I have problem with Collibri T20 modules. Recently bought new modules do not start properly if they are quite cold (e.g. from cold room or fridge). On screen are displaying noises and flicker which seems to be hardware problem (in console mode letters are not displaying correctly - attached picture), and kernel booting is lock at always the same line:
[ 1.936023] tegra_nand: 1 NAND chip(s) found (vend=0x2c, dev=0xa3) (Micron NAND 1GiB 1,8V 8-bit)
[ 1.954986] tegra_nand: NVIDIA Tegra NAND controller @ base=0x70008000 irq=56.
[ 2.379333] 8 cmdlinepart partitions found on MTD device tegra_nand
After second or several power up when module is hot system starts normally and graphical noises does not apear.
This behaviour is observed during several tests on IRIS board and original Linux image from Toradex site.
Yes, this is a known issue which is believed to be fixed in more recent BSPs. Alternatively the fix may be back-ported aka cherry-picked into older BSPs.
This patch works fine with newer version of BSP (e.g. 2.6), but what about older v2.0 or v2.1? Using the same patch in kernel based on “colibri” branch doesn’t work. There is no difference between kernel with or without this patch.
This patch works fine with newer version of BSP (e.g. 2.6), but what about older v2.0 or v2.1?
As answered before you should be able to just cherry-pick resp. commit(s).
Using the same patch in kernel based on “colibri” branch doesn’t work. There is no difference between kernel with or without this patch.
I’m not sure what exactly you mean by ‘there is no difference between kernel with or without this patch’.
When I apply your patch (http://git.toradex.com/cgit/linux-toradex.git/commit/?h=tegra&id=943dd8a82f13c2e31a7f243bb15ae64edf45b7fa) to older kernel branch the behavior is the same like before applying patch - kernel doesn’t load and on screen is visible noises and flicker.
I have to admit that I never tried it with such old versions but would have expected it to fix it there as well. That said those older versions may exhibit various other issues long since fixed. I would therefore recommend using the latest stable kernel with just the following patch reverted in order to still be bootable on older BSPs.