Re: [PATCH v14 1/3] drm/i2c: tda998x: Add support of a DT graph of ports

On Mon, 3 Aug 2015 17:56:17 +0300
Jyri Sarha [off-list ref] wrote:

On 05/08/15 11:18, Jean-Francois Moine wrote:

quoted

Two kinds of ports may be declared in a DT graph of ports: video and audio.
This patch accepts the port value from a video port as an alternative
to the video-ports property.
It also accepts audio ports in the case the transmitter is not used as
a slave encoder.
The new file include/sound/tda998x.h prepares to the definition of
a tda998x CODEC.

Signed-off-by: Jean-Francois Moine <redacted>
---
  .../devicetree/bindings/drm/i2c/tda998x.txt        | 51 ++++++++++++
  drivers/gpu/drm/i2c/tda998x_drv.c                  | 90 +++++++++++++++++++---
  include/sound/tda998x.h                            |  8 ++
  3 files changed, 140 insertions(+), 9 deletions(-)
  create mode 100644 include/sound/tda998x.h

diff --git a/Documentation/devicetree/bindings/drm/i2c/tda998x.txt b/Documentation/devicetree/bindings/drm/i2c/tda998x.txt
index e9e4bce..35f6a80 100644
--- a/Documentation/devicetree/bindings/drm/i2c/tda998x.txt
+++ b/Documentation/devicetree/bindings/drm/i2c/tda998x.txt

@@ -16,6 +16,35 @@ Optional properties:

    - video-ports: 24 bits value which defines how the video controller
  	output is wired to the TDA998x input - default: <0x230145>
+	This property is not used when ports are defined.
+
+Optional nodes:
+
+  - port: up to three ports.
+	The ports are defined according to [1].
+
+    Video port.
+	There may be only one video port.
+	This one must contain the following property:
+
+	- port-type: must be "rgb"
+
+	and may contain the optional property:
+
+	- reg: 24 bits value which defines how the video controller
+		output is wired to the TDA998x input (video pins)
+		When absent, the default value is <0x230145>.

Using reg property for something else than for address of some kind 
seems confusing to me. Should we just add an explicit property rgb mapping?

Indeed, there could be an attribute as 'port-value'.

quoted

+
+    Audio ports.
+	There may be one or two audio ports.
+	These ones must contain the following properties:
+
+	- port-type: must be "i2s" or "spdif"
+
+	- reg: 8 bits value which defines how the audio controller
+		output is wired to the TDA998x input (audio pins)
+

Here I do not even understand what what the values 3 ad 4 stand for. 

These values come from the TDA19988 documentation (the TDA9988 and
TDA9989 have the same video and audio input registers).
- 0x03 is WS (Word Select - bit 0) = 1 (I2S) and AP (Audio Pin) = 1 (bit 1)
- 0x04 is WS = 0 (S/PDIF) and AP = 2 (bit 2)

Also when trying to make a device file following the above binding I get 
errors related the different widths of for the register property values 
(I do not have the exact error at hand right now), but that prevented me 
from using these patches when I last tried them.

Strange. I have no error.

Anyway having some clearly defined property that explicitly defines the 
audio pins would make more sense to me. Even if that is not possible due 
lack of proper documentation it would be better not add to the confusion 
by unusual usage of reg property.

I don't remember from where I got the TDA19988 documentation, but,
anyway, the port values are the same as the ones found in the first
kernel provided by the Cubox manufacturer.

Best regards,
Jyri

ps. Did you ever give my generic hdmi codec patch a try?

No, because I don't need a so complex codec. Mine has no codec device,
no private data, no clock, and it is less than 150 lines of code.
Also, as my machine is now obsolete, I will stop any development for it
and keep the kernel I have and which works fine enough for me.

Best regards.

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html