From: Maxime Ripard <maxime.ripard@bootlin.com>
To: Chen-Yu Tsai <wens@csie.org>
Cc: "Jernej Škrabec" <jernej.skrabec@siol.net>,
"Rob Herring" <robh+dt@kernel.org>,
"David Airlie" <airlied@linux.ie>,
"Gustavo Padovan" <gustavo@padovan.org>,
"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
"Sean Paul" <seanpaul@chromium.org>,
"Mark Rutland" <mark.rutland@arm.com>,
dri-devel <dri-devel@lists.freedesktop.org>,
devicetree <devicetree@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
linux-clk <linux-clk@vger.kernel.org>,
linux-sunxi <linux-sunxi@googlegroups.com>
Subject: Re: [linux-sunxi] Re: [PATCH v3 09/24] drm/sun4i: Don't skip TCONs if they don't have channel 0
Date: Thu, 5 Jul 2018 09:03:58 +0200 [thread overview]
Message-ID: <20180705070358.7ng4shuo3pxp62q6@flea> (raw)
In-Reply-To: <CAGb2v66_6RoYk6MRtTJeqg0Z09A7y+pvSxs7qeeND+iKPE_+BA@mail.gmail.com>
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On Sun, Jul 01, 2018 at 11:11:06PM +0800, Chen-Yu Tsai wrote:
> On Sun, Jul 1, 2018 at 4:27 PM, Jernej Škrabec <jernej.skrabec@siol.net> wrote:
> > Dne četrtek, 28. junij 2018 ob 08:24:34 CEST je Chen-Yu Tsai napisal(a):
> >> On Thu, Jun 28, 2018 at 12:45 PM, Jernej Škrabec
> >>
> >> <jernej.skrabec@siol.net> wrote:
> >> > Dne četrtek, 28. junij 2018 ob 03:51:31 CEST je Chen-Yu Tsai napisal(a):
> >> >> On Mon, Jun 25, 2018 at 8:02 PM, Jernej Skrabec <jernej.skrabec@siol.net>
> >> >
> >> > wrote:
> >> >> > TV TCONs (channel 1 only) are always connected to TV or HDMI encoder.
> >> >> > Because of that, all output endpoints on such TCON node will point to a
> >> >> > encoder which is part of component framework.
> >> >> >
> >> >> > Correct current graph traversing algorithm in such way that it doesn't
> >> >> > skip output enpoints with id 0 on TV TCONs.
> >> >>
> >> >> No. Our bindings say that endpoint 0 _is_ channel 0. For TCONs that don't
> >> >> have channel 0, it must be skipped.
> >> >
> >> > I'm not sure where this is stated. I read TCON binding again. Can you
> >> > please point me to it?
> >>
> >> https://elixir.bootlin.com/linux/latest/source/Documentation/devicetree/bind
> >> ings/display/sunxi/sun4i-drm.txt#L169
> >>
> >> Our TCON driver still expects RGB or LVDS panel / bridges on endpoint 0.
> >
> > Yes, but that can only happen on TCON which has channel 0. TV TCONs (those
> > with channel 1 only) can't have panels or bridges connected to them, because
> > they are internally always connected to either HDMI or TV encoder or both.
> > Actually, R40 is the only SoC, where same TV TCON can be connected to TV
> > encoder or HDMI. Others have specialized TV TCONs, which are connect to only
> > one encoder.
> >
> > IMO TV TCONs are really just stripped down LCD TCONs to support one (or max
> > two) specific encoder.
>
> I agree. We've seen these first in the H3, and the reverse, TCONs only with
> LCD, on the A23/A33.
>
> >> So I guess this was sort of implied historically. It's no longer true.
> >> This is something we should probably fix.
> >
> > Fixed in what way? You mean update bindings to mention that TCON output
> > endpoint 0 is reserved for panels or bridges?
>
> Either that, or have the drm driver look at other endpoints. I guess we
> should ask Maxime if this is already done or not, since the DSI driver
> isn't endpoint 0 in the A33 dtsi.
The DSI driver isn't really a good example for this, since the panel
isn't described as part of the OF graph, but DSI binding require that
it's a child of the DSI controller node.
> >>
> >> In practice our drivers don't look at it (yet), but rely on the downstream
> >> encoder type to determine which channel to use.
> >>
> >> But please add the "allwinner,tcon-channel" property as specified in
> >> the binding.
> >
> > It's my understanding of TCON binding documentation that property
> > "allwinner,tcon-channel" is needed only if TCON supports both channels. TV
> > TCON clearly supports only channel 1. In that case, there is no doubt to which
> > channel output endpoint belongs.
> >
> > If that's not true, dt bindings documentation should be reworded to contain
> > word "needed" or something similar. Currently, no DT for newer SoC contains
> > that property (for example, A83T, H3, H5 or even A33).
Yeah, but that's mainly because we have a single output enabled for
each channel on those newer SoCs. When / if we enable the RGB and LVDS
output for example, we will have to set this.
> > On A33 this is even more interesting, since tcon0 has only channel
> > 0 and has DSI output endpoint with number 1. According to TCON
> > binding docs, if "allwinner,tcon-channel" is not preset, endpoint
> > number represent channel. So, that would mean DSI needs channel 1
> > on tcon which supports clearly only channel 0. So either there
> > TCON bindings documentation needs updates or DT for A33 has to be
> > updated.
>
> Maxime? You did the A33 DSI stuff.
I guess it's missing on the A33 DSI endpoint.
Maxime
--
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com
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next prev parent reply other threads:[~2018-07-05 7:04 UTC|newest]
Thread overview: 87+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-25 12:02 [PATCH v3 00/24] Add support for R40 HDMI pipeline Jernej Skrabec
2018-06-25 12:02 ` [PATCH v3 01/24] clk: sunxi-ng: r40: Add minimal rate for video PLLs Jernej Skrabec
2018-06-25 12:02 ` [PATCH v3 02/24] clk: sunxi-ng: r40: Allow setting parent rate to display related clocks Jernej Skrabec
2018-06-25 12:02 ` [PATCH v3 03/24] clk: sunxi-ng: r40: Export video PLLs Jernej Skrabec
2018-06-25 12:30 ` Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 04/24] dt-bindings: display: sunxi-drm: Add TCON TOP description Jernej Skrabec
2018-06-25 17:33 ` Rob Herring
2018-06-25 12:02 ` [PATCH v3 05/24] drm/sun4i: Add TCON TOP driver Jernej Skrabec
2018-06-28 1:47 ` Chen-Yu Tsai
2018-06-29 19:09 ` Jernej Škrabec
2018-06-30 1:13 ` [linux-sunxi] " Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 06/24] drm/sun4i: Fix releasing node when enumerating enpoints Jernej Skrabec
2018-06-28 1:53 ` [linux-sunxi] " Chen-Yu Tsai
2018-06-29 19:15 ` Jernej Škrabec
2018-06-30 1:09 ` Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 07/24] drm/sun4i: Split out code for enumerating endpoints in output port Jernej Skrabec
2018-06-28 1:57 ` [linux-sunxi] " Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 08/24] drm/sun4i: Add support for traversing graph with TCON TOP Jernej Skrabec
2018-06-28 1:57 ` Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 09/24] drm/sun4i: Don't skip TCONs if they don't have channel 0 Jernej Skrabec
2018-06-28 1:51 ` Chen-Yu Tsai
2018-06-28 4:45 ` Jernej Škrabec
2018-06-28 6:24 ` [linux-sunxi] " Chen-Yu Tsai
2018-07-01 8:27 ` Jernej Škrabec
2018-07-01 15:11 ` Chen-Yu Tsai
2018-07-05 7:03 ` Maxime Ripard [this message]
2018-07-05 20:03 ` Jernej Škrabec
2018-07-09 8:59 ` Maxime Ripard
2018-06-25 12:02 ` [PATCH v3 10/24] drm/sun4i: tcon: Generalize engine search algorithm Jernej Skrabec
2018-06-28 2:06 ` Chen-Yu Tsai
2018-06-28 4:48 ` Jernej Škrabec
2018-06-28 18:25 ` Maxime Ripard
2018-06-29 19:06 ` Jernej Škrabec
2018-07-01 19:09 ` [linux-sunxi] " Jernej Škrabec
2018-07-02 8:56 ` Maxime Ripard
2018-06-25 12:02 ` [PATCH v3 11/24] drm/sun4i: Don't check for LVDS and RGB when TCON has only ch1 Jernej Skrabec
2018-06-28 2:08 ` Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 12/24] drm/sun4i: Don't check for panel or bridge on TV TCONs Jernej Skrabec
2018-06-28 2:17 ` Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 13/24] dt-bindings: display: sun4i-drm: Add R40 mixer compatibles Jernej Skrabec
2018-06-28 2:17 ` Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 14/24] drm/sun4i: Add support for R40 mixers Jernej Skrabec
2018-06-28 2:18 ` Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 15/24] dt-bindings: display: sun4i-drm: Add description of A64 HDMI PHY Jernej Skrabec
2018-06-28 2:19 ` Chen-Yu Tsai
2018-06-28 4:51 ` Jernej Škrabec
2018-06-28 7:00 ` [linux-sunxi] " Chen-Yu Tsai
2018-06-29 19:32 ` Jernej Škrabec
2018-07-04 4:05 ` Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 16/24] drm/sun4i: Enable DW HDMI PHY clock Jernej Skrabec
2018-06-28 2:22 ` Chen-Yu Tsai
2018-06-28 4:52 ` Jernej Škrabec
2018-06-29 19:19 ` Jernej Škrabec
2018-06-30 1:11 ` Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 17/24] drm/sun4i: Don't change clock bits in DW HDMI PHY driver Jernej Skrabec
2018-06-28 2:24 ` Chen-Yu Tsai
2018-06-29 19:23 ` Jernej Škrabec
2018-06-25 12:02 ` [PATCH v3 18/24] drm/sun4i: DW HDMI PHY: Add support for second PLL Jernej Skrabec
2018-06-28 2:25 ` Chen-Yu Tsai
2018-06-28 4:56 ` Jernej Škrabec
2018-06-28 6:59 ` [linux-sunxi] " Chen-Yu Tsai
2018-06-25 12:02 ` [PATCH v3 19/24] drm/sun4i: Add support for second clock parent to DW HDMI PHY clk driver Jernej Skrabec
2018-06-28 2:30 ` [linux-sunxi] " Chen-Yu Tsai
2018-06-25 12:03 ` [PATCH v3 20/24] drm/sun4i: Add support for A64 HDMI PHY Jernej Skrabec
2018-06-28 2:30 ` Chen-Yu Tsai
2018-06-25 12:03 ` [PATCH v3 21/24] drm: of: Export drm_crtc_port_mask() Jernej Skrabec
2018-06-28 2:32 ` Chen-Yu Tsai
2018-06-25 12:03 ` [PATCH v3 22/24] drm/sun4i: DW HDMI: Expand algorithm for possible crtcs Jernej Skrabec
2018-06-28 2:42 ` Chen-Yu Tsai
2018-06-25 12:03 ` [PATCH v3 23/24] ARM: dts: sun8i: r40: Add HDMI pipeline Jernej Skrabec
2018-06-28 2:50 ` Chen-Yu Tsai
2018-06-28 5:15 ` Jernej Škrabec
2018-06-28 6:51 ` [linux-sunxi] " Chen-Yu Tsai
2018-07-01 10:41 ` Jernej Škrabec
2018-07-01 13:52 ` Chen-Yu Tsai
2018-07-01 15:13 ` Jernej Škrabec
2018-07-01 15:35 ` Chen-Yu Tsai
2018-07-01 19:25 ` Jernej Škrabec
2018-07-02 21:39 ` Jernej Škrabec
2018-06-25 12:03 ` [PATCH v3 24/24] ARM: dts: sun8i: r40: Enable HDMI output on BananaPi M2 Ultra Jernej Skrabec
2018-06-28 2:51 ` [linux-sunxi] " Chen-Yu Tsai
2018-06-25 12:07 ` [linux-sunxi] [PATCH v3 00/24] Add support for R40 HDMI pipeline Jernej Škrabec
2018-06-25 16:43 ` Maxime Ripard
2018-06-27 18:02 ` Maxime Ripard
2018-06-27 19:50 ` Maxime Ripard
2018-06-27 20:25 ` Jernej Škrabec
2018-06-28 8:41 ` Maxime Ripard
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