Re: [PATCH 1/2 v6] of: add helper to parse display timings
From: Guennadi Liakhovetski <hidden>
Date: 2012-10-04 21:35:35
Also in:
dri-devel, linux-devicetree, linux-media
Possibly related (same subject, not in this thread)
- 2012-10-22 · Re: [PATCH 1/2 v6] of: add helper to parse display timings · Steffen Trumtrar <hidden>
- 2012-10-20 · Re: [PATCH 1/2 v6] of: add helper to parse display timings · Thierry Reding <hidden>
- 2012-10-20 · Re: [PATCH 1/2 v6] of: add helper to parse display timings · Thierry Reding <hidden>
- 2012-10-12 · Re: [PATCH 1/2 v6] of: add helper to parse display timings · Steffen Trumtrar <hidden>
- 2012-10-11 · Re: [PATCH 1/2 v6] of: add helper to parse display timings · Thierry Reding <hidden>
Hi Steffen Sorry for chiming in so late in the game, but I've long been wanting to have a look at this and compare with what we do for V4L2, so, this seems a great opportunity to me:-) On Thu, 4 Oct 2012, Steffen Trumtrar wrote:
quoted hunk
Signed-off-by: Steffen Trumtrar <redacted> --- .../devicetree/bindings/video/display-timings.txt | 222 ++++++++++++++++++++ drivers/of/Kconfig | 5 + drivers/of/Makefile | 1 + drivers/of/of_display_timings.c | 183 ++++++++++++++++ include/linux/of_display_timings.h | 85 ++++++++ 5 files changed, 496 insertions(+) create mode 100644 Documentation/devicetree/bindings/video/display-timings.txt create mode 100644 drivers/of/of_display_timings.c create mode 100644 include/linux/of_display_timings.hdiff --git a/Documentation/devicetree/bindings/video/display-timings.txt b/Documentation/devicetree/bindings/video/display-timings.txt new file mode 100644 index 0000000..45e39bd --- /dev/null +++ b/Documentation/devicetree/bindings/video/display-timings.txt@@ -0,0 +1,222 @@ +display-timings bindings +========= + +display-timings-node +------------ + +required properties: + - none + +optional properties: + - default-timing: the default timing value + +timings-subnode +--------------- + +required properties: + - hactive, vactive: Display resolution + - hfront-porch, hback-porch, hsync-len: Horizontal Display timing parameters + in pixels + vfront-porch, vback-porch, vsync-len: Vertical display timing parameters in + lines + - clock: displayclock in Hz
You're going to hate me for this, but eventually we want to actually reference clock objects in our DT bindings. For now, even if you don't want to actually add clock phandles and stuff here, I think, using the standard "clock-frequency" property would be much better!
+ +optional properties: + - hsync-active-high (bool): Hsync pulse is active high + - vsync-active-high (bool): Vsync pulse is active high
For the above two we also considered using bool properties but eventually settled down with integer ones: - hsync-active = <1> for active-high and 0 for active low. This has the added advantage of being able to omit this property in the .dts, which then doesn't mean, that the polarity is active low, but rather, that the hsync line is not used on this hardware. So, maybe it would be good to use the same binding here too?
+ - de-active-high (bool): Data-Enable pulse is active high + - pixelclk-inverted (bool): pixelclock is inverted
We don't (yet) have a de-active property in V4L, don't know whether we'll ever have to distingsuish between what some datasheets call "HREF" and HSYNC in DT, but maybe similarly to the above an integer would be preferred. As for pixclk, we call the property "pclk-sample" and it's also an integer.
+ - interlaced (bool)
Is "interlaced" a property of the hardware, i.e. of the board? Can the same display controller on one board require interlaced data and on another board - progressive? BTW, I'm not very familiar with display interfaces, but for interlaced you probably sometimes use a field signal, whose polarity you also want to specify here? We use a "field-even-active" integer property for it. Thanks Guennadi --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/