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

[Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>]

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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 <icenowy-ymACFijhrKM@public.gmane.org> wrote:
> 
> > 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.
> 
> > 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