Re: [PATCH v6 3/5] ARM: dts: sun8i-h3: add HDMI video nodes

On Fri, Nov 25, 2016 at 11:22:13AM +0100, Jean-Francois Moine wrote:

On Fri, 25 Nov 2016 17:41:51 +0800
Icenowy Zheng [off-list ref] wrote:

quoted

After removing CLK_PLL_DE's assigned-clock, the kernel passes compilation.

The 'pll-de' and 'de' must have a fixed rate. Otherwise, if you do not
use the legacy u-boot, I don't know which can be the rate of the DE.

quoted

However, it cannot recognize any HDMI screen...

(My board is Orange Pi One, and I manually added status="okay"; to &lcd0, &de, &hdmi)

[   16.507802] sun8i-de2 1000000.de-controller: bound 1c0c000.lcd-controller (ops de2_lcd_ops [sun8i_de2_drm])
[   16.675948] sun8i-de2 1000000.de-controller: bound 1ee0000.hdmi (ops de2_hdmi_fini [sun8i_de2_hdmi])
[   16.685120] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[   16.695876] [drm] No driver support for vblank timestamp query.
[   16.701862] sun8i-de2 1000000.de-controller: No connectors reported connected with modes
[   16.713061] [drm] Cannot find any crtc or sizes - going 1024x768
[   16.734214] Console: switching to colour frame buffer device 128x48
[   16.751022] sun8i-de2 1000000.de-controller: fb0:  frame buffer device

I put a 'pr_warn' message is case the EDID cannot be read.
Have you this message?

Anyway, there is a problem with the EDID:
- my Orange Pi 2 (H3) randomly fails to read it. But this succeeds after
  rebooting once or twice.
- my Banana Pi M2+ (H3) reads it correctly each time.
- my Banana Pi M3 (A83T) can never read it.

BTW, on first tries, I was forcing a CEA mode thru the kernel command
line. This was working with the OPi2 and BPiM3, but there was no sound.
In the last version, I use a EDID in edid_firmware for having sound
with the BPiM3. This works fine.
But, forcing a CEA mode is no more possible, so, when the OPi2 cannot
read the EDID, the system switches to a VGA mode (default 1024x768)
which is not supported. It seems that this is your case.

So, in brief, if your board cannot read the EDID, put a EDID somewhere
and its path in /sys/module/drm_kms_helper/parameters/edid_firmware.
There will be no console, but X11 will work correctly.

This is one of the things that are usually very helpful to put in a
cover letter. This is obviously also a blocker for the merge of the
driver, and should be dealt with.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com