* Re: [PATCH 0/9] Doc/DT: DT bindings for various display components
From: Philipp Zabel @ 2014-02-28 13:47 UTC (permalink / raw)
To: Sebastian Hesselbarth
Cc: devicetree, linux-fbdev, Russell King - ARM Linux, dri-devel,
Andrzej Hajda, Tomi Valkeinen, Laurent Pinchart, linux-arm-kernel
In-Reply-To: <531087C0.1090501@gmail.com>
Hi,
Am Freitag, den 28.02.2014, 13:57 +0100 schrieb Sebastian Hesselbarth:
> On 02/28/14 13:20, Tomi Valkeinen wrote:
> > This series is a re-send of
> > http://article.gmane.org/gmane.linux.drivers.devicetree/61739
> >
> ...
> > Shortly about the display components in the series, in the order of probable
> > public interest:
> >
> > * Analog TV, DVI and HDMI Connectors represent a respective connector on the
> > board. They don't do much, but they do mark the end of the video pipeline (from
> > the board's pov), and they should also in the future offer ways to handle
> > things like the +5V pin on DVI and HDMI connector and HPD pin.
> >
> > * MIPI DPI panel and MIPI DSI CM panels represent bindings for simple panels
> > using the respective video bus.
> >
> > * Sony acx565akm is an SPI controlled panel using flatlink video bus.
> >
> > * TFP410 is a DPI to DVI encoder.
> >
> > * TPD12S015 is a HDMI companion chip, used on OMAP boards.
>
> Tomi,
>
> Out of curiosity, will there be DT nodes for pull-up resistors soon,
> too? ;)
>
> Honestly, TPD12S015 is a level shifter, there is nothing in it that
> would justify a DT node nor a driver.
>
> Above you already note, that connector nodes should offer HPD in the
> future, but I guess the binding should represent that now already.
> I will be a DT stub anyway, the corresponding video sink driver will
> have to look it up.
>
> Looking through the bindings for DVI and HDMI, I guess HPD gpio is
> better kept in those nodes. From the relevant (DT) properties DVI and
> HDMI connectors are in no way different.
I like the idea of adding actual connector nodes to the board device
trees. A TV encoder driver for example could this way detect from the
device tree whether it is connected to a VGA, Composite, or S-Video
connector (or maybe to both Composite and S-Video connectors at the same
time).
regards
Philipp
^ permalink raw reply
* Re: [PATCH 0/9] Doc/DT: DT bindings for various display components
From: Sebastian Hesselbarth @ 2014-02-28 13:51 UTC (permalink / raw)
To: Tomi Valkeinen, linux-fbdev-u79uwXL29TY76Z2rM5mHXA,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r
Cc: Philipp Zabel, Laurent Pinchart, Russell King - ARM Linux,
Sascha Hauer, Rob Clark, Inki Dae, Andrzej Hajda, Tomasz Figa,
Thierry Reding
In-Reply-To: <53108B9C.5000006-l0cyMroinI0@public.gmane.org>
On 02/28/14 14:14, Tomi Valkeinen wrote:
> On 28/02/14 14:57, Sebastian Hesselbarth wrote:
>
>> Out of curiosity, will there be DT nodes for pull-up resistors soon,
>> too? ;)
>
> If they don't work automatically, yes, we need DT nodes and drivers for
> them.
>
>> Honestly, TPD12S015 is a level shifter, there is nothing in it that
>> would justify a DT node nor a driver.
>
> TPD requires a power. Who turns that on? It also has two GPIOs, LS_OE
> and CT_CP_HPD, which need to be controlled based on what the user wants
> and the state of the HPD line. Who controls those?
Strictly speaking TPD12S015 has _no_ GPIO but only buffers. It
translates one voltage to another. The controlling instance is
your "video card" that is really interested in the actual state
of HPD signal.
Also the same for power, TPD12S015 doesn't decide to be powered up
or down but the "video card" does. We have GPIO regulators that
deal with that situation already.
Consider the same board but replace TPD12S015 with another level-
shifter, you still want OMAP video driver work with that out-of-the-box,
don't you? Fact is, OMAP IP requires GPIOs to sense HPD status hence
that GPIO is a property of the corresponding OMAP node. How level-
translation happens is irrelevant here.
>> Above you already note, that connector nodes should offer HPD in the
>> future, but I guess the binding should represent that now already.
>
> I think it can be added when somebody uses it. I don't see why that
> would cause trouble later to those that don't use it.
Thinking about it again, HPD gpio shouldn't be a property of the
connector at all but again the controlling instance. The connector
cannot deal with the information provided by HPD nor can it determine
if anyone is listening to HPD events.
>> I will be a DT stub anyway, the corresponding video sink driver will
>> have to look it up.
>
> I'm not sure what you mean with that. Yes, it's not the most complex DT
> nodes out there.
>
>> Looking through the bindings for DVI and HDMI, I guess HPD gpio is
>> better kept in those nodes. From the relevant (DT) properties DVI and
>> HDMI connectors are in no way different.
>
> Well, I think the HPD gpio should be where it's most logical to have it.
Right, but this is usually the controlling instance and not the
consuming one. E.g. to detect presence of an MMC card by GPIO, you'd
put that into the MMC _controller_ not any card node.
> I mean, you could have a setup where you have the SoC HDMI encoder and
> and the HDMI connector, and the HPD pin goes directly to the HDMI
> encoder, which has HW support for it. In that case, the HDMI encoder
> node should contain the HPD, and the HDMI encoder should handle it.
I wonder, if in case of an dedicated HPD pin, you would ever expose that
in DT.
> Or, your HDMI encoder could not have any kind of support for HPD. In
> that case you could have the HDMI connector driver handle the hotplug
> event. You could of course make the HDMI encoder driver handle the HPD
> gpio, but I usually try to have the driver handle the hardware device in
> question.
Having a driver for a dumb connector seems to be a little exaggerated.
Consider your generic HDMI connector "driver" connected to dedicated HPD
case above. It is pretty useless then. OTOH video controllers with
dedicated HPD know very well they can control HPD themselves, video
controllers without dedicated HPD also know very well that they need
GPIO for it.
> In OMAP's case, we have the TPD chip between the HDMI encoder and the
> connector, and the logical place to handle HPD GPIO in that case is the
> TPD driver, as that's where the HPD is connected to and the TPD needs to
> be configured according to the state of the HPD.
Is it really the logical place to handle HPD? I'd have put it into the
HDMI encoder because it's the unit most interested in the state of HPD.
Please, don't get me wrong, I like all this to be baked into a binding -
just wondering if a level-shifter driver plus corresponding DT node
is too much detail in here.
Sebastian
^ permalink raw reply
* Re: [PATCH 0/9] Doc/DT: DT bindings for various display components
From: Sebastian Hesselbarth @ 2014-02-28 13:56 UTC (permalink / raw)
To: Philipp Zabel
Cc: Tomi Valkeinen, linux-fbdev-u79uwXL29TY76Z2rM5mHXA,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
Laurent Pinchart, Russell King - ARM Linux, Sascha Hauer,
Rob Clark, Inki Dae, Andrzej Hajda, Tomasz Figa, Thierry Reding
In-Reply-To: <1393595264.3802.39.camel-+qGW7pzALmz7o/J7KWpOmN53zsg1cpMQ@public.gmane.org>
On 02/28/14 14:47, Philipp Zabel wrote:
> Am Freitag, den 28.02.2014, 13:57 +0100 schrieb Sebastian Hesselbarth:
>> On 02/28/14 13:20, Tomi Valkeinen wrote:
>>> This series is a re-send of
>>> http://article.gmane.org/gmane.linux.drivers.devicetree/61739
>>>
>> ...
>>> Shortly about the display components in the series, in the order of probable
>>> public interest:
>>>
>>> * Analog TV, DVI and HDMI Connectors represent a respective connector on the
>>> board. They don't do much, but they do mark the end of the video pipeline (from
>>> the board's pov), and they should also in the future offer ways to handle
>>> things like the +5V pin on DVI and HDMI connector and HPD pin.
>>>
>>> * MIPI DPI panel and MIPI DSI CM panels represent bindings for simple panels
>>> using the respective video bus.
>>>
>>> * Sony acx565akm is an SPI controlled panel using flatlink video bus.
>>>
>>> * TFP410 is a DPI to DVI encoder.
>>>
>>> * TPD12S015 is a HDMI companion chip, used on OMAP boards.
>>
>> Tomi,
>>
>> Out of curiosity, will there be DT nodes for pull-up resistors soon,
>> too? ;)
>>
>> Honestly, TPD12S015 is a level shifter, there is nothing in it that
>> would justify a DT node nor a driver.
>>
>> Above you already note, that connector nodes should offer HPD in the
>> future, but I guess the binding should represent that now already.
>> I will be a DT stub anyway, the corresponding video sink driver will
>> have to look it up.
>>
>> Looking through the bindings for DVI and HDMI, I guess HPD gpio is
>> better kept in those nodes. From the relevant (DT) properties DVI and
>> HDMI connectors are in no way different.
>
> I like the idea of adding actual connector nodes to the board device
> trees. A TV encoder driver for example could this way detect from the
> device tree whether it is connected to a VGA, Composite, or S-Video
> connector (or maybe to both Composite and S-Video connectors at the same
> time).
I agree that different connectors help providing a better
user-experienced view of board layout. But I doubt that besides the
differentiation (HDMI, DVI, VGA, SVideo, ...) and the endpoint there
should be anything more in that node.
Sebastian
^ permalink raw reply
* Re: [PATCH 0/9] Doc/DT: DT bindings for various display components
From: Tomi Valkeinen @ 2014-02-28 15:39 UTC (permalink / raw)
To: Sebastian Hesselbarth, linux-fbdev, dri-devel, devicetree,
linux-arm-kernel
Cc: Russell King - ARM Linux, Sascha Hauer, Tomasz Figa, Inki Dae,
Andrzej Hajda, Rob Clark, Thierry Reding, Laurent Pinchart,
Philipp Zabel
In-Reply-To: <5310945A.9040106@gmail.com>
[-- Attachment #1: Type: text/plain, Size: 8208 bytes --]
On 28/02/14 15:51, Sebastian Hesselbarth wrote:
>> TPD requires a power. Who turns that on? It also has two GPIOs, LS_OE
>> and CT_CP_HPD, which need to be controlled based on what the user wants
>> and the state of the HPD line. Who controls those?
>
> Strictly speaking TPD12S015 has _no_ GPIO but only buffers. It
What do you mean with that? That TPD doesn't provide GPIOs that you
could control, in the sense that SoCs do? Sure. I didn't mean that. I
meant it has gpios in the same sense that, say, a panel might have a
'enable' gpio.
Somebody needs to control the gpio state. For a panel, I would say it's
the panel driver's job. And the gpio would be present in the panel's DT
node. The same way for TDP.
> translates one voltage to another. The controlling instance is
> your "video card" that is really interested in the actual state
> of HPD signal.
Well. I think it's the driver for the respective hardware device that
handles the gpio. Of course, that driver will usually get information
from somewhere else when to use those gpios. It may be the "video card",
but really, the video card driver also gets the information if to enable
the output from somewhere else.
> Also the same for power, TPD12S015 doesn't decide to be powered up
> or down but the "video card" does. We have GPIO regulators that
> deal with that situation already.
The same here. TPD driver gets told to enable itself (or some particular
feature that it supports). It will then enable the required powers.
> Consider the same board but replace TPD12S015 with another level-
> shifter, you still want OMAP video driver work with that out-of-the-box,
Right. For this exact reason, the TPD is a separate driver. I can easily
leave it out, or replace it with any other similar chip. Or the TPD
driver can be used on some other platform.
OMAP video driver doesn't know anything about TPD, as TPD is not part of
OMAP video hardware, or even OMAP SoC.
How would this work without TPD, or with, say, TPD1234567, which instead
has 5 GPIOs that need to be set in particular order? The video card
driver would need to know the exact details of all possible level
shifters out there? Or?
> don't you? Fact is, OMAP IP requires GPIOs to sense HPD status hence
> that GPIO is a property of the corresponding OMAP node. How level-
> translation happens is irrelevant here.
No it doesn't. There are different ways to handle HPD on OMAP HDMI. It's
true that the HDMI IP supports directly handling HPD, but that's not
used as there were some issues with it (I don't remember what). The HPD
can as well be handled outside the HDMI driver.
If the HDMI IP would be handling the HPD, then, yes, HDMI node would
have HPD gpio defined.
> Thinking about it again, HPD gpio shouldn't be a property of the
> connector at all but again the controlling instance. The connector
> cannot deal with the information provided by HPD nor can it determine
> if anyone is listening to HPD events.
Well, this goes into the driver implementation details, but I disagree.
You have a video pipeline, let's say it's just SoC's HDMI encoder, and
HDMI connector. In this particular case, the HDMI encoder IP has no
support for HPD. On top of that, you have a "video card" driver,
"display subsystem" driver, or whatever you want to call it, which is in
control of the video pipeline. Let's call it controller.
The controller asks to get notified of a HPD event from the video
pipeline. It doesn't care if the HPD is handled by the HDMI encoder
driver or the connector driver. They can each handle it, in ways that
suit the particular hardware they control. Of course, handling it in
only one place usually makes sense.
When the controller is notified of a HPD, it can then decide what to do.
If the user has told it to enable video output on HPD, the controller
can command the video pipeline to be enabled.
>> Well, I think the HPD gpio should be where it's most logical to have it.
>
> Right, but this is usually the controlling instance and not the
> consuming one. E.g. to detect presence of an MMC card by GPIO, you'd
> put that into the MMC _controller_ not any card node.
I'm not familiar with MMC, so there it may be clear. With video, we can
have arbitrarily long video pipeline chains, with each component changed
to some other, differently behaving component.
Let's think of another case. SoC's DSI encoder, an external HDMI
encoder, and a HDMI connector. Who handles the HPD? Surely not the SoC's
DSI encoder, as there's no such concept as HPD in DSI? The "video card"
driver? Maybe, but from the video card's perspective, it is driving a
DSI peripheral, and again no HPD in DSI.
The logical place there is the external HDMI encoder. And again, the
HDMI encoder doesn't independently handle decisions about what to do
when HPD happens. It just catches it, and tells somebody wiser about it.
And really, what's the difference with, say, an external HDMI encoder
and TPD? Ok, lots =). But they both take video input in, output video,
and require some config/control to make the chip work.
I totally agree that TPD is on the simpler side of components. But I
think it fits right in into the model, and it works great on OMAP.
Compared to older version, where TPD support was baked into the OMAP
HDMI driver, which was a mess.
>> I mean, you could have a setup where you have the SoC HDMI encoder and
>> and the HDMI connector, and the HPD pin goes directly to the HDMI
>> encoder, which has HW support for it. In that case, the HDMI encoder
>> node should contain the HPD, and the HDMI encoder should handle it.
>
> I wonder, if in case of an dedicated HPD pin, you would ever expose that
> in DT.
Yes, if it's a dedicated pin, no configuration information needed, thus
no information needed in DT. Well, pinctrl maybe.
> Having a driver for a dumb connector seems to be a little exaggerated.
> Consider your generic HDMI connector "driver" connected to dedicated HPD
> case above. It is pretty useless then. OTOH video controllers with
> dedicated HPD know very well they can control HPD themselves, video
> controllers without dedicated HPD also know very well that they need
> GPIO for it.
Yes, I have to say I'm not 100% sure about the connectors. They could
perhaps be left out. But they make things consistent, in my opinion, as
they present a terminator for the video pipeline.
Say, you could have these two different boards:
SoC HDMI -> TPD -> HDMI connector
SoC HDMI -> TPD -> Embedded HDMI panel
In both cases, there's a component at the end, which is the end of the
pipeline (as far as we're concerned). I think it makes the driver side a
bit cleaner, and doesn't leave the TPD's output "hanging out" there.
Also I have used the connector drivers for actual work. The DVI
connector has support for reading EDID via i2c. This is again something
that you can argue that, hey, it should be the "video card" doing it.
But it fits quite well into the DVI connector, and there's no other
hardware component that has any support for the EDID.
I again see the above so that the video pipeline offers a way to read
EDID. Where exactly that's done and how it happens on the hardware
level, the controller doesn't care.
>> In OMAP's case, we have the TPD chip between the HDMI encoder and the
>> connector, and the logical place to handle HPD GPIO in that case is the
>> TPD driver, as that's where the HPD is connected to and the TPD needs to
>> be configured according to the state of the HPD.
>
> Is it really the logical place to handle HPD? I'd have put it into the
> HDMI encoder because it's the unit most interested in the state of HPD.
At least in OMAP's case, when not using the HDMI encoder's support for
HPD, the HDMI encoder is not interested at all about the HPD.
> Please, don't get me wrong, I like all this to be baked into a binding -
> just wondering if a level-shifter driver plus corresponding DT node
> is too much detail in here.
Thanks for the comments, I appreciate it. I hope I've convinced you
enough =).
Tomi
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 901 bytes --]
^ permalink raw reply
* Re: [PATCH 3/9] Doc/DT: Add DT binding documentation for DVI Connector
From: Russell King - ARM Linux @ 2014-02-28 15:59 UTC (permalink / raw)
To: Tomi Valkeinen
Cc: linux-fbdev-u79uwXL29TY76Z2rM5mHXA,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r, Philipp Zabel,
Laurent Pinchart, Sascha Hauer, Sebastian Hesselbarth, Rob Clark,
Inki Dae, Andrzej Hajda, Tomasz Figa, Thierry Reding
In-Reply-To: <1393590016-9361-4-git-send-email-tomi.valkeinen-l0cyMroinI0@public.gmane.org>
On Fri, Feb 28, 2014 at 02:20:10PM +0200, Tomi Valkeinen wrote:
> Add DT binding documentation for DVI Connector.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Reviewed-by: Archit Taneja <archit@ti.com>
> ---
> .../devicetree/bindings/video/dvi-connector.txt | 26 ++++++++++++++++++++++
> 1 file changed, 26 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/video/dvi-connector.txt
>
> diff --git a/Documentation/devicetree/bindings/video/dvi-connector.txt b/Documentation/devicetree/bindings/video/dvi-connector.txt
> new file mode 100644
> index 000000000000..6a0aff866c78
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/video/dvi-connector.txt
> @@ -0,0 +1,26 @@
> +DVI Connector
> +=======
> +
> +Required properties:
> +- compatible: "dvi-connector"
> +
> +Optional properties:
> +- label: a symbolic name for the connector
> +- i2c-bus: phandle to the i2c bus that is connected to DVI DDC
> +
> +Required nodes:
> +- Video port for DVI input
> +
> +Example
> +-------
> +
> +dvi0: connector@0 {
> + compatible = "dvi-connector";
> + label = "dvi";
> +
> + i2c-bus = <&i2c3>;
> +
> + dvi_connector_in: endpoint {
> + remote-endpoint = <&tfp410_out>;
> + };
> +};
This looks far too simplistic. There are different classes of DVI
connector - there is:
DVI A - analogue only
DVI D - digital only (single and dual link)
DVI I - both (single and dual digital link)
DRM at least makes a distinction between these three classes, and this
disctinction is part of the user API. How would a display system know
which kind of DVI connector is wired up on the board from this DT
description?
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
^ permalink raw reply
* Re: [PATCH 4/9] Doc/DT: Add DT binding documentation for HDMI Connector
From: Russell King - ARM Linux @ 2014-02-28 16:06 UTC (permalink / raw)
To: Tomi Valkeinen
Cc: devicetree, linux-fbdev, dri-devel, Andrzej Hajda,
Laurent Pinchart, linux-arm-kernel, Sebastian Hesselbarth
In-Reply-To: <1393590016-9361-5-git-send-email-tomi.valkeinen@ti.com>
On Fri, Feb 28, 2014 at 02:20:11PM +0200, Tomi Valkeinen wrote:
> Add DT binding documentation for HDMI Connector.
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Reviewed-by: Archit Taneja <archit@ti.com>
> ---
> .../devicetree/bindings/video/hdmi-connector.txt | 23 ++++++++++++++++++++++
> 1 file changed, 23 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/video/hdmi-connector.txt
>
> diff --git a/Documentation/devicetree/bindings/video/hdmi-connector.txt b/Documentation/devicetree/bindings/video/hdmi-connector.txt
> new file mode 100644
> index 000000000000..5d25f6a432bb
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/video/hdmi-connector.txt
> @@ -0,0 +1,23 @@
> +HDMI Connector
> +=======
> +
> +Required properties:
> +- compatible: "hdmi-connector"
> +
> +Optional properties:
> +- label: a symbolic name for the connector
> +
> +Required nodes:
> +- Video port for HDMI input
> +
> +Example
> +-------
> +
> +hdmi0: connector@1 {
> + compatible = "hdmi-connector";
> + label = "hdmi";
> +
> + hdmi_connector_in: endpoint {
> + remote-endpoint = <&tpd12s015_out>;
> + };
> +};
It seems rather weird to have DVI connectors having an optional I2C
property, but HDMI (which augments DVI) not having that as at least an
optional property.
I can quite well see the iMX HDMI support needing an i2c bus here.
Also, HDMI has two connector standards - type A and type B, much like
the single vs dual link of DVI. Again, DRM exposes this to userspace.
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
^ permalink raw reply
* Re: [PATCH 3/9] Doc/DT: Add DT binding documentation for DVI Connector
From: Tomi Valkeinen @ 2014-02-28 16:12 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: devicetree, linux-fbdev, Sascha Hauer, Tomasz Figa, dri-devel,
Inki Dae, Andrzej Hajda, Rob Clark, Thierry Reding,
Laurent Pinchart, Philipp Zabel, linux-arm-kernel,
Sebastian Hesselbarth
In-Reply-To: <20140228155937.GQ21483@n2100.arm.linux.org.uk>
[-- Attachment #1: Type: text/plain, Size: 1094 bytes --]
On 28/02/14 17:59, Russell King - ARM Linux wrote:
>> +dvi0: connector@0 {
>> + compatible = "dvi-connector";
>> + label = "dvi";
>> +
>> + i2c-bus = <&i2c3>;
>> +
>> + dvi_connector_in: endpoint {
>> + remote-endpoint = <&tfp410_out>;
>> + };
>> +};
>
> This looks far too simplistic. There are different classes of DVI
> connector - there is:
>
> DVI A - analogue only
> DVI D - digital only (single and dual link)
> DVI I - both (single and dual digital link)
>
> DRM at least makes a distinction between these three classes, and this
> disctinction is part of the user API. How would a display system know
> which kind of DVI connector is wired up on the board from this DT
> description?
Yes, I think that's a valid change. But do we also need to specify
single/dual link, in addition to the three types?
I guess the compatible string is the easiest way for differentation, at
least for the three main types, i.e. "dvi-d-connector" etc.
"dvi-d-1l-connector" and "dvi-d-2l-connector" for the single/dual link?
That looks a bit funny.
Tomi
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 901 bytes --]
^ permalink raw reply
* Re: [PATCH 9/9] Doc/DT: Add DT binding documentation for tpd12s015 encoder
From: Russell King - ARM Linux @ 2014-02-28 16:13 UTC (permalink / raw)
To: Tomi Valkeinen
Cc: linux-fbdev-u79uwXL29TY76Z2rM5mHXA,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r, Philipp Zabel,
Laurent Pinchart, Sascha Hauer, Sebastian Hesselbarth, Rob Clark,
Inki Dae, Andrzej Hajda, Tomasz Figa, Thierry Reding
In-Reply-To: <1393590016-9361-10-git-send-email-tomi.valkeinen-l0cyMroinI0@public.gmane.org>
On Fri, Feb 28, 2014 at 02:20:16PM +0200, Tomi Valkeinen wrote:
> Add DT binding documentation for tpd12s015 encoder
>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> Reviewed-by: Archit Taneja <archit@ti.com>
> ---
> .../devicetree/bindings/video/ti,tpd12s015.txt | 44 ++++++++++++++++++++++
> 1 file changed, 44 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/video/ti,tpd12s015.txt
>
> diff --git a/Documentation/devicetree/bindings/video/ti,tpd12s015.txt b/Documentation/devicetree/bindings/video/ti,tpd12s015.txt
> new file mode 100644
> index 000000000000..26e6d32e3f20
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/video/ti,tpd12s015.txt
> @@ -0,0 +1,44 @@
> +TPD12S015 HDMI level shifter and ESD protection chip
> +==========================
> +
> +Required properties:
> +- compatible: "ti,tpd12s015"
> +
> +Optional properties:
> +- gpios: CT CP HPD, LS OE and HPD gpios
If this is supposed to give people a clue about what these GPIOs are,
it completely fails to do this. CT CP? HPD is obviously the hotplug
detect signal, but why are there two - HDMI only has a single detect
pin on the connector.
While it makes sense to stick all three into one property, is it
possible that not all of these may be routed to a GPIO? If so, how
do you specify that one (or more) of these does not exist?
Another issue here is that other HDMI encoders are available - should
every encoder define its own set of bindings, or should there be a
base set of bindings which all encoders should conform to - such as
always having a HDMI output port?
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
^ permalink raw reply
* Re: [PATCH 4/9] Doc/DT: Add DT binding documentation for HDMI Connector
From: Tomi Valkeinen @ 2014-02-28 16:15 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: devicetree, linux-fbdev, Sascha Hauer, Tomasz Figa, dri-devel,
Inki Dae, Andrzej Hajda, Rob Clark, Thierry Reding,
Laurent Pinchart, Philipp Zabel, linux-arm-kernel,
Sebastian Hesselbarth
In-Reply-To: <20140228160612.GR21483@n2100.arm.linux.org.uk>
[-- Attachment #1: Type: text/plain, Size: 1093 bytes --]
On 28/02/14 18:06, Russell King - ARM Linux wrote:
>> +hdmi0: connector@1 {
>> + compatible = "hdmi-connector";
>> + label = "hdmi";
>> +
>> + hdmi_connector_in: endpoint {
>> + remote-endpoint = <&tpd12s015_out>;
>> + };
>> +};
>
> It seems rather weird to have DVI connectors having an optional I2C
> property, but HDMI (which augments DVI) not having that as at least an
> optional property.
I have added only the properties that I have used. I did think about the
i2c for HDMI also, but thought that I don't use it, and so can't test
it, and so I could well create a bad binding.
And, as I don't see any issue in adding it later, when someone uses it,
I decided to leave it out.
> I can quite well see the iMX HDMI support needing an i2c bus here.
>
> Also, HDMI has two connector standards - type A and type B, much like
> the single vs dual link of DVI. Again, DRM exposes this to userspace.
True, but isn't that just a form factor? No functional differences? But
I agree, we can add the two types here also to the compatible string.
Tomi
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 901 bytes --]
^ permalink raw reply
* Re: [PATCH 3/9] Doc/DT: Add DT binding documentation for DVI Connector
From: Russell King - ARM Linux @ 2014-02-28 16:23 UTC (permalink / raw)
To: Tomi Valkeinen
Cc: linux-fbdev-u79uwXL29TY76Z2rM5mHXA,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r, Philipp Zabel,
Laurent Pinchart, Sascha Hauer, Sebastian Hesselbarth, Rob Clark,
Inki Dae, Andrzej Hajda, Tomasz Figa, Thierry Reding
In-Reply-To: <5310B567.7040605-l0cyMroinI0@public.gmane.org>
On Fri, Feb 28, 2014 at 06:12:23PM +0200, Tomi Valkeinen wrote:
> On 28/02/14 17:59, Russell King - ARM Linux wrote:
>
> >> +dvi0: connector@0 {
> >> + compatible = "dvi-connector";
> >> + label = "dvi";
> >> +
> >> + i2c-bus = <&i2c3>;
> >> +
> >> + dvi_connector_in: endpoint {
> >> + remote-endpoint = <&tfp410_out>;
> >> + };
> >> +};
> >
> > This looks far too simplistic. There are different classes of DVI
> > connector - there is:
> >
> > DVI A - analogue only
> > DVI D - digital only (single and dual link)
> > DVI I - both (single and dual digital link)
> >
> > DRM at least makes a distinction between these three classes, and this
> > disctinction is part of the user API. How would a display system know
> > which kind of DVI connector is wired up on the board from this DT
> > description?
>
> Yes, I think that's a valid change. But do we also need to specify
> single/dual link, in addition to the three types?
I would argue that as it's a difference in physical hardware, then it
should be described in DT, even if we don't use it. The reasoning is
that although we may not use it today, we may need to use it in the
future, and as we're describing what the hardware actually is - and
even in this case what pins may be present or missing on the connector,
it's unlikely to be problematical (the only problem is when someone
omits it...)
> I guess the compatible string is the easiest way for differentation, at
> least for the three main types, i.e. "dvi-d-connector" etc.
>
> "dvi-d-1l-connector" and "dvi-d-2l-connector" for the single/dual link?
> That looks a bit funny.
I think that starts getting a tad messy:
dvi-a-connector
dvi-d-1l-connector
dvi-d-2l-connector
dvi-i-1l-connector
dvi-i-2l-connector
That's rather a lot of compatible strings. Another possibility is:
compatible = "dvi-connector";
analog;
digital;
single-link;
dual-link;
I'm debating whether "-signalling" should be on the 2nd and 3rd (or...
-signaling depending on how you prefer to spell that word.) At least
one of "analog" and/or "digital" must be specified, and if "digital"
is specified, then exactly one of "single-link" or "dual-link" should
be specified.
So, this would mean we end up with:
compatible = "dvi-connector";
analog;
digital;
dual-link;
for a DVI-I dual-link connector.
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
^ permalink raw reply
* Re: [PATCH 3/9] Doc/DT: Add DT binding documentation for DVI Connector
From: Sebastian Reichel @ 2014-02-28 16:25 UTC (permalink / raw)
To: Tomi Valkeinen
Cc: Russell King - ARM Linux, devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-fbdev-u79uwXL29TY76Z2rM5mHXA, Sascha Hauer, Tomasz Figa,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW, Inki Dae,
Andrzej Hajda, Rob Clark, Thierry Reding, Laurent Pinchart,
Philipp Zabel, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
Sebastian Hesselbarth
In-Reply-To: <5310B567.7040605-l0cyMroinI0@public.gmane.org>
[-- Attachment #1: Type: text/plain, Size: 1480 bytes --]
On Fri, Feb 28, 2014 at 06:12:23PM +0200, Tomi Valkeinen wrote:
> On 28/02/14 17:59, Russell King - ARM Linux wrote:
>
> >> +dvi0: connector@0 {
> >> + compatible = "dvi-connector";
> >> + label = "dvi";
> >> +
> >> + i2c-bus = <&i2c3>;
> >> +
> >> + dvi_connector_in: endpoint {
> >> + remote-endpoint = <&tfp410_out>;
> >> + };
> >> +};
> >
> > This looks far too simplistic. There are different classes of DVI
> > connector - there is:
> >
> > DVI A - analogue only
> > DVI D - digital only (single and dual link)
> > DVI I - both (single and dual digital link)
> >
> > DRM at least makes a distinction between these three classes, and this
> > disctinction is part of the user API. How would a display system know
> > which kind of DVI connector is wired up on the board from this DT
> > description?
>
> Yes, I think that's a valid change. But do we also need to specify
> single/dual link, in addition to the three types?
>
> I guess the compatible string is the easiest way for differentation, at
> least for the three main types, i.e. "dvi-d-connector" etc.
>
> "dvi-d-1l-connector" and "dvi-d-2l-connector" for the single/dual link?
> That looks a bit funny.
maybe like this:
Required Properties:
- compatible: should contain one of the following:
* "dvi-d-connector"
* "dvi-a-connector"
* "dvi-i-connector"
Optional Properties:
- dual-link: Should be set for dual-link capable connectors
-- Sebastian
[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]
^ permalink raw reply
* Re: [PATCH 3/9] Doc/DT: Add DT binding documentation for DVI Connector
From: Philipp Zabel @ 2014-02-28 16:25 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: Tomi Valkeinen, linux-fbdev-u79uwXL29TY76Z2rM5mHXA,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r,
Laurent Pinchart, Sascha Hauer, Sebastian Hesselbarth, Rob Clark,
Inki Dae, Andrzej Hajda, Tomasz Figa, Thierry Reding
In-Reply-To: <20140228155937.GQ21483-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
Am Freitag, den 28.02.2014, 15:59 +0000 schrieb Russell King - ARM
Linux:
> On Fri, Feb 28, 2014 at 02:20:10PM +0200, Tomi Valkeinen wrote:
> > Add DT binding documentation for DVI Connector.
> >
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
> > Reviewed-by: Archit Taneja <archit@ti.com>
> > ---
> > .../devicetree/bindings/video/dvi-connector.txt | 26 ++++++++++++++++++++++
> > 1 file changed, 26 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/video/dvi-connector.txt
> >
> > diff --git a/Documentation/devicetree/bindings/video/dvi-connector.txt b/Documentation/devicetree/bindings/video/dvi-connector.txt
> > new file mode 100644
> > index 000000000000..6a0aff866c78
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/video/dvi-connector.txt
> > @@ -0,0 +1,26 @@
> > +DVI Connector
> > +=======
> > +
> > +Required properties:
> > +- compatible: "dvi-connector"
> > +
> > +Optional properties:
> > +- label: a symbolic name for the connector
> > +- i2c-bus: phandle to the i2c bus that is connected to DVI DDC
> > +
> > +Required nodes:
> > +- Video port for DVI input
> > +
> > +Example
> > +-------
> > +
> > +dvi0: connector@0 {
> > + compatible = "dvi-connector";
> > + label = "dvi";
> > +
> > + i2c-bus = <&i2c3>;
> > +
> > + dvi_connector_in: endpoint {
> > + remote-endpoint = <&tfp410_out>;
> > + };
> > +};
>
> This looks far too simplistic. There are different classes of DVI
> connector - there is:
>
> DVI A - analogue only
> DVI D - digital only (single and dual link)
> DVI I - both (single and dual digital link)
>
> DRM at least makes a distinction between these three classes, and this
> disctinction is part of the user API. How would a display system know
> which kind of DVI connector is wired up on the board from this DT
> description?
Maybe this could be inferred from the sources connected to it. For
example a i.MX5 board with the SoC internal TV Encoder and an external
SiI902x HDMI encoder connected to the same DVI I connector:
ipu {
port@2 {
ipu_di0_disp0: endpoint {
remote-endpoint = <&sii902x_in>;
};
};
port@3 {
ipu_di1_tve: endpoint {
remote-endpoint = <&tve_in>;
};
};
};
&sii902x {
compatible = "si,sii9022";
port@0 {
sii902x_in: endpoint {
remote-endpoint = <&ipu_di0>;
};
};
port@1 {
sii902x_out: endpoint {
remote-endpoint = <&dvi_d_in>;
};
};
};
&tve {
compatible = "fsl,imx53-tve";
port@0 {
tve_in: endpoint {
remote-endpoint = <&ipu_di1>;
};
};
port@1 {
tve_out: endpoint {
remote-endpoint = <&dvi_a_in>;
};
};
};
dvi-connector {
compatible = "dvi-connector";
ddc-i2c-bus = <&i2c3>;
port {
dvi_d_in: endpoint@0 {
remote-endpoint = <&sii902x_out>;
};
dvi_a_in: endpoint@1 {
remote-endpoint = <&tve_out>;
};
};
};
It should be possible to let the connector know that those two endpoints
are connected to a TMDS source and to a VGA source, respectively.
regards
Philipp
^ permalink raw reply
* Re: [PATCH 0/9] Doc/DT: DT bindings for various display components
From: Russell King - ARM Linux @ 2014-02-28 16:27 UTC (permalink / raw)
To: Tomi Valkeinen
Cc: linux-fbdev-u79uwXL29TY76Z2rM5mHXA,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r, Philipp Zabel,
Laurent Pinchart, Sascha Hauer, Sebastian Hesselbarth, Rob Clark,
Inki Dae, Andrzej Hajda, Tomasz Figa, Thierry Reding
In-Reply-To: <1393590016-9361-1-git-send-email-tomi.valkeinen-l0cyMroinI0@public.gmane.org>
On Fri, Feb 28, 2014 at 02:20:07PM +0200, Tomi Valkeinen wrote:
> Shortly about the display components in the series, in the order of probable
> public interest:
>
> * Analog TV, DVI and HDMI Connectors represent a respective connector on the
> board. They don't do much, but they do mark the end of the video pipeline (from
> the board's pov), and they should also in the future offer ways to handle
> things like the +5V pin on DVI and HDMI connector and HPD pin.
The big thing which concerns me is that we're using very generic
compatible strings here - has anyone done any searches to see whether
there are any existing standards for this kind of stuff already?
Even if none can be found, if we're going to create something like
this, it should probably become a public standard not just for Linux.
If we're not willing to do that, I'd suggest prefixing the compatible
strings with "linux," as a "company" identifier so that there's no
chance that we may hit some major problem caused by a conflicting
implementation in the future.
We could alternatively take the view that Linux will only ever be used
with Linux specific DT files, but I think that's a rather broken
approach given what DT is supposed to be.
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
^ permalink raw reply
* Re: [PATCH 3/9] Doc/DT: Add DT binding documentation for DVI Connector
From: Warner Losh @ 2014-02-28 16:28 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: Tomi Valkeinen, linux-fbdev-u79uwXL29TY76Z2rM5mHXA,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r, Philipp Zabel,
Laurent Pinchart, Sascha Hauer, Sebastian Hesselbarth, Rob Clark,
Inki Dae, Andrzej Hajda, Tomasz Figa, Thierry Reding
In-Reply-To: <20140228162327.GT21483-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
On Feb 28, 2014, at 9:23 AM, Russell King - ARM Linux <linux@arm.linux.org.uk> wrote:
> On Fri, Feb 28, 2014 at 06:12:23PM +0200, Tomi Valkeinen wrote:
>> On 28/02/14 17:59, Russell King - ARM Linux wrote:
>>
>>>> +dvi0: connector@0 {
>>>> + compatible = "dvi-connector";
>>>> + label = "dvi";
>>>> +
>>>> + i2c-bus = <&i2c3>;
>>>> +
>>>> + dvi_connector_in: endpoint {
>>>> + remote-endpoint = <&tfp410_out>;
>>>> + };
>>>> +};
>>>
>>> This looks far too simplistic. There are different classes of DVI
>>> connector - there is:
>>>
>>> DVI A - analogue only
>>> DVI D - digital only (single and dual link)
>>> DVI I - both (single and dual digital link)
>>>
>>> DRM at least makes a distinction between these three classes, and this
>>> disctinction is part of the user API. How would a display system know
>>> which kind of DVI connector is wired up on the board from this DT
>>> description?
>>
>> Yes, I think that's a valid change. But do we also need to specify
>> single/dual link, in addition to the three types?
>
> I would argue that as it's a difference in physical hardware, then it
> should be described in DT, even if we don't use it. The reasoning is
> that although we may not use it today, we may need to use it in the
> future, and as we're describing what the hardware actually is - and
> even in this case what pins may be present or missing on the connector,
> it's unlikely to be problematical (the only problem is when someone
> omits it...)
And the “we” that uses the DT files is larger than just the Linux, and one of
those systems may use it.
Warner
^ permalink raw reply
* Re: [PATCH 9/9] Doc/DT: Add DT binding documentation for tpd12s015 encoder
From: Tomi Valkeinen @ 2014-02-28 16:30 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: devicetree, linux-fbdev, Sascha Hauer, Tomasz Figa, dri-devel,
Inki Dae, Andrzej Hajda, Rob Clark, Thierry Reding,
Laurent Pinchart, Philipp Zabel, linux-arm-kernel,
Sebastian Hesselbarth
In-Reply-To: <20140228161343.GS21483@n2100.arm.linux.org.uk>
[-- Attachment #1: Type: text/plain, Size: 3329 bytes --]
On 28/02/14 18:13, Russell King - ARM Linux wrote:
> On Fri, Feb 28, 2014 at 02:20:16PM +0200, Tomi Valkeinen wrote:
>> Add DT binding documentation for tpd12s015 encoder
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
>> Reviewed-by: Archit Taneja <archit@ti.com>
>> ---
>> .../devicetree/bindings/video/ti,tpd12s015.txt | 44 ++++++++++++++++++++++
>> 1 file changed, 44 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/video/ti,tpd12s015.txt
>>
>> diff --git a/Documentation/devicetree/bindings/video/ti,tpd12s015.txt b/Documentation/devicetree/bindings/video/ti,tpd12s015.txt
>> new file mode 100644
>> index 000000000000..26e6d32e3f20
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/video/ti,tpd12s015.txt
>> @@ -0,0 +1,44 @@
>> +TPD12S015 HDMI level shifter and ESD protection chip
>> +====================================================
>> +
>> +Required properties:
>> +- compatible: "ti,tpd12s015"
>> +
>> +Optional properties:
>> +- gpios: CT CP HPD, LS OE and HPD gpios
>
> If this is supposed to give people a clue about what these GPIOs are,
> it completely fails to do this. CT CP? HPD is obviously the hotplug
> detect signal, but why are there two - HDMI only has a single detect
> pin on the connector.
No, it's not supposed to give a clue. But if you have a TPD chip on your
board, and you use it and write a dts file, you need to know what those
GPIOs are and where they are connected. They're described in the TPD
spec and should be visible on your boards schematics.
I did stop a few times when writing the binding docs, trying to decide
when I should go to details and when not. I usually decided that if the
particular information is 100% if you have the component spec sheet, I'm
not describing it here.
I don't even know what "CT CP" is short for, and I don't remember the
spec telling it... It does tell how to use it, though.
> While it makes sense to stick all three into one property, is it
> possible that not all of these may be routed to a GPIO? If so, how
> do you specify that one (or more) of these does not exist?
The normal way, leave it out. From
Documentation/devicetree/bindings/gpio/gpio.txt:
chipsel-gpios = <&gpio1 12 0>,
<&gpio1 13 0>,
<0>, /* holes are permitted, means no GPIO 2 */
<&gpio2 2>;
> Another issue here is that other HDMI encoders are available - should
> every encoder define its own set of bindings, or should there be a
> base set of bindings which all encoders should conform to - such as
> always having a HDMI output port?
The TPD is not an actual HDMI encoder, it's a level shifter, ESD
protection companion chip for the actual HDMI encoder.
But as for your question... I don't know. I don't know how much common
things there are. An HDMI encoder could have, say, two output ports. And
the encoder could have various number of input ports, so you can't say
either that the second port is always an output port.
If I had to make a guess right now, I'd guess that there are not enough
common things to justify defining common parts for all HDMI encoders.
But I have only dealt with the OMAP HDMI encoders, and a few one's from
Toshiba (DPI to HDMI and DSI to HDMI).
Tomi
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 901 bytes --]
^ permalink raw reply
* Re: [PATCH 4/9] Doc/DT: Add DT binding documentation for HDMI Connector
From: Russell King - ARM Linux @ 2014-02-28 16:34 UTC (permalink / raw)
To: Tomi Valkeinen
Cc: devicetree, linux-fbdev, dri-devel, Andrzej Hajda,
Laurent Pinchart, linux-arm-kernel, Sebastian Hesselbarth
In-Reply-To: <5310B609.1010105@ti.com>
On Fri, Feb 28, 2014 at 06:15:05PM +0200, Tomi Valkeinen wrote:
> On 28/02/14 18:06, Russell King - ARM Linux wrote:
>
> >> +hdmi0: connector@1 {
> >> + compatible = "hdmi-connector";
> >> + label = "hdmi";
> >> +
> >> + hdmi_connector_in: endpoint {
> >> + remote-endpoint = <&tpd12s015_out>;
> >> + };
> >> +};
> >
> > It seems rather weird to have DVI connectors having an optional I2C
> > property, but HDMI (which augments DVI) not having that as at least an
> > optional property.
>
> I have added only the properties that I have used. I did think about the
> i2c for HDMI also, but thought that I don't use it, and so can't test
> it, and so I could well create a bad binding.
>
> And, as I don't see any issue in adding it later, when someone uses it,
> I decided to leave it out.
>
> > I can quite well see the iMX HDMI support needing an i2c bus here.
> >
> > Also, HDMI has two connector standards - type A and type B, much like
> > the single vs dual link of DVI. Again, DRM exposes this to userspace.
>
> True, but isn't that just a form factor? No functional differences? But
> I agree, we can add the two types here also to the compatible string.
HDMI A is 19 pins carrying TMDS channels 0-2. HDMI B is 29 pins
carrying TMDS channels 0-5. So, the difference is the same as the
single vs dual link on DVI-D/I connectors.
There's actually three HDMI connectors:
All three connectors carry all required HDMI signals, including a TMDS
link. The Type B connector is slightly larger and carries a second TMDS
link, which is necessary to support very high resolution displays using
dual link. The Type C connector carries the same signals as the Type A
but is more compact and intended for mobile applications.
So, Type C and Type A are electrically the same.
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
^ permalink raw reply
* Re: [PATCH 0/9] Doc/DT: DT bindings for various display components
From: Russell King - ARM Linux @ 2014-02-28 16:48 UTC (permalink / raw)
To: Sebastian Hesselbarth
Cc: devicetree, linux-fbdev, dri-devel, Andrzej Hajda, Tomi Valkeinen,
Laurent Pinchart, linux-arm-kernel
In-Reply-To: <5310945A.9040106@gmail.com>
On Fri, Feb 28, 2014 at 02:51:22PM +0100, Sebastian Hesselbarth wrote:
> Is it really the logical place to handle HPD? I'd have put it into the
> HDMI encoder because it's the unit most interested in the state of HPD.
I think this is where differences in hardware become a problem.
Yes, it makes sense to handle the HPD at the encoder level, because
your HDMI encoder may require a HPD signal from the connector, and it
may handle this internally.
However, it's also true that the HPD signal from the HDMI connector may
be routed directly to a GPIO on the SoC.
Both are equally valid - and actually something which DRM as a subsystem
understands:
struct drm_connector_funcs {
enum drm_connector_status (*detect)(struct drm_connector *connector,
bool force);
};
struct drm_encoder_helper_funcs {
enum drm_connector_status (*detect)(struct drm_encoder *encoder,
struct drm_connector *connector);
};
although the original intention for the encoder detection method was for
DAC-style detection, such as found on Intel adapters (which regularly
pulse the R,G,B signals and measure any attached load.) We also use
the encoder detection method for TDA998x on Dove (currently via the
slave encoder stuff.)
So, I'd say that there's scope for a HDMI connector having a hotplug
GPIO attached to it - and if it isn't there (and there's no other form
of connector-based detection), the connector should refer to it's
attached encoder for connect status.
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
^ permalink raw reply
* Re: [PATCH 0/9] Doc/DT: DT bindings for various display components
From: Tomi Valkeinen @ 2014-02-28 16:48 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: linux-fbdev-u79uwXL29TY76Z2rM5mHXA,
dri-devel-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW,
devicetree-u79uwXL29TY76Z2rM5mHXA,
linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r, Philipp Zabel,
Laurent Pinchart, Sascha Hauer, Sebastian Hesselbarth, Rob Clark,
Inki Dae, Andrzej Hajda, Tomasz Figa, Thierry Reding
In-Reply-To: <20140228162752.GU21483-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
[-- Attachment #1: Type: text/plain, Size: 1929 bytes --]
On 28/02/14 18:27, Russell King - ARM Linux wrote:
> On Fri, Feb 28, 2014 at 02:20:07PM +0200, Tomi Valkeinen wrote:
>> Shortly about the display components in the series, in the order of probable
>> public interest:
>>
>> * Analog TV, DVI and HDMI Connectors represent a respective connector on the
>> board. They don't do much, but they do mark the end of the video pipeline (from
>> the board's pov), and they should also in the future offer ways to handle
>> things like the +5V pin on DVI and HDMI connector and HPD pin.
>
> The big thing which concerns me is that we're using very generic
> compatible strings here - has anyone done any searches to see whether
> there are any existing standards for this kind of stuff already?
I did look for any display related DT bindings when I started the work
on OMAP DSS DT bindings. I didn't really find any. If I recall right,
the only thing I found was an example of basically:
fb@1234567 {
compatible="asd";
reg=<1234567>;
};
So just a node for "framebuffer", with the register addresses. And maybe
video timings in some form.
Maybe I didn't know where to look.
> Even if none can be found, if we're going to create something like
> this, it should probably become a public standard not just for Linux.
This is totally unclear to me. How does it become a public standard?
What's the forum for this?
> If we're not willing to do that, I'd suggest prefixing the compatible
> strings with "linux," as a "company" identifier so that there's no
> chance that we may hit some major problem caused by a conflicting
> implementation in the future.
I don't have an issue with "linux," either. We could always later remove
the prefix (but keep drivers compatible with it). So it sounds quite a
safe approach to me, if we're not quite clear if these bindings are
acceptable, or how to get "public approval" for them.
Tomi
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 901 bytes --]
^ permalink raw reply
* Re: [PATCH 0/9] Doc/DT: DT bindings for various display components
From: Russell King - ARM Linux @ 2014-02-28 16:56 UTC (permalink / raw)
To: Tomi Valkeinen
Cc: devicetree, linux-fbdev, dri-devel, Andrzej Hajda,
Laurent Pinchart, linux-arm-kernel, Sebastian Hesselbarth
In-Reply-To: <5310BDE3.60603@ti.com>
On Fri, Feb 28, 2014 at 06:48:35PM +0200, Tomi Valkeinen wrote:
> This is totally unclear to me. How does it become a public standard?
> What's the forum for this?
Me too. That's where I'd hope someone on devicetree-discuss will be
able to help us work out what's the right approach here. :)
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
^ permalink raw reply
* Re: [PATCH 2/3] imx-drm: ipu-dc: Use usleep_range instead of msleep
From: Russell King - ARM Linux @ 2014-02-28 19:31 UTC (permalink / raw)
To: linux-fbdev
In-Reply-To: <1393328624-28013-3-git-send-email-p.zabel@pengutronix.de>
On Tue, Feb 25, 2014 at 12:43:42PM +0100, Philipp Zabel wrote:
> Since msleep(2) can sleep up to 20ms anyway, make this explicit by using
> usleep_range(2000, 20000).
>
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> ---
> drivers/staging/imx-drm/ipu-v3/ipu-dc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/staging/imx-drm/ipu-v3/ipu-dc.c b/drivers/staging/imx-drm/ipu-v3/ipu-dc.c
> index d0e3bc3..d5de8bb 100644
> --- a/drivers/staging/imx-drm/ipu-v3/ipu-dc.c
> +++ b/drivers/staging/imx-drm/ipu-v3/ipu-dc.c
> @@ -262,7 +262,7 @@ void ipu_dc_disable_channel(struct ipu_dc *dc)
>
> /* Wait for DC triple buffer to empty */
> while ((readl(priv->dc_reg + DC_STAT) & val) != val) {
> - msleep(2);
> + usleep_range(2000, 20000);
> timeout -= 2;
> if (timeout <= 0)
> break;
Umm, something which Greg may have missed.
timeout is 50. It gets decremented by two each time around this loop,
so we could end up waiting between 100ms and 1s here, yes? The exact
delay here would depend on the kernel HZ value (which is configurable,
up to 1kHz.)
So... we're using a sleeping function here (msleep or usleep_range),
and so interrupts can't be disabled here, nor can spinlocks be held,
so I'm left wondering why the code doesn't do:
timeout = jiffies + msecs_to_jiffies(100);
do {
if (readl(priv->dc_reg + DC_STAT) & val) = val)
break;
usleep_range(2000, 20000);
} while (time_is_after_jiffies(timeout));
here. (Note that whether we succeed or timeout appears to have no
effect on the following code.)
--
FTTC broadband for 0.8mile line: now at 9.7Mbps down 460kbps up... slowly
improving, and getting towards what was expected from it.
^ permalink raw reply
* Re: [PATCH 4/9] Doc/DT: Add DT binding documentation for HDMI Connector
From: Geert Uytterhoeven @ 2014-03-01 18:58 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: devicetree@vger.kernel.org, Linux Fbdev development list,
DRI Development, Andrzej Hajda, Tomi Valkeinen, Laurent Pinchart,
linux-arm-kernel@lists.infradead.org, Sebastian Hesselbarth
In-Reply-To: <20140228163431.GV21483@n2100.arm.linux.org.uk>
On Fri, Feb 28, 2014 at 5:34 PM, Russell King - ARM Linux
<linux@arm.linux.org.uk> wrote:
> There's actually three HDMI connectors:
>
> All three connectors carry all required HDMI signals, including a TMDS
> link. The Type B connector is slightly larger and carries a second TMDS
> link, which is necessary to support very high resolution displays using
> dual link. The Type C connector carries the same signals as the Type A
> but is more compact and intended for mobile applications.
>
> So, Type C and Type A are electrically the same.
There's also D (e.g. on BeagleBone Black) and E:
http://en.wikipedia.org/wiki/HDMI#Connectors
Electrically they seem to be the same as A/C.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply
* Re: [PATCH 5/9] Doc/DT: Add DT binding documentation for MIPI DPI Panel
From: Tomi Valkeinen @ 2014-03-03 6:05 UTC (permalink / raw)
To: Philipp Zabel
Cc: devicetree, linux-fbdev, Russell King - ARM Linux, Sascha Hauer,
Tomasz Figa, dri-devel, Inki Dae, Andrzej Hajda, Rob Clark,
Thierry Reding, Laurent Pinchart, linux-arm-kernel,
Sebastian Hesselbarth
In-Reply-To: <1393594836.3802.32.camel@paszta.hi.pengutronix.de>
[-- Attachment #1: Type: text/plain, Size: 1438 bytes --]
On 28/02/14 15:40, Philipp Zabel wrote:
> Am Freitag, den 28.02.2014, 14:20 +0200 schrieb Tomi Valkeinen:
>> Add DT binding documentation for MIPI DPI Panel.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
>> Reviewed-by: Archit Taneja <archit@ti.com>
>> ---
>> .../devicetree/bindings/video/panel-dpi.txt | 43 ++++++++++++++++++++++
>> 1 file changed, 43 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/video/panel-dpi.txt
>>
>> diff --git a/Documentation/devicetree/bindings/video/panel-dpi.txt b/Documentation/devicetree/bindings/video/panel-dpi.txt
>> new file mode 100644
>> index 000000000000..72636c6f1c67
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/video/panel-dpi.txt
>> @@ -0,0 +1,43 @@
>> +Generic MIPI DPI Panel
>> +======================
>> +
>> +Required properties:
>> +- compatible: "panel-dpi"
>> +
>> +Optional properties:
>> +- label: a symbolic name for the panel
>> +- gpios: panel enable gpio and backlight enable gpio
>> +
>> +Required nodes:
>> +- "panel-timing" containing video timings
>> + (Documentation/devicetree/bindings/video/display-timing.txt)
>> +- Video port for DPI input
>
> I don't see anything MIPI specific here. Couldn't this be added to the
> existing simple-panel binding?
Hmm, well, the simple-panel bindings doesn't define video ports, and not
even a common compatible property.
Tomi
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 901 bytes --]
^ permalink raw reply
* Re: [PATCH 3/9] Doc/DT: Add DT binding documentation for DVI Connector
From: Tomi Valkeinen @ 2014-03-03 6:25 UTC (permalink / raw)
To: Philipp Zabel
Cc: devicetree, linux-fbdev, Russell King - ARM Linux, Sascha Hauer,
Tomasz Figa, dri-devel, Inki Dae, Andrzej Hajda, Rob Clark,
Thierry Reding, Laurent Pinchart, linux-arm-kernel,
Sebastian Hesselbarth
In-Reply-To: <1393595008.3802.35.camel@paszta.hi.pengutronix.de>
[-- Attachment #1: Type: text/plain, Size: 1294 bytes --]
On 28/02/14 15:43, Philipp Zabel wrote:
> Hi Tomi,
>
> Am Freitag, den 28.02.2014, 14:20 +0200 schrieb Tomi Valkeinen:
>> Add DT binding documentation for DVI Connector.
>>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
>> Reviewed-by: Archit Taneja <archit@ti.com>
>> ---
>> .../devicetree/bindings/video/dvi-connector.txt | 26 ++++++++++++++++++++++
>> 1 file changed, 26 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/video/dvi-connector.txt
>>
>> diff --git a/Documentation/devicetree/bindings/video/dvi-connector.txt b/Documentation/devicetree/bindings/video/dvi-connector.txt
>> new file mode 100644
>> index 000000000000..6a0aff866c78
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/video/dvi-connector.txt
>> @@ -0,0 +1,26 @@
>> +DVI Connector
>> +==============
>> +
>> +Required properties:
>> +- compatible: "dvi-connector"
>> +
>> +Optional properties:
>> +- label: a symbolic name for the connector
>> +- i2c-bus: phandle to the i2c bus that is connected to DVI DDC
>
> For the i.MX bindings I had called this property 'ddc', but
> Documentation/devicetree/bindings/panel/simple-panel.txt already
> uses 'ddc-i2c-bus'. We should definitely standardize this.
I like 'ddc-i2c-bus'.
Tomi
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 901 bytes --]
^ permalink raw reply
* Re: [PATCH 3/9] Doc/DT: Add DT binding documentation for DVI Connector
From: Tomi Valkeinen @ 2014-03-03 6:42 UTC (permalink / raw)
To: Russell King - ARM Linux
Cc: devicetree, linux-fbdev, Sascha Hauer, Tomasz Figa, dri-devel,
Inki Dae, Andrzej Hajda, Rob Clark, Thierry Reding,
Laurent Pinchart, Philipp Zabel, linux-arm-kernel,
Sebastian Hesselbarth
In-Reply-To: <20140228162327.GT21483@n2100.arm.linux.org.uk>
[-- Attachment #1: Type: text/plain, Size: 1613 bytes --]
On 28/02/14 18:23, Russell King - ARM Linux wrote:
>> I guess the compatible string is the easiest way for differentation, at
>> least for the three main types, i.e. "dvi-d-connector" etc.
>>
>> "dvi-d-1l-connector" and "dvi-d-2l-connector" for the single/dual link?
>> That looks a bit funny.
>
> I think that starts getting a tad messy:
>
> dvi-a-connector
> dvi-d-1l-connector
> dvi-d-2l-connector
> dvi-i-1l-connector
> dvi-i-2l-connector
Yes, it's messy. Pondering this over the weekend, I think it makes sense
to have just one compatible string, as all those connectors are still
the same DVI connector, just different variations of the same.
> That's rather a lot of compatible strings. Another possibility is:
>
> compatible = "dvi-connector";
> analog;
> digital;
> single-link;
> dual-link;
>
> I'm debating whether "-signalling" should be on the 2nd and 3rd (or...
> -signaling depending on how you prefer to spell that word.) At least
> one of "analog" and/or "digital" must be specified, and if "digital"
> is specified, then exactly one of "single-link" or "dual-link" should
> be specified.
>
> So, this would mean we end up with:
>
> compatible = "dvi-connector";
> analog;
> digital;
> dual-link;
>
> for a DVI-I dual-link connector.
Another option would be:
num-links = 2;
But I like your suggestion more. We could also optimize it, "digital" is
extra as both "single-link" and "dual-link" mean also digital. But... I
don't see much point in optimizing that way. So I agree with your
suggestion as is.
Tomi
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 901 bytes --]
^ permalink raw reply
* Re: [PATCH 4/9] Doc/DT: Add DT binding documentation for HDMI Connector
From: Tomi Valkeinen @ 2014-03-03 7:23 UTC (permalink / raw)
To: Geert Uytterhoeven, Russell King - ARM Linux
Cc: devicetree@vger.kernel.org, Linux Fbdev development list,
Sascha Hauer, Tomasz Figa, DRI Development, Inki Dae,
Andrzej Hajda, Rob Clark, Thierry Reding, Laurent Pinchart,
Philipp Zabel, linux-arm-kernel@lists.infradead.org,
Sebastian Hesselbarth
In-Reply-To: <CAMuHMdVpT2Y-KQO46o=zbRSgqgx2mbBsPjGgoTDDwwfCOxUCmw@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1181 bytes --]
On 01/03/14 20:58, Geert Uytterhoeven wrote:
> On Fri, Feb 28, 2014 at 5:34 PM, Russell King - ARM Linux
> <linux@arm.linux.org.uk> wrote:
>> There's actually three HDMI connectors:
>>
>> All three connectors carry all required HDMI signals, including a TMDS
>> link. The Type B connector is slightly larger and carries a second TMDS
>> link, which is necessary to support very high resolution displays using
>> dual link. The Type C connector carries the same signals as the Type A
>> but is more compact and intended for mobile applications.
>>
>> So, Type C and Type A are electrically the same.
>
> There's also D (e.g. on BeagleBone Black) and E:
>
> http://en.wikipedia.org/wiki/HDMI#Connectors
>
> Electrically they seem to be the same as A/C.
Right. And then there are the HDMI versions, and things like HDMI
Ethernet Channel. After looking at these a bit, I don't think the HDMI
connector needs any of those (hdmi version, eth) defined.
So...
compatible = "hdmi-connector";
type = "a";
Or
compatible = "hdmi-connector";
type-a;
I don't right away see any big pro with either one compared to the other.
Tomi
[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 901 bytes --]
^ permalink raw reply
page: next (older) | prev (newer) | latest
- recent:[subjects (threaded)|topics (new)|topics (active)]
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox