linux-kernel - Re: [PATCH 0/8] drm/meson: Add support for HDMI2.0 4k60

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Message-ID: <20190131164536.GA4674@pendragon.ideasonboard.com>
Date:   Thu, 31 Jan 2019 18:45:36 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Neil Armstrong <narmstrong@...libre.com>
Cc:     a.hajda@...sung.com, Philipp Zabel <p.zabel@...gutronix.de>,
        Sandy Huang <hjc@...k-chips.com>,
        Heiko Stübner <heiko@...ech.de>,
        maxime.ripard@...tlin.com, dri-devel@...ts.freedesktop.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/8] drm/meson: Add support for HDMI2.0 4k60

Hi Neil,

On Thu, Jan 31, 2019 at 02:25:30PM +0100, Neil Armstrong wrote:
> On 15/01/2019 13:33, Neil Armstrong wrote:
> > This patchset aims to add support for the following HDMI2.0 4k60 modes:
> > - 594Mhz TMDS frequency needing TMDS Scramling and 1/40 rate for RGB/YUV4:4:4
> > - 297MHz TMDS frequency with YUV4:2:0 encoding
> > 
> > The first mode uses the SCDC helpers introduced by intel to :
> > - discover where the monitor support SCDC
> > - setup the SCDC parameters
> > This is implemented in the dw-hdmi bridge driver by handling scrambling
> > support during the bridge setup and by exporting an helper for the PHY
> > setup to setup the SCDC configuration for the 1/40 TMDS rate.
> > This code will only be active if the encoder support a TMDS rate > 340MHz.
> > 
> > This patch could eventually break support on different SoC when connected
> > on a 4k60 monitor with SCDC :
> > - i.MX correctly discards pixel clocks > 216MHz
> > - R-CAR discards discards pixel clocks > 297MHz since [1]
> > - Rockchip discards invalid pixel clocks not in the rockchip_mpll_cfg table
> > - sun8i correctly discards pixel clocks > 297MHz on a83t
> > - sun8i discards discards pixel clocks > 594Mhz on h6, which is already broken
> > 
> > First patch should fix support for Allwinner H6.
> > 
> > The second mode is implemented by added the missing 4:2:0 bypass handling
> > in the dw-hdmi bridge driver and adding a "mtmdsclock" separating the
> > pixel clock from the tmds clock in the mode setup phase.
> > We also enable support for these modes in the connector only if the platform
> > glue code explicits the support.
> 
> Do you think patches 1-4 could be applied ?

I would have liked it if there could be a way to avoid exporting
dw_hdmi_set_high_tmds_clock_ratio() in patch 1/8, but if that's not
possible, so be it (I haven't researched that myself). No issue with
patches 2/8 to 4/8.

> Then we could focus on how we manage the bus format between the encoder
> and the bridge ?
> 
> Especially patch 5 linked to patch 7.
> 
> Will one of you be at FOSDEM 2019 ? we could chat about this.

I will be there on Sunday, likely from around 11:00.

> Following subjects on the table will be :
> - HDR metadata transmission aligned with the last patchset sent by intel-gfx
> - Colorspace connector property aligned with the last patchset sent by intel-gfx
> - HDCP 1.4 and 2.2 handling
> 
> > Only the meson DRM dw_hdmi glue allows ycbcr420 modes, so no breakage
> > is expected here.
> > 
> > The remaining patches adds support for :
> > - 1/40 TMDS rate aka DIV40 in the dw-hdmi meson PHY setup
> > - 4:2:0 output and clock setup
> > 
> > The dw-hdmi support re-uses the support done by Rockchip engineers on the
> > Linux 4.4 BSP kernel.
> > 
> > These modes has been validated using a MuxLab HDMI Signal Analyser in
> > addition to different UHD TVs supporting full 4k60 or the 4:2:0 variant.
> > 
> > Changes since RFC v2 at [3]:
> > - Collected tested-by and reviewed-by tags
> > - Changed if condition in "add HDMI div40 TMDS mode"
> > - Updated "Add YUV420 output support" with the same if condition
> > 
> > Changes since RFC v1 at [2]:
> > - Fix all comments from Laurent :
> > - Add define for HDMI 1.4 max tmds clock and SCDC supported version
> > - Call dw_hdmi_set_high_tmds_clock_ratio() in dw_hdmi_phy_enable_powerdown()
> > to unbreak Allwinner H6
> > - Pass in_t(u8, bytes, SCDC_MIN_SOURCE_VERSION) as SCDC version
> > - Finally add comments for SCDC and Scrambling process
> > 
> > [1] https://patchwork.freedesktop.org/patch/263616/
> > [2] https://patchwork.freedesktop.org/series/52950/#rev1
> > [3] https://patchwork.freedesktop.org/series/52950/#rev2
> > 
> > Neil Armstrong (7):
> >   drm/bridge: dw-hdmi: Add SCDC and TMDS Scrambling support
> >   drm/meson: add HDMI div40 TMDS mode
> >   drm/meson: add support for HDMI2.0 2160p modes
> >   drm/bridge: dw-hdmi: add support for YUV420 output
> >   drm/bridge: dw-hdmi: allow ycbcr420 modes for >= 0x200a
> >   drm/meson: Add YUV420 output support
> >   drm/meson: Output in YUV444 if sink supports it
> > 
> > Zheng Yang (1):
> >   drm/bridge: dw-hdmi: support dynamically get input/out color info
> > 
> >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 182 +++++++++++++++++++---
> >  drivers/gpu/drm/bridge/synopsys/dw-hdmi.h |   1 +
> >  drivers/gpu/drm/meson/meson_dw_hdmi.c     | 128 ++++++++++++---
> >  drivers/gpu/drm/meson/meson_vclk.c        |  93 ++++++++---
> >  drivers/gpu/drm/meson/meson_vclk.h        |   7 +-
> >  drivers/gpu/drm/meson/meson_venc.c        |   8 +-
> >  drivers/gpu/drm/meson/meson_venc.h        |  11 ++
> >  drivers/gpu/drm/meson/meson_venc_cvbs.c   |   3 +-
> >  include/drm/bridge/dw_hdmi.h              |   7 +
> >  9 files changed, 374 insertions(+), 66 deletions(-)

-- 
Regards,

Laurent Pinchart