topic Re: i.MX6Q Dual channel LVDS output in kernel 3.10.53 / 3.14.52 in i.MX Processors

i.MX6Q Dual channel LVDS output in kernel 3.10.53 / 3.14.52

marcchapdelaine — Tue, 03 May 2016 15:56:39 GMT

I have a custom board with two 1920x1080 60Hz screens, one is using the parallel display and the other one is using the two LVDS channels outputs.

The board is working fine with the 3.10.17 kernel version. In the 3.10.53 and 3.14.52, I recreated the device tree (one for each kernel version). The parallel display is working properly. But the LVDS screen is working only at 1920x1080 25Hz.

In the "ldb" section of the device tree, I added the "split-mode" to use both LVDS outputs for a single display as documented inside the "Documentation/devicetree/bindings/video/fsl,ldb.txt" file. In the kernel logs, I have a line " ldb ldb.14: LVDS channel1 is not online" but if I define it I got a message telling me that lvds_channel1 is ignored in split-mode.

I'm providing traces and device tree sections for the LVDS video output:

Kernel version, kernel command line, output video mode and kernel trace
# uname -a Linux NeoTrans 3.14.52-135322-g5f6f0a5-dirty #3 SMP PREEMPT Mon May 2 15:37:10 EDT 2016 armv7l GNU/Linux # cat /proc/cmdline console=ttymxc3,115200 mtdparts=gpmi-nand:15m(kernel_a),1m(dtb_a),15m(kernel_b),1m(dtb_b),128k(startup_a),128k(startup_b),16m(ramdisk),-(free);spi32765.0:768k(uboot),64k(ubenv_a),64k(ubenv_b),-(free) rdinit=/linuxrc rootfstype=ext4 rw rootwait root=/dev/mmcblk2p3 video=mxcfb2:dev=ldb,1920x1080M@60,if=RGB24,bpp=24 video=mxcfb0:dev=lcd,1920x1080M@60,if=RGB24,bpp=24 ldb=spl0 consoleblank=0 fbmem=48M # cat /sys/class/graphics/fb2/fsl_disp_dev_property ldb # cat /sys/class/graphics/fb2/mode # cat /sys/class/graphics/fb2/modes U:1920x1080p-25 # # dmesg \| grep ldb Kernel command line: console=ttymxc3,115200 mtdparts=gpmi-nand:15m(kernel_a),1m(dtb_a),15m(kernel_b),1m(dtb_b),128k(startup_a),128k(startup_b),16m(ramdisk),-(free);spi32765.0:768k(uboot),64k(ubenv_a),64k(ubenv_b),-(free) rdinit=/linuxrc rootfstype=ext4 rw rootwait root=/dev/mmcblk2p3 video=mxcfb2:dev=ldb,1920x1080M@60,if=RGB24,bpp=24 video=mxcfb0:dev=lcd,1920x1080M@60,if=RGB24,bpp=24 ldb=spl0 consoleblank=0 fbmem=48M ldb ldb.14: split mode ldb ldb.14: split mode or dual mode, ignoring second output mxc_sdc_fb fb.19: registered mxc display driver ldb ldb ldb.14: LVDS channel1 is not online

Kernel version, kernel command line, output video mode and kernel trace

# uname -a

Linux NeoTrans 3.14.52-135322-g5f6f0a5-dirty #3 SMP PREEMPT Mon May 2 15:37:10 EDT 2016 armv7l GNU/Linux

# cat /proc/cmdline

console=ttymxc3,115200 mtdparts=gpmi-nand:15m(kernel_a),1m(dtb_a),15m(kernel_b),1m(dtb_b),128k(startup_a),128k(startup_b),16m(ramdisk),-(free);spi32765.0:768k(uboot),64k(ubenv_a),64k(ubenv_b),-(free) rdinit=/linuxrc rootfstype=ext4 rw rootwait root=/dev/mmcblk2p3 video=mxcfb2:dev=ldb,1920x1080M@60,if=RGB24,bpp=24 video=mxcfb0:dev=lcd,1920x1080M@60,if=RGB24,bpp=24 ldb=spl0 consoleblank=0 fbmem=48M

# cat /sys/class/graphics/fb2/fsl_disp_dev_property

ldb

# cat /sys/class/graphics/fb2/mode

# cat /sys/class/graphics/fb2/modes

U:1920x1080p-25

# dmesg | grep ldb

Kernel command line: console=ttymxc3,115200 mtdparts=gpmi-nand:15m(kernel_a),1m(dtb_a),15m(kernel_b),1m(dtb_b),128k(startup_a),128k(startup_b),16m(ramdisk),-(free);spi32765.0:768k(uboot),64k(ubenv_a),64k(ubenv_b),-(free) rdinit=/linuxrc rootfstype=ext4 rw rootwait root=/dev/mmcblk2p3 video=mxcfb2:dev=ldb,1920x1080M@60,if=RGB24,bpp=24 video=mxcfb0:dev=lcd,1920x1080M@60,if=RGB24,bpp=24 ldb=spl0 consoleblank=0 fbmem=48M

ldb ldb.14: split mode

ldb ldb.14: split mode or dual mode, ignoring second output

mxc_sdc_fb fb.19: registered mxc display driver ldb

ldb ldb.14: LVDS channel1 is not online

Device tree sections for kernel 3.14.52
/ { aliases { mxcfb0 = &mxcfb1; mxcfb1 = &mxcfb2; mxcfb2 = &mxcfb3; mxcfb3 = &mxcfb4; }; mxcfb1: fb@0 { compatible = "fsl,mxc_sdc_fb"; disp_dev = "ldb"; interface_pix_fmt = "RGB666"; default_bpp = <16>; int_clk = <0>; late_init = <0>; status = "disabled"; }; mxcfb2: fb@1 { compatible = "fsl,mxc_sdc_fb"; disp_dev = "hdmi"; interface_pix_fmt = "RGB24"; mode_str ="1920x1080M@60"; default_bpp = <24>; int_clk = <0>; late_init = <0>; status = "disabled"; }; mxcfb3: fb@2 { compatible = "fsl,mxc_sdc_fb"; disp_dev = "lcd"; interface_pix_fmt = "RGB565"; mode_str ="CLAA-WVGA"; default_bpp = <16>; int_clk = <0>; late_init = <0>; status = "disabled"; }; mxcfb4: fb@3 { compatible = "fsl,mxc_sdc_fb"; disp_dev = "ldb"; interface_pix_fmt = "RGB666"; default_bpp = <16>; int_clk = <0>; late_init = <0>; status = "disabled"; }; lcd@0 { compatible = "fsl,lcd"; ipu_id = <0>; disp_id = <0>; default_ifmt = "RGB24"; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_ipu1_1>; status = "okay"; }; }; &ldb { status = "okay"; split-mode; lvds-channel@0 { fsl,data-mapping = "spwg"; fsl,data-width = <24>; primary; status = "okay"; display-timings { native-mode = <&timing0>; timing0: hsd100pxn1 { clock-frequency = <65000000>; hactive = <1920>; vactive = <1080>; hback-porch = <220>; hfront-porch = <40>; vback-porch = <21>; vfront-porch = <7>; hsync-len = <60>; vsync-len = <10>; }; }; }; };

Device tree sections for kernel 3.14.52

/ {

aliases {

mxcfb0 = &mxcfb1;

mxcfb1 = &mxcfb2;

mxcfb2 = &mxcfb3;

mxcfb3 = &mxcfb4;

};

mxcfb1: fb@0 {

compatible = "fsl,mxc_sdc_fb";

disp_dev = "ldb";

interface_pix_fmt = "RGB666";

default_bpp = <16>;

int_clk = <0>;

late_init = <0>;

status = "disabled";

};

mxcfb2: fb@1 {

compatible = "fsl,mxc_sdc_fb";

disp_dev = "hdmi";

interface_pix_fmt = "RGB24";

mode_str ="1920x1080M@60";

default_bpp = <24>;

int_clk = <0>;

late_init = <0>;

status = "disabled";

};

mxcfb3: fb@2 {

compatible = "fsl,mxc_sdc_fb";

disp_dev = "lcd";

interface_pix_fmt = "RGB565";

mode_str ="CLAA-WVGA";

default_bpp = <16>;

int_clk = <0>;

late_init = <0>;

status = "disabled";

};

mxcfb4: fb@3 {

compatible = "fsl,mxc_sdc_fb";

disp_dev = "ldb";

interface_pix_fmt = "RGB666";

default_bpp = <16>;

int_clk = <0>;

late_init = <0>;

status = "disabled";

};

lcd@0 {

compatible = "fsl,lcd";

ipu_id = <0>;

disp_id = <0>;

default_ifmt = "RGB24";

pinctrl-names = "default";

pinctrl-0 = <&pinctrl_ipu1_1>;

status = "okay";

};

&ldb {

status = "okay";

split-mode;

lvds-channel@0 {

fsl,data-mapping = "spwg";

fsl,data-width = <24>;

primary;

status = "okay";

display-timings {

native-mode = <&timing0>;

timing0: hsd100pxn1 {

clock-frequency = <65000000>;

hactive = <1920>;

vactive = <1080>;

hback-porch = <220>;

hfront-porch = <40>;

vback-porch = <21>;

vfront-porch = <7>;

hsync-len = <60>;

vsync-len = <10>;

};

Re: i.MX6Q Dual channel LVDS output in kernel 3.10.53 / 3.14.52

igorpadykov — Wed, 04 May 2016 00:26:51 GMT

Hi Marc

could you try to work only with one lvds display, as operation with

two 1920x1080 60Hz screens is at i.MX6Q IPU perfromance limit:

from p.2729 i.MX6DQ Reference Manual (rev.3 7/2015)

The combined rate for the two ports is up to 240 MP/sec

http://cache.freescale.com/files/32bit/doc/ref_manual/IMX6DQRM.pdf

Best regards

igor

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Re: i.MX6Q Dual channel LVDS output in kernel 3.10.53 / 3.14.52

fulinux — Thu, 05 May 2016 08:59:57 GMT

Hi Marc,

have you solved you problem? can you help me to solve this thread problem: U:1920x1080p-35

thanks,

fulinux.

Re: i.MX6Q Dual channel LVDS output in kernel 3.10.53 / 3.14.52

marcchapdelaine — Thu, 05 May 2016 13:34:19 GMT

Hi Igor,

I tried with only the LVDS display (disabling the other screen on the LCD parallel port). I tried first on the command line (just removing the mxcfb1:LCD display, but it it still not working:

====

# dmesg | grep ldb

Kernel command line: console=ttymxc3,115200 mtdparts=gpmi-nand:15m(kernel_a),1m(dtb_a),15m(kernel_b),1m(dtb_b),128k(startup_a),128k(startup_b),16m(ramdisk),-(free);spi32765.0:768k(uboot),64k(ubenv_a),64k(ubenv_b),-(free) rdinit=/linuxrc rootfstype=ext4 rw rootwait root=/dev/mmcblk2p3 video=mxcfb0:dev=ldb,1920x1080M@60,if=RGB24,bpp=24 video=mxcfb1:off video=mxcfb2:off video=mxcfb3:off ldb=spl0 consoleblank=0 fbmem=48M

ldb ldb.14: split mode

ldb ldb.14: split mode or dual mode, ignoring second output

mxc_sdc_fb fb.17: registered mxc display driver ldb

# cd /sys/class/graphics/fb0/

# cat mode

U:1920x1080p-25

# cat fsl_disp_dev_property

ldb

# cd ..

# ls -l

total 0

lrwxrwxrwx 1 root root 0 May 5 13:07 fb0 -> ../../devices/soc0/fb.17/graphics/fb0

lrwxrwxrwx 1 root root 0 May 5 13:07 fb1 -> ../../devices/soc0/fb.17/graphics/fb1

lrwxrwxrwx 1 root root 0 May 5 13:07 fbcon -> ../../devices/virtual/graphics/fbcon

====

I tried also to comment the LCD output inside the device tree, but I have the same results.

====

lcd@0 {

compatible = "fsl,lcd";

ipu_id = <0>;

disp_id = <0>;

default_ifmt = "RGB24";

pinctrl-names = "default";

pinctrl-0 = <&pinctrl_ipu1_1>;

status = "okay";

};

====

Re: i.MX6Q Dual channel LVDS output in kernel 3.10.53 / 3.14.52

marcchapdelaine — Thu, 05 May 2016 13:59:35 GMT

Hi Fulinux,

I didn't have an answer yet. But your thread gave me some hints. I tried to change the clock speed from 65Mhz to 83Mhz and I have a 33Hz refresh instead of 25Hz. I'll ask the hardware team for complete specs of the display.

I will keep you in touch.

===

# cd /sys/class/graphics/

# ls

fb0 fb1 fbcon

# cd fb0/

# ls

bits_per_pixel cursor fsl_disp_dev_property modes power stride virtual_size

blank dev fsl_disp_property name rotate subsystem

console device mode pan state uevent

# cat mode

U:1920x1080p-33

Device Tree:

	lvds-channel@0 {
	fsl,data-mapping = "spwg";
	fsl,data-width = <24>;
	primary;
	status = "okay";

	display-timings {
	native-mode = <&timing0>;
	timing0: hsd100pxn1 {
	clock-frequency = <83000000>;
	hactive = <1920>;
	vactive = <1080>;
	hback-porch = <220>;
	hfront-porch = <40>;
	vback-porch = <21>;
	vfront-porch = <7>;
	hsync-len = <60>;
	vsync-len = <10>;
	};
	};
	};

Re: i.MX6Q Dual channel LVDS output in kernel 3.10.53 / 3.14.52

marcchapdelaine — Thu, 05 May 2016 18:16:16 GMT

Ok, I found the issue. It was the screen LVDS clock that was not correct. The screen i'm using has a 74.25Mhz LVDS clock, so changing the device tree to 148.5Mhz instead of 60Mhz fix the issue. I now have a 60Hz screen.

For reference, my ldb section of the device tree looks like this:

====

&ldb {

status = "okay";

split-mode;

lvds-channel@0 {

fsl,data-mapping = "spwg";

fsl,data-width = <24>;

primary;

status = "okay";

display-timings {

native-mode = <&timing0>;

timing0: hsd100pxn1 {

clock-frequency = <148500000>;

hactive = <1920>;

vactive = <1080>;

hback-porch = <220>;

hfront-porch = <40>;

vback-porch = <21>;

vfront-porch = <7>;

hsync-len = <60>;

vsync-len = <10>;

};

====

I will need to fix the porch values to fit my screen properly, but I now have the two 1920x1080 outputs at 60Hz.

Re: i.MX6Q Dual channel LVDS output in kernel 3.10.53 / 3.14.52

fulinux — Fri, 06 May 2016 02:51:57 GMT

Hi Chapdelaine,

Ok, As you said, it is ok with my lcd panel refresh, look like this:

# cat /sys/class/graphics/fb0/modes

U:1920x1080p-71

thanks for you professional answer.

ps. when i remove 'crtc = "ipu2-di0";', i can't input on my serial terminal, but It doesn't matter. have you ported viv-gpu-bin lib? is it runs ok?