Fwd: Barebox 2017.02 works great but no Linux Framebuffer... :-/
l.stach at pengutronix.de
Tue Feb 21 07:03:00 PST 2017
Am Dienstag, den 21.02.2017, 14:04 +0100 schrieb gianluca:
> Hello everybody!
> I am fighting to enable ldb in Linux 4.9.7. In barebox the SAME
> device-tree is modified by barebox to enable/disable the ldb or hdmi
> depending on what is found.
> During Linux bootup with HDMI only, it works with no hassle.
> If booting with ldb it does not start the ldb driver registration due to
> a panel/bridge missing.
> In the config of linux kernel I have (as imx_v6_v7_defconfig) all drm
> and simple panel enabled.
> What is missing???
> Best regards,
> -------- Forwarded Message --------
> Subject: Barebox 2017.02 works great but no Linux Framebuffer... :-/
> Date: Mon, 20 Feb 2017 16:36:06 +0100
> From: gianluca <gianlucarenzi at eurekelettronica.it>
> To: Sascha Hauer <s.hauer at pengutronix.de>
> Hello Sascha,
> During last week I was able to activate/deactivate the hdmi and ldb
> nodes from internal device-tree of Barebox and everything is working great.
> Now I would like to boot up with the kernel 4.9.7 with the following
> commandline but it fails.
> The kernelcmd line is:
> > console=ttymxc2,115200 rootwait noswap ip=none noinitrd rootfstype=nilfs2 root=/dev/mmcblk1p3 fec.macaddr=0x7a,0x3f,0x03,0xe3,0xa2,0xff system_rev=0xe3600000 system_serialnr=0x00000000 lcd_type=am1280800n3tz fastboot quiet loglevel=3 console=tty0 video=mxcfb0:dev=ldb,if=RGB24,bpp=32 fbmem=32M vmalloc=400M
> The problem is the ldb (imx-ldb.c you wrote in kernel
> drivers/gpu/drm/imx...). It fails with the following error:
> > [ 7.526349] imx-ldb 2000000.aips-bus:ldb at 020e0008: panel/bridge not found: /panel --
> > [ 7.526369] imx-drm display-subsystem: failed to bind 2000000.aips-bus:ldb at 020e0008 (ops 0xc097aaa0): -517
> > [ 7.526785] imx-drm display-subsystem: master bind failed: -517
> The device-tree is attached.
> The device tree is the same as Barebox (it has only an #included
> commented out).
> Both hdmi and ldb nodes are initially left "disabled" then barebox
> enable the node corresponding to the hardware found (i.e. it changes the
> status to "okay")
> In barebox everything is working.
> In linux NOT. What is exactly a 'channel->bridge' and 'channel->panel'
> in device-tree therminology?
> Barebox is working without it, so I suppose it was working in Linux
> kernel too...
No, Linux does not support DT defined modes in the panel. You need a
panel with a proper compatible and driver.
See drivers/gpu/drm/panel. For most LVDS panels simple-panel is what you
want to use.
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