linux-kernel - Re: [RFC/RFT PATCH 4/4] drm/bridge: dw-hdmi: Take input format from plat

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Message-ID: <5448085.cpOE2LFyiJ@avalon>
Date:   Tue, 17 Jan 2017 16:48:41 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     dri-devel@...ts.freedesktop.org,
        laurent.pinchart+renesas@...asonboard.com, Jose.Abreu@...opsys.com,
        kieran.bingham@...asonboard.com, linux-amlogic@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC/RFT PATCH 4/4] drm/bridge: dw-hdmi: Take input format from plat_data

Hi Neil,

Thank you for the patch.

On Tuesday 17 Jan 2017 13:31:34 Neil Armstrong wrote:
> Some display pipelines can only provide non-RBG input pixels to the HDMI TX
> Controller, this patch takes the pixel format from the plat_data if
> provided.
> 
> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
> ---
>  drivers/gpu/drm/bridge/dw-hdmi.c | 7 +++++--
>  include/drm/bridge/dw_hdmi.h     | 9 +++++++++
>  2 files changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c
> b/drivers/gpu/drm/bridge/dw-hdmi.c index 8a6a183..fa4147c 100644
> --- a/drivers/gpu/drm/bridge/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/dw-hdmi.c
> @@ -1420,8 +1420,11 @@ 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;
> 
> -	/* TODO: Get input format from IPU (via FB driver interface) */
> -	hdmi->hdmi_data.enc_in_format = RGB;
> +	/* Get input format from plat data or fallback to RGB */
> +	if (hdmi->plat_data->input_fmt >= 0)
> +		hdmi->hdmi_data.enc_in_format = hdmi->plat_data->input_fmt;
> +	else
> +		hdmi->hdmi_data.enc_in_format = RGB;

This should ideally be queried dynamically. I believe we need to extend the 
DRM bridge API for this purpose. I might be willing to accept a pdata-based 
solution in the meantime though.

>  	hdmi->hdmi_data.enc_out_format = RGB;
> 
> diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdmi.h
> index d6a0ab3..4f426c3 100644
> --- a/include/drm/bridge/dw_hdmi.h
> +++ b/include/drm/bridge/dw_hdmi.h
> @@ -21,6 +21,14 @@ enum {
>  	DW_HDMI_RES_MAX,
>  };
> 
> +enum {
> +	DW_HDMI_INPUT_FMT_RGB = 0,
> +	DW_HDMI_INPUT_FMT_YCBCR444,
> +	DW_HDMI_INPUT_FMT_YCBCR422_16BITS,
> +	DW_HDMI_INPUT_FMT_YCBCR422_8BITS,
> +	DW_HDMI_INPUT_FMT_XVYCC444,
> +};

How about giving the enum a name and dropping the

#define RGB                     0
#define YCBCR444                1
#define YCBCR422_16BITS         2
#define YCBCR422_8BITS          3
#define XVYCC444                4

macros from the driver ? Even better, how about using a media bus format code 
from include/uapi/linux/media-bus-format.h ? We would need an additional 
colorspace field to express the difference between the YCBCR and XVYCC 
formats, as both of them are YUV 4:4:4 and map to the same bus format.

>  enum dw_hdmi_phy_type {
>  	DW_HDMI_PHY_DWC_HDMI_TX_PHY = 0x00,
>  	DW_HDMI_PHY_DWC_MHL_PHY_HEAC = 0xb2,
> @@ -68,6 +76,7 @@ struct dw_hdmi_plat_data {
>  				 const struct dw_hdmi_plat_data *data);
>  	bool (*hdmi_read_hpd)(struct dw_hdmi *hdmi,
>  			      const struct dw_hdmi_plat_data *data);
> +	int input_fmt;
>  };
> 
>  int dw_hdmi_probe(struct platform_device *pdev,

-- 
Regards,

Laurent Pinchart