linux-kernel - Re: [PATCH 3/6] drm: bridge: dw-hdmi: Introduce previous_pixelclock/previous

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Message-ID: <fd42150f-45fc-1664-eeab-7b8e9e99ed60@baylibre.com>
Date:   Mon, 24 Aug 2020 11:53:30 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Algea Cao <algea.cao@...k-chips.com>, a.hajda@...sung.com,
        kuankuan.y@...il.com, hjc@...k-chips.com, tzimmermann@...e.de,
        dri-devel@...ts.freedesktop.org, sam@...nborg.org,
        airlied@...ux.ie, heiko@...ech.de, jernej.skrabec@...l.net,
        Laurent.pinchart@...asonboard.com,
        laurent.pinchart+renesas@...asonboard.com, jonas@...boo.se,
        mripard@...nel.org, darekm@...gle.com,
        linux-rockchip@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, cychiang@...omium.org,
        linux-kernel@...r.kernel.org, jbrunet@...libre.com,
        maarten.lankhorst@...ux.intel.com, daniel@...ll.ch
Subject: Re: [PATCH 3/6] drm: bridge: dw-hdmi: Introduce
 previous_pixelclock/previous_tmdsclock

On 12/08/2020 10:34, Algea Cao wrote:
> Introduce previous_pixelclock/previous_tmdsclock to
> determine whether PHY needs initialization. If phy is power off,
> or mpixelclock/mtmdsclock is different to previous value, phy is
> neet to be reinitialized.
> 
> Signed-off-by: Algea Cao <algea.cao@...k-chips.com>
> ---
> 
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 50 +++++++++++++++++++----
>  1 file changed, 43 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index a1a81fc768c2..1eb4736b9b59 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -101,6 +101,8 @@ static const u16 csc_coeff_rgb_full_to_rgb_limited[3][4] = {
>  struct hdmi_vmode {
>  	bool mdataenablepolarity;
>  
> +	unsigned int previous_pixelclock;
> +	unsigned int previous_tmdsclock;
>  	unsigned int mpixelclock;
>  	unsigned int mpixelrepetitioninput;
>  	unsigned int mpixelrepetitionoutput;
> @@ -890,6 +892,32 @@ static int hdmi_bus_fmt_color_depth(unsigned int bus_format)
>  	}
>  }
>  
> +static unsigned int
> +hdmi_get_tmdsclock(struct dw_hdmi *hdmi, unsigned long mpixelclock)
> +{
> +	unsigned int tmdsclock = mpixelclock;
> +	unsigned int depth =
> +		hdmi_bus_fmt_color_depth(hdmi->hdmi_data.enc_out_bus_format);
> +
> +	if (!hdmi_bus_fmt_is_yuv422(hdmi->hdmi_data.enc_out_bus_format)) {
> +		switch (depth) {
> +		case 16:
> +			tmdsclock = mpixelclock * 2;
> +			break;
> +		case 12:
> +			tmdsclock = mpixelclock * 3 / 2;
> +			break;
> +		case 10:
> +			tmdsclock = mpixelclock * 5 / 4;
> +			break;
> +		default:
> +			break;
> +		}
> +	}


Where does this come from ? Please introduce this on another patch.

Neil

> +
> +	return tmdsclock;
> +}
> +
>  /*
>   * this submodule is responsible for the video data synchronization.
>   * for example, for RGB 4:4:4 input, the data map is defined as
> @@ -1861,11 +1889,13 @@ static void hdmi_av_composer(struct dw_hdmi *hdmi,
>  	int hblank, vblank, h_de_hs, v_de_vs, hsync_len, vsync_len;
>  	unsigned int vdisplay, hdisplay;
>  
> +	vmode->previous_pixelclock = vmode->mpixelclock;
>  	vmode->mpixelclock = mode->clock * 1000;
>  
>  	dev_dbg(hdmi->dev, "final pixclk = %d\n", vmode->mpixelclock);
>  
> -	vmode->mtmdsclock = vmode->mpixelclock;
> +	vmode->previous_tmdsclock = vmode->mtmdsclock;
> +	vmode->mtmdsclock = hdmi_get_tmdsclock(hdmi, vmode->mpixelclock);
>  
>  	if (!hdmi_bus_fmt_is_yuv422(hdmi->hdmi_data.enc_out_bus_format)) {
>  		switch (hdmi_bus_fmt_color_depth(
> @@ -2172,12 +2202,18 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi,
>  	hdmi_av_composer(hdmi, &connector->display_info, mode);
>  
>  	/* HDMI Initializateion Step B.2 */
> -	ret = hdmi->phy.ops->init(hdmi, hdmi->phy.data,
> -				  &connector->display_info,
> -				  &hdmi->previous_mode);
> -	if (ret)
> -		return ret;
> -	hdmi->phy.enabled = true;
> +	if (!hdmi->phy.enabled ||
> +	    hdmi->hdmi_data.video_mode.previous_pixelclock !=
> +	    hdmi->hdmi_data.video_mode.mpixelclock ||
> +	    hdmi->hdmi_data.video_mode.previous_tmdsclock !=
> +	    hdmi->hdmi_data.video_mode.mtmdsclock) {
> +		ret = hdmi->phy.ops->init(hdmi, hdmi->phy.data,
> +					  &connector->display_info,
> +					  &hdmi->previous_mode);
> +		if (ret)
> +			return ret;
> +		hdmi->phy.enabled = true;
> +	}
>  
>  	/* HDMI Initialization Step B.3 */
>  	dw_hdmi_enable_video_path(hdmi);
>