;
> >> +	case MEDIA_BUS_FMT_YUV12_1X36:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV12_1X36;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_UYVY12_1X24;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB121212_1X36;
> >> +		break;
> >> +	case MEDIA_BUS_FMT_UYVY12_1X24:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_UYVY12_1X24;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV12_1X36;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB121212_1X36;
> >> +		break;
> >> +
> >> +	/* 16bit */
> >> +	case MEDIA_BUS_FMT_RGB161616_1X48:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB161616_1X48;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV16_1X48;
> >> +		break;
> >> +	case MEDIA_BUS_FMT_YUV16_1X48:
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_YUV16_1X48;
> >> +		input_fmts[i++] = MEDIA_BUS_FMT_RGB161616_1X48;
> >> +		break;
> >> +
> >> +	/* 420 */
> >> +	case MEDIA_BUS_FMT_UYYVYY8_0_5X24:
> >> +	case MEDIA_BUS_FMT_UYYVYY10_0_5X30:
> >> +	case MEDIA_BUS_FMT_UYYVYY12_0_5X36:
> >> +	case MEDIA_BUS_FMT_UYYVYY16_0_5X48:
> >> +		input_fmts[i++] = output_fmt;
> >> +		break;
> >> +	}
> >> +
> >> +	*num_input_fmts = i;
> >> +
> >> +	if (*num_input_fmts == 0) {
> >> +		kfree(input_fmts);
> >> +		input_fmts = NULL;
> >> +	}
> >> +
> >> +	return input_fmts;
> >> +}
> >> +
> >> +static int dw_hdmi_bridge_atomic_check(struct drm_bridge *bridge,
> >> +				       struct drm_bridge_state
> > 
> > *bridge_state,
> > 
> >> +				       struct drm_crtc_state
> > 
> > *crtc_state,
> > 
> >> +				       struct drm_connector_state
> > 
> > *conn_state)
> > 
> >> +{
> >> +	struct dw_hdmi *hdmi = bridge->driver_private;
> >> +
> >> +	dev_dbg(hdmi->dev, "selected output format %x\n",
> >> +			bridge_state->output_bus_cfg.format);
> >> +
> >> +	hdmi->hdmi_data.enc_out_bus_format =
> >> +			bridge_state->output_bus_cfg.format;
> >> +
> >> +	dev_dbg(hdmi->dev, "selected input format %x\n",
> >> +			bridge_state->input_bus_cfg.format);
> >> +
> >> +	hdmi->hdmi_data.enc_in_bus_format =
> >> +			bridge_state->input_bus_cfg.format;
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> 
> >>  static int dw_hdmi_bridge_attach(struct drm_bridge *bridge)
> >>  {
> >>  
> >>  	struct dw_hdmi *hdmi = bridge->driver_private;
> >> 
> >> @@ -2499,6 +2759,9 @@ static const struct drm_bridge_funcs
> >> dw_hdmi_bridge_funcs = { .atomic_reset = drm_atomic_helper_bridge_reset,
> >> 
> >>  	.attach = dw_hdmi_bridge_attach,
> >>  	.detach = dw_hdmi_bridge_detach,
> >> 
> >> +	.atomic_check = dw_hdmi_bridge_atomic_check,
> >> +	.atomic_get_output_bus_fmts =
> > 
> > dw_hdmi_bridge_atomic_get_output_bus_fmts,
> > 
> >> +	.atomic_get_input_bus_fmts =
> > 
> > dw_hdmi_bridge_atomic_get_input_bus_fmts,
> > 
> >>  	.enable = dw_hdmi_bridge_enable,
> >>  	.disable = dw_hdmi_bridge_disable,
> >>  	.mode_set = dw_hdmi_bridge_mode_set,
> >> 
> >> @@ -2963,6 +3226,7 @@ __dw_hdmi_probe(struct platform_device *pdev,
> >> 
> >>  	hdmi->bridge.driver_private = hdmi;
> >>  	hdmi->bridge.funcs = &dw_hdmi_bridge_funcs;
> >> 
> >> +
> >> 
> >>  #ifdef CONFIG_OF
> >>  
> >>  	hdmi->bridge.of_node = pdev->dev.of_node;
> >>  
> >>  #endif

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