Re: [RFC 0/8] MIPS: CI20: add HDMI out support

From: Rob Herring <robh@kernel.org>
To: "H. Nikolaus Schaller" <hns@goldelico.com>
Cc: Sam Ravnborg <sam@ravnborg.org>,
	Paul Cercueil <paul@crapouillou.net>,
	Paul Boddie <paul@boddie.org.uk>, David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel@ffwll.ch>,
	Mark Rutland <mark.rutland@arm.com>,
	Ralf Baechle <ralf@linux-mips.org>,
	Paul Burton <paulburton@kernel.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Andi Kleen <ak@linux.intel.com>,
	Krzysztof Kozlowski <krzk@kernel.org>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org, linux-mips@vger.kernel.org,
	linux-gpio@vger.kernel.org, kernel@pyra-handheld.com,
	letux-kernel@openphoenux.org
Subject: Re: [RFC 0/8] MIPS: CI20: add HDMI out support
Date: Tue, 3 Mar 2020 08:58:48 -0600	[thread overview]
Message-ID: <20200303145848.GA13796@bogus> (raw)
In-Reply-To: <8EE60F87-415A-44EA-AA49-632E232095FF@goldelico.com>

On Thu, Feb 27, 2020 at 01:56:56PM +0100, H. Nikolaus Schaller wrote:
> Hi Sam,
> 
> > Am 27.02.2020 um 13:23 schrieb Sam Ravnborg <sam@ravnborg.org>:
> > 
> > Hi Nikolaus.
> > 
> > On Wed, Feb 26, 2020 at 08:12:52PM +0100, H. Nikolaus Schaller wrote:
> >> This patch series adds HDMI output to the jz4780/CI20 board.
> >> 
> >> It is based on taking the old 3.18 vendor kernel and trying
> >> to achieve the same with modern DTS setup and new/modified
> >> drivers.
> >> 
> >> Unfortunately, in this first RFC, only EDID and creation of
> >> /dev/fb0 are working. Also, HDMI hot plugging is detected.
> >> 
> >> But there is no HDMI output signal. So some tiny piece seems
> >> to be missing to enable/configure the Synposys HDMI controller.
> >> 
> >> We need help from the community to fix this.
> >> 
> >> Note: device tree bindings are from 2015 and still seem to
> >> fit - except they are not in yaml format.
> >> 
> >> Original authors of most patches are
> >> * Paul Boddie <paul@boddie.org.uk>
> >> * Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
> >> 
> >> 
> >> H. Nikolaus Schaller (2):
> >>  drm: ingenic-drm: add MODULE_DEVICE_TABLE
> >>  MIPS: CI20: defconfig: configure for DRM_DW_HDMI_JZ4780
> >> 
> >> Paul Boddie (4):
> >>  drm: ingenic: add jz4780 Synopsys HDMI driver.
> >>  pinctrl: ingenic: add hdmi-ddc pin control group
> >>  MIPS: DTS: jz4780: account for Synopsys HDMI driver and LCD controller
> >>  MIPS: DTS: CI20: add HDMI setup
> >> 
> >> Zubair Lutfullah Kakakhel (2):
> >>  dt-bindings: video: Add jz4780-lcd binding
> >>  dt-bindings: video: Add jz4780-hdmi binding
> >> 
> >> .../bindings/display/ingenic-jz4780-hdmi.txt  |  41 ++++++
> >> .../bindings/display/ingenic-jz4780-lcd.txt   |  39 ++++++
> > New bindings in DT Schema format please...
> > We want to have then in a formal launguage so we can use these
> > to verify the DT files.
> 
> Yes, I know. And I fully support the goal.
> 
> But I personally do not have the time to learn the (IMHO brain-twisting)
> way the Schema format is working. Especially, I am not interested
> in becoming volunteer translator for .txt based schemas developed
> by someone else.
> 
> So I hope that someone from the community can and is willing to do
> that.
> 
> Or that there will appear good tools soon. E.g. some GUI
> based editor tool would be very helpful so that you don't have
> to fight with the yaml indentation rules. Like there are XML
> and DTD editors. And even HTML is rarely written manually any more.
> 
> IMHO such tools should have been developed and in place *before*
> the rule to provide DT schemata is enforced.

You mean tools like what is discussed here:

https://www.redhat.com/sysadmin/yaml-tips

There's also yaml-format in the dtschema repo which will reformat a file 
to the desired formatting. It is just a wrapper around ruamel yaml 
library.

Rob