Hi Nikolaus,
Le mer., mars 11, 2020 at 13:43, H. Nikolaus Schaller
<hns@xxxxxxxxxxxxx> a écrit :
Hi Paul,
Am 02.03.2020 um 20:27 schrieb Paul Cercueil <paul@xxxxxxxxxxxxxxx>:
Hi Nikolaus,
Le ven., févr. 28, 2020 at 19:19, H. Nikolaus Schaller
<hns@xxxxxxxxxxxxx> a écrit :
From: Paul Boddie <paul@xxxxxxxxxxxxx>
A specialisation of the generic Synopsys HDMI driver is employed
for JZ4780
HDMI support. This requires a new driver, plus device tree and
configuration
modifications.
Signed-off-by: Paul Boddie <paul@xxxxxxxxxxxxx>
Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>
---
arch/mips/boot/dts/ingenic/jz4780.dtsi | 32
++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/arch/mips/boot/dts/ingenic/jz4780.dtsi
b/arch/mips/boot/dts/ingenic/jz4780.dtsi
index f928329b034b..391d4e1efd35 100644
--- a/arch/mips/boot/dts/ingenic/jz4780.dtsi
+++ b/arch/mips/boot/dts/ingenic/jz4780.dtsi
@@ -433,4 +433,36 @@
status = "disabled";
};
+
+ hdmi: hdmi@10180000 {
+ compatible = "ingenic,jz4780-dw-hdmi";
+ reg = <0x10180000 0x8000>;
+ reg-io-width = <4>;
+
+ clocks = <&cgu JZ4780_CLK_HDMI>, <&cgu JZ4780_CLK_AHB0>;
+ clock-names = "isfr" , "iahb";
+
+ assigned-clocks = <&cgu JZ4780_CLK_HDMI>;
+ assigned-clock-rates = <27000000>;
I *think* this should go to the board file.
+
+ interrupt-parent = <&intc>;
+ interrupts = <3>;
+
+ /* ddc-i2c-bus = <&i2c4>; */
+
+ status = "disabled";
+ };
+
+ lcd: lcd@13050000 {
The node name should be 'lcd-controller'.
+ compatible = "ingenic,jz4740-lcd";
The JZ4780's LCD controller is much newer than the JZ4740 one, so
even if it works with the "ingenic,jz4740-lcd" compatible string,
you want it as a fallback.
So this should be: compatible = "ingenic,jz4780-lcd",
"ingenic,jz4740-lcd".
That means the YAML should be updated too.
I have started to look into jz4780 HDMI setup again.
Well, there is no driver compatible to "ingenic,jz4780-lcd" so far
and it is questionalbe if we need a different one.
I think we should rather make the driver also compatible
than adding a fallback to ingenic,jz4740-lcdto the DTS.
The reason why this is better even if both LCDC are almost
compatible is that the jz4780 allows for much bigger displays
and therefore should have its own jz_soc_info with 4k x 2k
as maximum.
Sure, feel free to extend the driver.
Next I tried to find out if the LCDC are really compatible.
Well the jz4780 has two lcdc instances but they are separated
by the reg addr. Next, there are unique features (like picture in
picture with alpha blending) but those are probably disabled
if not programmed from reset state. This may become a reason
to separate or augment the driver for the jz4780 but at the
moment we can ignore that.
Two LCDC instances -> two lcd-controller@... nodes. It's that simple.
The other features you listed are outside the LCDC, so outside the
scope of this driver.
There are also subtly different bit definitions and register
widths (e.g. 24 bit in addition to 16/18 bit modes or more bits
for the sync position) but it looks as if the ingenic_drm
driver already handles this.
Then I tried to read back the registers. Strangely they
are all 0x00000000. So there is no programming of the
lcd-controller in our DT setup with HDMI at all!
How did you read them?
Do it from the regmap: should be "cat
/sys/kernel/debug/regmap/13050000.lcd-controller/registers" (not sure
about the path)
I also checked that ingenic_drm_probe() is called and
returns successfully 0. It also reports that a /dev/fb
has been created:
[ 7.908830] ingenic-drm 13050000.lcd-controller: fb0:
ingenic-drmdrmf frame buffer device
But for example ingenic_drm_encoder_atomic_mode_set() is
never called which should write some registers of the LCDC.
I only did see some calls to ingenic_drm_encoder_atomic_check().
This of course explains why we have no HDMI signals despite
proper HPD and a /dev/fb0. Because the LCDC is not being
programmed.
It won't be called until the HDMI driver says that the cable is
plugged, and there's a client application (e.g. fbdev emulation)
running. So the problem is most likely within the HDMI driver.
Cheers,
-Paul
Any ideas / hints how to check or improve?
BR and thanks,
Nikolaus
