On 03/03/2022 11:40, H. Nikolaus Schaller wrote:
Hi Neil,
Am 03.03.2022 um 09:35 schrieb Neil Armstrong <narmstrong@xxxxxxxxxxxx>:
Hi,
On 02/03/2022 23:24, H. Nikolaus Schaller wrote:
Hi Neil,
Am 02.03.2022 um 15:34 schrieb Neil Armstrong <narmstrong@xxxxxxxxxxxx>:
Hi,
(cross-checked: RGB mode still works if I force hdmi->sink_is_hdmi = false)
I don't understand what's wrong, can you try to make the logic select MEDIA_BUS_FMT_YUV8_1X24 instead of DRM_COLOR_FORMAT_YCBCR422 ?
I have forced hdmi->sink_is_hdmi = false and replaced
/* Default 8bit RGB fallback */
- output_fmts[i++] = MEDIA_BUS_FMT_RGB888_1X24;
+ output_fmts[i++] = MEDIA_BUS_FMT_YUV8_1X24;
And then screen remains black. MEDIA_BUS_FMT_RGB888_1X24 works.
(MEDIA_BUS_FMT_VUY8_1X24 doesn't work either).
So this indicates that YUV conversion is not working properly. Maybe missing some special
setup.
What I have to test if it works on a different monitor.
Same effect on a Xiaomi monitor (user manual just telling HDMI1,4 compatible), an
older Acer video projector and a Sharp TV set.
The Xiaomi monitor does not say "No signal" but shows a black screen. The others
do not even report any HDMI signals. All work well with MEDIA_BUS_FMT_RGB888_1X24.
This means the transcoding to YUV does not work properly on the jz4780 SoC setup.
So it looks as if we have to disable it (at least unless someone finds a fix).
Not that this specific panel
(a 7 inch waveshare touch with HDMIinput) is buggy and reports YUV capabilities
but does not handle them...
On the other hand this panel works on RasPi and OMAP5 (where I admit I do not know in
which mode).
Pretty sure they don't support YUV HDMI output.
If you can try on a certified HDMI devices like a TV, it would here figuring out where comes the issue.
I am not sure if the Sharp TV is fully certified but would assume...
If your CSC is broken, we'll need to disable it on your platform.
Indeed.
So it seems as if we need a mechanism to overwrite dw_hdmi_bridge_atomic_get_output_bus_fmts()
in our ingenic-dw-hdmi platform specialization [1] to always return MEDIA_BUS_FMT_RGB888_1X24.
Or alternatively set sink_is_hdmi = false there (unfortunately there is no direct access to
struct dw_hdmi in a specialization drivers).
Is this already possible or how can it be done?
It's not handled yet, but we may add the logic to handle the lack of CSC config bit and
add a glue config bit to override this like we already did for CEC.
I wrote an initial support to disable CSC (only compile-tested), could you try on your platform with setting disable_csc = 1 in your dw-hdmi glue code ?
This works!
So how can we get that merged? IMHO your proposal should be before we add ingenic-dw-hdmi.
If you have a version with proper commit message I can add it to the beginning of my
seried and include it in a v17. Or if you get yours merged to drm-misc/drm-misc-next I
can build on top.
You can add it in your v17 patchset with my authorship and my Signed-off-by tag + yours.
As commit message something like :
====================
drm/bridge: dw-hdmi: handle unusable or non-configured CSC module
The dw-hdmi integrates an optional Color Space Conversion feature used
to handle color-space conversions.
On some platforms, the CSC isn't built-in or non-functional.
This adds the necessary code to disable the CSC functionality
and limit the bus format negotiation to force using the same
input bus format as the output bus format.
====================
Thanks,
Neil
BR and thanks,
Nikolaus
