i.MX ProcessorsのトピックRe: No display on HDMI Panel

No display on HDMI Panel

anilkumar — Tue, 23 Apr 2013 12:08:31 GMT

Hi All,

I am working on customer imx6q board and getting issue with HDMI.

I am getting HDMI panel detection kernel log but no display on HDMI panel.

I am using rootfs which i have created by busybox.

So my question, Is there any need of "mxc hdmi cec" lib or application in user space to enable HDMI in kernel ?

or HDMI display should start by default ?

Kernel Logs:---------------------------------

mxc_sdc_fb mxc_sdc_fb.0: register mxc display driver hdmi

mxc_hdmi mxc_hdmi: Detected HDMI controller 0x13:0xa:0xa0:0xc1

fbcvt: 1920x1080@60: CVT Name - 2.073M9

imx-ipuv3 imx-ipuv3.0: IPU DMFC DP HIGH RESOLUTION: 1(0,1), 5B(2~5), 5F(6,7)

mxc_sdc_fb mxc_sdc_fb.1: Can't get fb option for mxcfb1!

mxc_sdc_fb mxc_sdc_fb.2: Can't get fb option for mxcfb2!

mxc_sdc_fb mxc_sdc_fb.3: Can't get fb option for mxcfb3!

imx-sdma imx-sdma: loaded firmware 1.1

imx-sdma imx-sdma: initialized

mxc_hdmi mxc_hdmi: mxc_hdmi_set_mode: setting to default=1920x1080M@60 bpp=16

fbcvt: 1920x1080@60: CVT Name - 2.073M9

mxc_hdmi mxc_hdmi: mxc_hdmi_set_mode: New video mode

Serial: IMX driver

imx-uart.0: ttymxc0 at MMIO 0x2020000 (irq = 58) is a IMX

imx-uart.1: ttymxc1 at MMIO 0x21e8000 (irq = 59) is a IMX

console [ttymxc1] enabled, bootconsole disabled

loop: module loaded

Re: No display on HDMI Panel

ivankozic — Tue, 23 Apr 2013 12:41:09 GMT

Hi Anil,

Maybe you should post your boot config as well (while in u-boot, do 'printenv' and post it back) - there is a line there which states to which framebuffer did you map hdmi. For instance in our kernel all the secondary devices (other than fb0) are blanked by default and hdmi was mapped to fb2 and was blanked.

If it's a custom board you also might have a hardware fault with HDMI TMDS pairs.

Re: No display on HDMI Panel

anilkumar — Tue, 23 Apr 2013 12:53:54 GMT

I tried with below boot argument but getting No Signal message on HDMI Panel

setenv bootargs console=ttymxc1,115200 rw rootwait root=/dev/mmcblk0p1 init=/linurc video=mxcfb0:dev=ldb,LDB-XGA,if=RGB666 video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24 video=mxcfb1:off video=mxcfb2:off video=mxcfb3:off fbmem=20M vmalloc=400M

and

setenv bootargs console=ttymxc1,115200 rw rootwait root=/dev/mmcblk0p1 init=/linurc video=mxcfb0:dev=ldb,LDB-XGA,if=RGB24 video=mxcfb1:dev=hdmi,1920x1080M@60,if=RGB24

Re: No display on HDMI Panel

anilkumar — Tue, 23 Apr 2013 12:57:13 GMT

Now i tried with below boot argument also but getting No signal message

setenv bootargs console=ttymxc1,115200 rw rootwait root=/dev/mmcblk0p1 init=/linurc video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24 video=mxcfb1:off video=mxcfb2:off video=mxcfb3:off fbmem=20M vmalloc=400M

Re: No display on HDMI Panel

ivankozic — Tue, 23 Apr 2013 13:00:57 GMT

Ok, so the next thing is to see if hotplug works properly - when you boot it up completely try plugging/unplugging HDMI cable. You should get a message about hot-plug event from kernel.

Re: No display on HDMI Panel

anilkumar — Tue, 23 Apr 2013 13:08:04 GMT

Yes plugging/unplugging HDMI cable is working fine and getting EDID data also

Re: No display on HDMI Panel

ivankozic — Tue, 23 Apr 2013 13:11:51 GMT

Ok, EDID works over i2c, it has nothing to do with hi-speed stuff. Is this a custom board? Do you maybe have some level shifters or similar on TMDS lines?

Re: No display on HDMI Panel

anilkumar — Tue, 23 Apr 2013 13:23:56 GMT

yes it is custom board and using HDMI protection IC CM2020 as like sabre sd

Re: No display on HDMI Panel

ivankozic — Tue, 23 Apr 2013 13:53:59 GMT

Hmm... I see from the datasheet that TMDS lines are just clamped and go through - the level shifting is done only for control signals. Which means that this cannot be culprit.
If there's no more circuitry in path of TMDS lines, that means they are properly terminated at the other end. I would try the following. When system boots up, try executing 'echo 0 > /sys/class/graphics/fb0/blank'. Maybe it's blanked for some reason.

Re: No display on HDMI Panel

anilkumar — Tue, 23 Apr 2013 14:19:06 GMT

i tried already

'echo 0 > /sys/class/graphics/fb0/blank'

No result.

i am suspecting on cec driver in kernel because it need control by cec lib and cec application in user space to enable HDMI thing but i do not have cec lib and cec application in user space. Is it may be the issue ?

Re: No display on HDMI Panel

ivankozic — Tue, 23 Apr 2013 14:32:24 GMT

I don't think you need anything in user space for it, as my HDMI monitor fires up while kernel is still booting - right after the driver is loaded. And loading looks pretty much the same like yours.
I would also edit config files and kill all the unused framebuffers, as you've already disabled the output to them in u-boot. But this is unlikely to help. Maybe you have a HW fault - The TMDS lines are auto-sensing, so in general hot-plug means nothing for detection - TMDS lines should sense the proper termination impedance on their ends. Otherwise HDMI will not fire up even if there is a valid hotplug.

Re: No display on HDMI Panel

anilkumar — Tue, 23 Apr 2013 14:55:30 GMT

are you booting with android fs ?

Re: No display on HDMI Panel

ivankozic — Tue, 23 Apr 2013 14:59:18 GMT

No, just bare linux.

Re: No display on HDMI Panel

jimmychan — Thu, 02 May 2013 09:11:10 GMT

have you check the cec signal?

are you using different type of hdmi connector?

have you try it on other hdmi display?

Re: No display on HDMI Panel

LucasDonaiSfalc — Thu, 02 May 2013 22:26:45 GMT

Checked resolution hdmi u-boot?

My configuration u-boot is:

vid_dev0=hdmi,1280x960M@75,if=RGB24

Re: No display on HDMI Panel

karina_valencia — Fri, 17 May 2013 15:48:07 GMT

No update from customer

Re: No display on HDMI Panel

anilkumar — Sat, 18 May 2013 03:37:58 GMT

CEC signal is required ? I thing this signal is used to control multiple HDMI display.

and no need to implement but hw must be there for CEC

Re: No display on HDMI Panel

anilkumar — Sat, 18 May 2013 03:39:41 GMT

i passing it by boot arg as

video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24

Re: No display on HDMI Panel

anilkumar — Sat, 18 May 2013 04:02:37 GMT

I have some observation

1) HDMI display is working fine with sabre-sd and sabre-lite with my kernel but not on my board (My board HDMI hw is based on sabre-sd hw but missing 100om resistance and 0.1uF capacitor for SHELL1, SHELL2, SHELL3 and SHELL4 are there to give ground)

2) I disabled pad mux for CEC line and I2C and in this case sabre-sd board works for HDMI display fine also

a) Means now HDMI depends on HDMI TMDS data only.

3) I have checked in sabre-sd board there are 100om resistance and 0.1uF capacitor for SHELL1, SHELL2, SHELL3 and SHELL4 are there to give ground (not sure why this is for ) ?. this hw thing is not in my board. Is it may effect ?

4) TDMS_GND of CM2020 are internally connected with ground but these are externally ground also for sabre-sd baord. is it may effect ?

5) HDMI TMDS pins are dedicated to HDMI display only and there is no need of pin mux as these pins are by default configured ?

6) Is this possible HDMI display can work with HDMI TMDS data lines only , no CEC line and no I2C lines as it is working on sabre-sd case ? (Means i just changed the pin mux for CEC and I2C lines).

Sorry if any query is not clear.

Re: No display on HDMI Panel

karina_valencia — Mon, 20 May 2013 14:31:02 GMT

jimmychan can you continue the follow up on this case?