linux-kernel - Re: [PATCH v2 4/4] drm/bridge: dw-hdmi: rework csc related functions

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Message-ID: <20200304235149.GH28814@pendragon.ideasonboard.com>
Date:   Thu, 5 Mar 2020 01:51:49 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Jernej Skrabec <jernej.skrabec@...l.net>
Cc:     a.hajda@...sung.com, narmstrong@...libre.com, jonas@...boo.se,
        airlied@...ux.ie, daniel@...ll.ch, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] drm/bridge: dw-hdmi: rework csc related functions

Hi Jernej,

Thank you for the patch.

On Thu, Mar 05, 2020 at 12:25:12AM +0100, Jernej Skrabec wrote:
> is_color_space_conversion() is a misnomer. It checks not only if color
> space conversion is needed, but also if format conversion is needed.
> This is actually desired behaviour because result of this function
> determines if CSC block should be enabled or not (CSC block can also do
> format conversion).
> 
> In order to clear misunderstandings, let's rework
> is_color_space_conversion() to do exactly what is supposed to do and add
> another function which will determine if CSC block must be enabled or
> not.
> 
> Signed-off-by: Jernej Skrabec <jernej.skrabec@...l.net>
> ---
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 31 +++++++++++++++--------
>  1 file changed, 21 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index c8a02e5b5e1b..7724191e0a8b 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -963,11 +963,14 @@ static void hdmi_video_sample(struct dw_hdmi *hdmi)
>  
>  static int is_color_space_conversion(struct dw_hdmi *hdmi)
>  {
> -	return (hdmi->hdmi_data.enc_in_bus_format !=
> -			hdmi->hdmi_data.enc_out_bus_format) ||
> -	       (hdmi_bus_fmt_is_rgb(hdmi->hdmi_data.enc_in_bus_format) &&
> -		hdmi_bus_fmt_is_rgb(hdmi->hdmi_data.enc_out_bus_format) &&
> -		hdmi->hdmi_data.rgb_limited_range);
> +	struct hdmi_data_info *hdmi_data = &hdmi->hdmi_data;
> +	bool is_input_rgb, is_output_rgb;
> +
> +	is_input_rgb = hdmi_bus_fmt_is_rgb(hdmi_data->enc_in_bus_format);
> +	is_output_rgb = hdmi_bus_fmt_is_rgb(hdmi_data->enc_out_bus_format);
> +
> +	return (is_input_rgb != is_output_rgb) ||
> +	       (is_input_rgb && is_output_rgb && hdmi_data->rgb_limited_range);
>  }
>  
>  static int is_color_space_decimation(struct dw_hdmi *hdmi)
> @@ -994,6 +997,13 @@ static int is_color_space_interpolation(struct dw_hdmi *hdmi)
>  	return 0;
>  }
>  
> +static bool is_conversion_needed(struct dw_hdmi *hdmi)

Maybe is_csc_needed ?

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> +{
> +	return is_color_space_conversion(hdmi) ||
> +	       is_color_space_decimation(hdmi) ||
> +	       is_color_space_interpolation(hdmi);
> +}
> +
>  static void dw_hdmi_update_csc_coeffs(struct dw_hdmi *hdmi)
>  {
>  	const u16 (*csc_coeff)[3][4] = &csc_coeff_default;
> @@ -2014,18 +2024,19 @@ static void dw_hdmi_enable_video_path(struct dw_hdmi *hdmi)
>  	hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
>  
>  	/* Enable csc path */
> -	if (is_color_space_conversion(hdmi)) {
> +	if (is_conversion_needed(hdmi)) {
>  		hdmi->mc_clkdis &= ~HDMI_MC_CLKDIS_CSCCLK_DISABLE;
>  		hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
> -	}
>  
> -	/* Enable color space conversion if needed */
> -	if (is_color_space_conversion(hdmi))
>  		hdmi_writeb(hdmi, HDMI_MC_FLOWCTRL_FEED_THROUGH_OFF_CSC_IN_PATH,
>  			    HDMI_MC_FLOWCTRL);
> -	else
> +	} else {
> +		hdmi->mc_clkdis |= HDMI_MC_CLKDIS_CSCCLK_DISABLE;
> +		hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
> +
>  		hdmi_writeb(hdmi, HDMI_MC_FLOWCTRL_FEED_THROUGH_OFF_CSC_BYPASS,
>  			    HDMI_MC_FLOWCTRL);
> +	}
>  }
>  
>  /* Workaround to clear the overflow condition */

-- 
Regards,

Laurent Pinchart