RE: dw_hdmi is showing wrong colour after commit 7cd70656d1285b79("drm/bridge: display-connector: implement bus fmts callbacks")

[Biju Das]

> -----Original Message-----
> From: Neil Armstrong <narmstrong@xxxxxxxxxxxx>
> Sent: 14 January 2022 13:56
> To: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>; Fabio Estevam
> <festevam@xxxxxxxxx>
> Cc: daniel@xxxxxxxx; Laurent.pinchart@xxxxxxxxxxxxxxxx;
> robert.foss@xxxxxxxxxx; jonas@xxxxxxxxx; jernej.skrabec@xxxxxxxxx;
> martin.blumenstingl@xxxxxxxxxxxxxx; linux-amlogic@xxxxxxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; linux-renesas-soc@xxxxxxxxxxxxxxx
> Subject: Re: dw_hdmi is showing wrong colour after commit
> 7cd70656d1285b79("drm/bridge: display-connector: implement bus fmts
> callbacks")
> 
> Hi,
> 
> On 14/01/2022 12:08, Biju Das wrote:
> > Hi Neil,
> >
> >> Subject: Re: dw_hdmi is showing wrong colour after commit
> >> 7cd70656d1285b79("drm/bridge: display-connector: implement bus fmts
> >> callbacks")
> >>
> >> On 14/01/2022 09:29, Biju Das wrote:
> >>> Hi Neil,
> >>>
> >>> + renesas-soc
> >>>
> >>>> Subject: Re: dw_hdmi is showing wrong colour after commit
> >>>> 7cd70656d1285b79("drm/bridge: display-connector: implement bus fmts
> >>>> callbacks")
> >>>>
> >>>> Hi,
> >>>>
> >>>> On 13/01/2022 21:01, Fabio Estevam wrote:
> >>>>> Hi Biju,
> >>>>>
> >>>>> On Thu, Jan 13, 2022 at 2:45 PM Biju Das
> >>>>> <biju.das.jz@xxxxxxxxxxxxxx>
> >>>> wrote:
> >>>>>>
> >>>>>> Hi All,
> >>>>>>
> >>>>>> RZ/G2{H, M, N} SoC has dw_hdmi IP and it was working ok(colour)
> >>>>>> till the commit
> >>>>>> 7cd70656d1285b79("drm/bridge: display-connector: implement bus
> >>>>>> fmts
> >>>> callbacks").
> >>>>>>
> >>>>>> After this patch, the screen becomes greenish(may be it is
> >>>>>> setting it
> >>>> into YUV format??).
> >>>>>>
> >>>>>> By checking the code, previously it used to call get_input_fmt
> >>>>>> callback
> >>>> and set colour as RGB24.
> >>>>>>
> >>>>>> After this commit, it calls get_output_fmt_callbck and returns 3
> >>>>>> outputformats(YUV16, YUV24 and RGB24) And get_input_fmt callback,
> >>>>>> I see
> >>>> the outputformat as YUV16 instead of RGB24.
> >>>>>>
> >>>>>> Not sure, I am the only one seeing this issue with dw_HDMI driver.
> >>>>
> >>>> This patch was introduced to maintain the bridge color format
> >>>> negotiation after using DRM_BRIDGE_ATTACH_NO_CONNECTOR, but it
> >>>> seems it behaves incorrectly if the first bridge doesn't implement
> >>>> the negotiation callbacks.
> >>>>
> >>>> Let me check the code to see how to fix that.
> >>>
> >>> Thanks for the information, I am happy to test the patch/fix.
> >>>
> >>> Cheers,
> >>> Biju
> >>>
> >>>>
> >>>>>
> >>>>> I have tested linux-next 20220112 on a imx6q-sabresd board, which
> >> shows:
> >>>>>
> >>>>> dwhdmi-imx 120000.hdmi: Detected HDMI TX controller v1.30a with
> >>>>> HDCP (DWC HDMI 3D TX PHY)
> >>>>>
> >>>>> The colors are shown correctly here.
> >>>>>
> >>>>
> >>>> The imx doesn't use DRM_BRIDGE_ATTACH_NO_CONNECTOR so the
> >>>> negotiation fails and use the RGB fallback input & output format.
> >>>>
> >>>> Anyway thanks for testing
> >>>>
> >>>> Neil
> >>
> >> Can you test :
> >>
> >> ==><===============================
> >> diff --git a/drivers/gpu/drm/drm_bridge.c
> >> b/drivers/gpu/drm/drm_bridge.c index c96847fc0ebc..7019acd37716
> >> 100644
> >> --- a/drivers/gpu/drm/drm_bridge.c
> >> +++ b/drivers/gpu/drm/drm_bridge.c
> >> @@ -955,7 +955,14 @@ drm_atomic_bridge_chain_select_bus_fmts(struct
> >> drm_bridge *bridge,
> >>         last_bridge_state =
> >> drm_atomic_get_new_bridge_state(crtc_state-
> >>> state,
> >>
> >> last_bridge);
> >>
> >> -       if (last_bridge->funcs->atomic_get_output_bus_fmts) {
> >> +       /*
> >> +        * Only negociate with real values if both end of the bridge
> chain
> >> +        * support negociation callbacks, otherwise you can end in a
> >> situation
> >> +        * where the selected output format doesn't match with the
> >> + first
> >> bridge
> >> +        * output format.
> >> +        */
> >> +       if (bridge->funcs->atomic_get_input_bus_fmts &&
> >> +           last_bridge->funcs->atomic_get_output_bus_fmts) {
> >>                 const struct drm_bridge_funcs *funcs =
> >> last_bridge->funcs;
> >>
> >>                 /*
> >> @@ -980,7 +987,12 @@ drm_atomic_bridge_chain_select_bus_fmts(struct
> >> drm_bridge *bridge,
> >>                 if (!out_bus_fmts)
> >>                         return -ENOMEM;
> >>
> >> -               if (conn->display_info.num_bus_formats &&
> >> +               /*
> >> +                * If first bridge doesn't support negociation, use
> >> MEDIA_BUS_FMT_FIXED
> >> +                * as a safe value for the whole bridge chain
> >> +                */
> >> +               if (bridge->funcs->atomic_get_input_bus_fmts &&
> >> +                   conn->display_info.num_bus_formats &&
> >>                     conn->display_info.bus_formats)
> >>                         out_bus_fmts[0] = conn-
> >>> display_info.bus_formats[0];
> >>                 else
> >> ==><===============================
> >>
> >> This should exclude your situation where the first bridge doesn't
> >> support negociation.
> >
> > I have tested this fix with Linux next-20220114. Still I see colour
> issue.
> >
> > It is still negotiating and it is calling get_output_fmt_callbck
> >
> > [    3.460155] ########dw_hdmi_bridge_atomic_get_output_bus_fmts
> MEDIA_BUS_FMT_UYVY8_1X16=0#########
> > [    3.460180] ########dw_hdmi_bridge_atomic_get_output_bus_fmts
> MEDIA_BUS_FMT_YUV8_1X24=1#########
> > [    3.460202] ########dw_hdmi_bridge_atomic_get_output_bus_fmts
> MEDIA_BUS_FMT_RGB888_1X24=2#########
> >
> > And In get_input_fmt callback, I See the outputformat as YUV16 instead
> of RGB24.
> >
> > [    3.460319] ########dw_hdmi_bridge_atomic_get_input_bus_fmts
> MEDIA_BUS_FMT_UYVY8_1X16#########
> > [    3.473644] ########hdmi_video_sample
> MEDIA_BUS_FMT_UYVY8_1X16#########
> 
> OK, looking at rcar-du, the dw-hdmi bridge is directly connected to the
> encoder.

Yep.

> 
> Let me figure that out, no sure I can find a clean solution except putting
> back RGB24 before YUV.
> 
> Anyway please test that:

It works now after reordering.

[    3.493302] ########dw_hdmi_bridge_atomic_get_output_bus_fmts MEDIA_BUS_FMT_RGB888_1X24=0#########
[    3.493326] ########dw_hdmi_bridge_atomic_get_output_bus_fmts MEDIA_BUS_FMT_YUV8_1X24=1#########
[    3.493348] ########dw_hdmi_bridge_atomic_get_output_bus_fmts MEDIA_BUS_FMT_UYVY8_1X16=2#########

[    3.493463] ########dw_hdmi_bridge_atomic_get_input_bus_fmts MEDIA_BUS_FMT_RGB888_1X24#########
[    3.506797] ########hdmi_video_sample MEDIA_BUS_FMT_RGB888_1X24#########

Is it acceptable solution to the users of dw_hdmi driver? May be it is worth to post a patch.
at least it is fixing the colour issue??

Regards,
Biju

> 
> ==><===============================
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index 54d8fdad395f..68f79094f648 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -2589,45 +2589,44 @@ static u32
> *dw_hdmi_bridge_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
>  	}
> 
>  	/*
> -	 * Order bus formats from 16bit to 8bit and from YUV422 to RGB
> +	 * Order bus formats from 16bit to 8bit and from RGB to YUV422
>  	 * if supported. In any case the default RGB888 format is added
>  	 */
> 
>  	if (max_bpc >= 16 && info->bpc == 16) {
> +		output_fmts[i++] = MEDIA_BUS_FMT_RGB161616_1X48;
> +
>  		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;
> +		output_fmts[i++] = MEDIA_BUS_FMT_RGB121212_1X36;
> 
>  		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 (info->color_formats & DRM_COLOR_FORMAT_YCRCB422)
> +			output_fmts[i++] = MEDIA_BUS_FMT_UYVY12_1X24;
>  	}
> 
>  	if (max_bpc >= 10 && info->bpc >= 10) {
> -		if (info->color_formats & DRM_COLOR_FORMAT_YCRCB422)
> -			output_fmts[i++] = MEDIA_BUS_FMT_UYVY10_1X20;
> +		output_fmts[i++] = MEDIA_BUS_FMT_RGB101010_1X30;
> 
>  		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_UYVY10_1X20;
>  	}
> 
> -	if (info->color_formats & DRM_COLOR_FORMAT_YCRCB422)
> -		output_fmts[i++] = MEDIA_BUS_FMT_UYVY8_1X16;
> +	output_fmts[i++] = MEDIA_BUS_FMT_RGB888_1X24;
> 
>  	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;
> +	if (info->color_formats & DRM_COLOR_FORMAT_YCRCB422)
> +		output_fmts[i++] = MEDIA_BUS_FMT_UYVY8_1X16;
> 
>  	*num_output_fmts = i;
> 
> ==><===============================
> 
> Neil
> 
> >
> > Regards,
> > Biju
> >