BUG, i.MX: broken LVDS display

[Holger Schurig]

Hi,

on my i.MX6Q device barebox 2015-08.0 worked and I had an output on the splash screen, both in Barebox and later in Linux (there with CONFIG_STAGING, CONFIG_DRM_IMX, 
DRM_IMX_FB_HELPER, DRM_IMX_LDB, DRM_IMX_IPUV3).

This stopped with 2015-09.0. I even get a null-pointer exception:


Barebox: version 2015.09.0, DLoG 2015-09.1-9-g498cf3a
unable to handle NULL pointer dereference at address 0x00000008
pc : [<4fe1072a>]    lr : [<4fe10719>]
sp : 4ffffa18  ip : 4ffffa68  fp : 4ffffd80
r10: 3032678c  r9 : 00000000  r8 : 00000000
r7 : 30343904  r6 : 303438b8  r5 : 00000000  r4 : 303438b8
r3 : 00000000  r2 : 4fe31c78  r1 : 00000000  r0 : 00000006
Flags: nzcv  IRQs off  FIQs off  Mode SVC_32
[<4fe1072a>] (ipu_crtc_mode_set+0x2a/0x1cc) from [<4fe108f5>] (ipufb_enable_controller+0x29/0x44)
[<4fe108f5>] (ipufb_enable_controller+0x29/0x44) from [<4fe0e8e5>] (fb_enable_set+0x15/0x18)
[<4fe0e8e5>] (fb_enable_set+0x15/0x18) from [<4fe1bd6d>] (param_int_set+0x33/0x44)
[<4fe1bd6d>] (param_int_set+0x33/0x44) from [<4fe1bfab>] (dev_set_param+0x43/0x50)
[<4fe1bfab>] (dev_set_param+0x43/0x50) from [<4fe03257>] (setenv+0x37/0xac)
[<4fe03257>] (setenv+0x37/0xac) from [<4fe056cb>] (set_local_var.isra.3+0x37/0x4c)
[<4fe056cb>] (set_local_var.isra.3+0x37/0x4c) from [<4fe0622d>] (run_list_real+0x2ed/0x628)
[<4fe0622d>] (run_list_real+0x2ed/0x628) from [<4fe061c5>] (run_list_real+0x285/0x628)

[<4fe2d7cd>] (unwind_backtrace+0x1/0x74) from [<4fe00d65>] (panic+0x1d/0x2c)
[<4fe00d65>] (panic+0x1d/0x2c) from [<4fe2dca1>] (do_exception+0xd/0x10)
[<4fe2dca1>] (do_exception+0xd/0x10) from [<4fe2dd09>] (do_data_abort+0x21/0x2c)
[<4fe2dd09>] (do_data_abort+0x21/0x2c) from [<4fe2d9d4>] (do_abort_6+0x48/0x54)





I think (!) this is because of commit "video: ipuv3: Replace ipu_output with VPL".


My current device tree looks like this:

&ldb {
	status = "okay";

	lvds-channel at 0 {
		status = "okay";
		crtc = "ipu1-di0";
		fsl,data-mapping = "spwg";
		fsl,data-width = <18>;
		primary;

		display-timings {
			native-mode = <&timing0>;
			timing0: AM-800600K1TMQW-01H-B {
				// dot clock: 40 - 50 MHz
                                clock-frequency = <39701664>; // 72 Hz
				hactive = <800>;
				vactive = <600>;
				hsync-len = <3>;      // 1 - 40
				hback-porch = <46>;   // 46
				hfront-porch = <18>;  // 16 - 354
				vsync-len = <10>;     // 1 - 29
				vback-porch = <23>;   // 23
				vfront-porch = <3>;   // 1 - 77
				hsync-active = <1>;
			};
		};
	};
}


I experimented with barebox 2015.09.0 with several things, but so far haven't been successfull.



Any hint on how the device tree is now supposed to look like?