Re: [PATCH v2 7/8] drm/meson: Add YUV420 output support

From: Neil Armstrong <narmstrong@baylibre.com>
To: Maxime Jourdan <mjourdan@baylibre.com>
Cc: a.hajda@samsung.com, Laurent.pinchart@ideasonboard.com,
	p.zabel@pengutronix.de, Sandy Huang <hjc@rock-chips.com>,
	heiko@sntech.de, maxime.ripard@bootlin.com,
	linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2 7/8] drm/meson: Add YUV420 output support
Date: Tue, 19 Mar 2019 11:38:01 +0100	[thread overview]
Message-ID: <cd6b8fc6-82a7-faba-54d5-e271242ba024@baylibre.com> (raw)
In-Reply-To: <CAMO6nayWKDfcsQtrPK7-Pki75F5tAYO-0B=D=TAbGvQmt=gwrw@mail.gmail.com>

On 19/03/2019 11:35, Maxime Jourdan wrote:
> Hi Neil,
> 
> On Fri, Feb 1, 2019 at 1:08 PM Neil Armstrong <narmstrong@baylibre.com> wrote:
>>
>> This patch adds support for the YUV420 output from the Amlogic Meson SoCs
>> Video Processing Unit to the HDMI Controller.
>>
>> The YUV420 is obtained by generating a YUV444 pixel stream like
>> the classic HDMI display modes, but then the Video Encoder output
>> can be configured to down-sample the YUV444 pixel stream to a YUV420
>> stream.
>> In addition if pixel stream down-sampling, the Y Cb Cr components must
>> also be mapped differently to align with the HDMI2.0 specifications.
>>
>> This mode needs a different clock generation scheme since the TMDS PHY
>> clock must match the 10x ration with the YUV420 pixel clock, but
>> the video encoder must run at 2x the pixel clock.
>>
>> This patch adds the TMDS PHY clock value in all the video clock setup
>> in order to better support these specific uses cases and switch
>> to the Common Clock framework for clocks handling in the future.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> ---
>>  drivers/gpu/drm/meson/meson_dw_hdmi.c   | 110 ++++++++++++++++++++++++++------
>>  drivers/gpu/drm/meson/meson_vclk.c      |  93 ++++++++++++++++++++-------
>>  drivers/gpu/drm/meson/meson_vclk.h      |   7 +-
>>  drivers/gpu/drm/meson/meson_venc.c      |   6 +-
>>  drivers/gpu/drm/meson/meson_venc.h      |  11 ++++
>>  drivers/gpu/drm/meson/meson_venc_cvbs.c |   3 +-
>>  6 files changed, 184 insertions(+), 46 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
>> index e28814f..540971a 100644
>> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
>> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
>> @@ -141,6 +141,8 @@ struct meson_dw_hdmi {
>>         struct regulator *hdmi_supply;
>>         u32 irq_stat;
>>         struct dw_hdmi *hdmi;
>> +       unsigned long input_bus_format;
>> +       unsigned long output_bus_format;
>>  };
>>  #define encoder_to_meson_dw_hdmi(x) \
>>         container_of(x, struct meson_dw_hdmi, encoder)
>> @@ -323,25 +325,36 @@ static void dw_hdmi_set_vclk(struct meson_dw_hdmi *dw_hdmi,
>>  {
>>         struct meson_drm *priv = dw_hdmi->priv;
>>         int vic = drm_match_cea_mode(mode);
>> +       unsigned int phy_freq;
>>         unsigned int vclk_freq;
>>         unsigned int venc_freq;
>>         unsigned int hdmi_freq;
>>
>>         vclk_freq = mode->clock;
>>
>> +       /* For 420, pixel clock is half unlike venc clock */
>> +       if (dw_hdmi->input_bus_format == MEDIA_BUS_FMT_UYYVYY8_0_5X24)
>> +               vclk_freq /= 2;
>> +
>> +       /* TMDS clock is pixel_clock * 10 */
>> +       phy_freq = vclk_freq * 10;
>> +
>>         if (!vic) {
>> -               meson_vclk_setup(priv, MESON_VCLK_TARGET_DMT, vclk_freq,
>> -                                vclk_freq, vclk_freq, false);
>> +               meson_vclk_setup(priv, MESON_VCLK_TARGET_DMT, phy_freq,
>> +                                vclk_freq, vclk_freq, vclk_freq, false);
>>                 return;
>>         }
>>
>> +       /* 480i/576i needs global pixel doubling */
>>         if (mode->flags & DRM_MODE_FLAG_DBLCLK)
>>                 vclk_freq *= 2;
>>
>>         venc_freq = vclk_freq;
>>         hdmi_freq = vclk_freq;
>>
>> -       if (meson_venc_hdmi_venc_repeat(vic))
>> +       /* VENC double pixels for 1080i, 720p and YUV420 modes */
>> +       if (meson_venc_hdmi_venc_repeat(vic) ||
>> +           dw_hdmi->input_bus_format == MEDIA_BUS_FMT_UYYVYY8_0_5X24)
>>                 venc_freq *= 2;
>>
>>         vclk_freq = max(venc_freq, hdmi_freq);
>> @@ -349,11 +362,11 @@ static void dw_hdmi_set_vclk(struct meson_dw_hdmi *dw_hdmi,
>>         if (mode->flags & DRM_MODE_FLAG_DBLCLK)
>>                 venc_freq /= 2;
>>
>> -       DRM_DEBUG_DRIVER("vclk:%d venc=%d hdmi=%d enci=%d\n",
>> -               vclk_freq, venc_freq, hdmi_freq,
>> +       DRM_DEBUG_DRIVER("vclk:%d phy=%d venc=%d hdmi=%d enci=%d\n",
>> +               phy_freq, vclk_freq, venc_freq, hdmi_freq,
>>                 priv->venc.hdmi_use_enci);
>>
>> -       meson_vclk_setup(priv, MESON_VCLK_TARGET_HDMI, vclk_freq,
>> +       meson_vclk_setup(priv, MESON_VCLK_TARGET_HDMI, phy_freq, vclk_freq,
>>                          venc_freq, hdmi_freq, priv->venc.hdmi_use_enci);
>>  }
>>
>> @@ -386,8 +399,9 @@ 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 Handle the YUV420 case) */
>> -       if (mode->clock > 340000) {
>> +       /* TMDS pattern setup */
>> +       if (mode->clock > 340000 &&
>> +           dw_hdmi->input_bus_format == MEDIA_BUS_FMT_YUV8_1X24) {
>>                 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);
>> @@ -560,6 +574,8 @@ dw_hdmi_mode_valid(struct drm_connector *connector,
>>                    const struct drm_display_mode *mode)
>>  {
>>         struct meson_drm *priv = connector->dev->dev_private;
>> +       bool is_hdmi2_sink = connector->display_info.hdmi.scdc.supported;
>> +       unsigned int phy_freq;
>>         unsigned int vclk_freq;
>>         unsigned int venc_freq;
>>         unsigned int hdmi_freq;
>> @@ -568,8 +584,10 @@ dw_hdmi_mode_valid(struct drm_connector *connector,
>>
>>         DRM_DEBUG_DRIVER("Modeline " DRM_MODE_FMT "\n", DRM_MODE_ARG(mode));
>>
>> -       /* If sink max TMDS clock, we reject the mode */
>> -       if (mode->clock > connector->display_info.max_tmds_clock)
>> +       /* If sink does not support 540MHz, reject the non-420 HDMI2 modes */
>> +       if (mode->clock > connector->display_info.max_tmds_clock &&
>> +           !drm_mode_is_420_only(&connector->display_info, mode) &&
>> +           !drm_mode_is_420_also(&connector->display_info, mode))
>>                 return MODE_BAD;
>>

Hi Maxime,

> 
> This part makes all the modes identified as BAD on my TV, on G12A and
> GXL, which in turn breaks HDMI output (no signal detected).

In fact, the issue comes from patch 2.

+	if (mode->clock > connector->display_info.max_tmds_clock)
+		return MODE_BAD;

is wrong if max_tmds_clock is 0, as reported from a DMT monitor.

The original :
+	/* 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;

was correct, and I was asked to simplify it.

I will submit a fix reverting to the later.

Neil

> 
> Here is the dmesg with drm debug: https://pastebin.com/t3XESC2w
> 
> Cheers,
> Maxime
> 
> |snip]
> 