linux-kernel - Re: [PATCH RFC v2 2/8] drm/meson: add HDMI div40 TMDS mode

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Message-ID: <2738985d-e2c6-905e-4148-69344fb50cc3@baylibre.com>
Date:   Tue, 18 Dec 2018 14:19:52 +0100
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Andrzej Hajda <a.hajda@...sung.com>, architt@...eaurora.org,
        Laurent.pinchart@...asonboard.com
Cc:     dri-devel@...ts.freedesktop.org, linux-amlogic@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC v2 2/8] drm/meson: add HDMI div40 TMDS mode

On 18/12/2018 13:36, Andrzej Hajda wrote:
> On 30.11.2018 14:42, Neil Armstrong wrote:
>> Add support for TMDS Clock > 3.4GHz for HDMI2.0 display modes.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>> ---
>>  drivers/gpu/drm/meson/meson_dw_hdmi.c | 24 ++++++++++++++++++++----
>>  1 file changed, 20 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
>> index 807111ebfdd9..b8775102b100 100644
>> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
>> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
>> @@ -365,7 +365,8 @@ static int dw_hdmi_phy_init(struct dw_hdmi *hdmi, void *data,
>>  	unsigned int wr_clk =
>>  		readl_relaxed(priv->io_base + _REG(VPU_HDMI_SETTING));
>>  
>> -	DRM_DEBUG_DRIVER("%d:\"%s\"\n", mode->base.id, mode->name);
>> +	DRM_DEBUG_DRIVER("%d:\"%s\" div%d\n", mode->base.id, mode->name,
>> +			 mode->clock > 340000 ? 40 : 10);
>>  
>>  	/* Enable clocks */
>>  	regmap_update_bits(priv->hhi, HHI_HDMI_CLK_CNTL, 0xffff, 0x100);
>> @@ -385,9 +386,17 @@ static int dw_hdmi_phy_init(struct dw_hdmi *hdmi, void *data,
>>  	/* Enable normal output to PHY */
>>  	dw_hdmi_top_write(dw_hdmi, HDMITX_TOP_BIST_CNTL, BIT(12));
>>  
>> -	/* TMDS pattern setup (TOFIX pattern for 4k2k scrambling) */
>> -	dw_hdmi_top_write(dw_hdmi, HDMITX_TOP_TMDS_CLK_PTTN_01, 0x001f001f);
>> -	dw_hdmi_top_write(dw_hdmi, HDMITX_TOP_TMDS_CLK_PTTN_23, 0x001f001f);
>> +	/* TMDS pattern setup (TOFIX Handle the YUV420 case) */
>> +	if (mode->clock > 340000) {
>> +		dw_hdmi_top_write(dw_hdmi, HDMITX_TOP_TMDS_CLK_PTTN_01, 0);
>> +		dw_hdmi_top_write(dw_hdmi, HDMITX_TOP_TMDS_CLK_PTTN_23,
>> +				  0x03ff03ff);
>> +	} else {
>> +		dw_hdmi_top_write(dw_hdmi, HDMITX_TOP_TMDS_CLK_PTTN_01,
>> +				  0x001f001f);
>> +		dw_hdmi_top_write(dw_hdmi, HDMITX_TOP_TMDS_CLK_PTTN_23,
>> +				  0x001f001f);
>> +	}
>>  
>>  	/* Load TMDS pattern */
>>  	dw_hdmi_top_write(dw_hdmi, HDMITX_TOP_TMDS_CLK_PTTN_CNTL, 0x1);
>> @@ -413,6 +422,8 @@ static int dw_hdmi_phy_init(struct dw_hdmi *hdmi, void *data,
>>  	/* Disable clock, fifo, fifo_wr */
>>  	regmap_update_bits(priv->hhi, HHI_HDMI_PHY_CNTL1, 0xf, 0);
>>  
>> +	dw_hdmi_set_high_tmds_clock_ratio(hdmi);
>> +
>>  	msleep(100);
>>  
>>  	/* Reset PHY 3 times in a row */
>> @@ -562,6 +573,11 @@ dw_hdmi_mode_valid(struct drm_connector *connector,
>>  		mode->vdisplay, mode->vsync_start,
>>  		mode->vsync_end, mode->vtotal, mode->type, mode->flags);
>>  
>> +	/* If sink max TMDS clock < 340MHz, we reject the HDMI2.0 modes */
>> +	if (mode->clock > 340000 &&
>> +	    connector->display_info.max_tmds_clock < 340000)
>> +		return MODE_BAD;
>> +
> 
> 
> Why not just:
> 
> if (mode->clock > connector->display_info.max_tmds_clock)
> 	return MODE_BAD;

Hmm, let me check, it may be better indeed.

Neil

> 
> 
> Regards
> 
> Andrzej
> 
> 
>>  	/* Check against non-VIC supported modes */
>>  	if (!vic) {
>>  		status = meson_venc_hdmi_supported_mode(mode);
> 
>