Posts: 11
Joined: Tue Jul 07, 2015 1:55 pm

13 seconds boot delay

Tue Jul 07, 2015 2:45 pm

I am just debugging a new board with the CM and have an annoying little problem I can't seem to solve.
When power is applied to the board, or RUN is allowed to go HIGH after being held at 0v, the CM seems to do nothing for 13 seconds. After that, I see 'Uncompressing Linux...' on the serial port and it boots up fine. The 13 seconds delay is also present if I issue a reboot command from Linux.

Now, if I plug the same CM into the CMIO board, it starts to boot almost instantly. Clearly, it's something about my board but I'm a bit stuck for ideas. I checked :
- rpi-buildroot and Raspian (with rpi-update today). Both behave the same.
- 2 different CM's and 2 different base boards.
- EMMC_DISABLE_N is always HIGH.

Our board has a LAN9512 and some I2C / SPI peripherals (currently not configured) and some GPIO inputs and outputs. It also has an HDMI to LVDS conversion but there is no connection to HDMI_CEC, HDMI_SCL and HDMI_SDA. We put hdmi_force_hotplug = 1 in config.txt and set the hdmi group / mode to allow for this. Is there anything else we should be doing ?

Thanks for any pointers as to where to look, or if anyone has seen this before...

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Re: 13 seconds boot delay

Wed Jul 08, 2015 4:30 am

do an update with rpi-update and see if that solves the issue. other than debug i am not sure what else could be a problem. -- Test board Eagle Cad Files.

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Raspberry Pi Engineer & Forum Moderator
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Re: 13 seconds boot delay

Wed Jul 08, 2015 5:39 am

Type "sudo vcdbg log msg", then look for warning messages and long gaps in the output. If it still isn't clear, upload the log somewhere and post a link here.

Posts: 11
Joined: Tue Jul 07, 2015 1:55 pm

Re: 13 seconds boot delay

Wed Jul 08, 2015 9:36 am

Thanks for your help. From the videocore logs it is obvious what is happening - it is trying to read the HDMI EDID, twice with 10 attempts each time. Each attempt is 500ms before it retries.
If I use :

Code: Select all


Code: Select all

in config.txt it prevents the second block of 10 attempts which halves the delay.
On the CMIO board (with no monitor plugged in), it does the same thing but the attempts are 1ms apart rather than 500ms so the delay is negligible. I suspect this is because the CMIO board has pull-ups on HDMI_SCL / HDMI_SDA but I'll have to solder these to the legs of the 200pin connector on out board to find out...Thanks again.

EDIT : In case anyone else runs in to this, a pull-up on HDMI_SDA fixed it.

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Re: 13 seconds boot delay

Fri Jun 01, 2018 11:29 am

I think this can be easily fixed in the firmware:
(My PCB is crowded enough as it is).
Check out our raspberry pi addons:

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